Diplomarbeit
Building Shape Ontology Organising, Visualising and Presenting Building Shape with Digital Tools
ausgeführt zum Zwecke der Erlangung des akademischen Grades eines Diplom – Ingenieurs unter gemeinsamer Leitung von
o. Prof. DDI Wolfgang Winter Prof. DI Vinzenz Sedlak MPhil Institut für Architekturwissenschaften Institut für Architekturwissenschaften Tragwerksplanung und Ingenieurholzbau Tragwerksplanung und Ingenieurholzbau
eingereicht an der Technischen Universität Wien Fakultät für Architektur
von Philipp Jurewicz Matrikelnummer 9726081 Ruffinistr. 11a, 80637 München, Deutschland
Wien, den ______Building Shape Ontology Organising, Visualising and Presenting Building Shape with Digital Tools
Ontologie der Gebäudeform Organisation, Visualisierung und Darstellung von Gebäudeformen mit digitalen Mitteln Abstract (English) Choice of building shape is a central aspect of architectural design and often the starting point of interaction between architect and engineer designer. Existing sources to building shape were reviewed and the basic organisational layout identified. Connection points and overlapping sections between approaches were the starting point for a new meta classifica tion. A conceptual “building shape ontology“ describes building shape in a manner which is human readable and by using semantic mark up also “interpretable“ for knowledge-base soft ware applications. The shape ontology tries not only to sort building shape but also capture meaning and semantics of the field of interest. This is mainly an integration project and is based on established approaches. It only adds new content where the focus on the architec tural domain requires it. A foundation of a unified visualisation library with three dimension al models/renderings and two dimensional illustrations accompanies the text based ontology. A web application combines the organisation with the visualisation and serves as the present ation layer of this thesis.
Kurzzusammenfassung (Deutsch) Die Wahl der Gebäudeform ist ein zentraler Aspekt des Architekturentwurfes und dient oft als Ausgangspunkt in der Zusammenarbeit zwischen Architekt und Ingenieur. Bestehende Quellen zum Thema Gebäudeform wurden analysiert und ihre grundlegende Organisation identifiziert. Verbindungspunkte und überlappende Abschnitte der Ansätze begründen den Ausgangspunkt für eine neue Meta-Klassifikation. Eine konzeptionelle „Ontologie der Ge bäudeform“ beschreibt die Gebäudeform in einer Weise, die zum einen von Menschen lesbar und zum anderen mit technischen Markierungen auch für Wissensdatenbank-Software inter pretierbar ist. Die Ontologie versucht dabei nicht nur Gebäudeformen zu sortieren sondern auch ihre Bedeutung und Semantik zu erfassen. Dies ist ein Integrationsprojekt, welches auf bestehende Ansätzen aufbaut und neue Inhalte nur dort hinzufügt wo es der Fokus auf den Bereich Architektur nötig macht. Eine Grundlage für eine einheitliche Visualisierungsbiblio thek mit dreidimensionalen Modellen und Renderings als auch zweidimensionalen Illustra tionen begleitet die textbasierte Ontologie. Eine Internetanwendung kombiniert die Organisation mit der Visualisierung und dient als Darstellungsebene für die Ergebnisse dieser Diplomarbeit. Table of Contents
Introduction...... 6 Building Shape...... 9 1. Terminology...... 9 1.1. General Terms...... 9 1.2. Knowledge Base Terms...... 9 1.3. Typography...... 11 2. Background to this Project...... 12 2.1. IL Stuttgart Resources...... 12 2.2. LSRU Resources...... 13 2.2.1. Mnemonic code...... 14 2.2.2. Shapes Table in the SDA Database...... 14 2.3. Surface Geometry Resources...... 15 2.4. Polyhedron Resources...... 16 2.5. Further Mathematical Resources...... 17 3. Classification of Building Shape...... 18 3.1. Typology...... 18 3.2. Catalogue...... 19 3.3. Project...... 19 3.4. Shape Ontology...... 22 3.5. Interdependencies...... 22 4. Shape Typologies...... 24 4.1. General Typologies...... 25 4.1.1. Arrangement...... 25 4.1.2. Proportion...... 31 4.1.3. Surface...... 32 4.1.4. Truncation...... 35 4.2. Geometrical Typologies...... 37 4.2.1. Geometry 2D Angle...... 37 4.2.2. Geometry 2D Curve...... 38 4.2.3. Geometry 3D Solid...... 39 4.2.4. Geometry 3D Surface...... 45 4.2.5. Geometry 3D Spatial Curves...... 48 5. Shape Catalogues...... 49 5.1. SDA Building Shape Catalogue...... 49 5.2. Possible Further Catalogues...... 50 6. Projects Test Cases...... 53 7. Digital Data Concepts...... 58 7.1. Tables, Hierarchies and Data Graphs...... 58 7.2. Ontologies and the Semantic Web...... 59 7.3. How shape organisation benefits from data graphs...... 62 8. Digital Media...... 63 Summary...... 66 Conclusion...... 69 References...... 74 Appendix...... 77 1. Appendix A - Typologies...... 77 2. Appendix B - Catalogues...... 78 3. Appendix C - Web Application...... 79 4. Appendix D - Java Programming...... 84 5. Appendix E - Data Format OWL...... 86 6. Appendix F - Publication...... 87 Introduction Introduction Background and Intention Architecture is a profession of creating space. Most of the work aims to create buildings for our physical environment which can serve a specific need. One of the major effects is that buildings define and enclose space by their form. The “form” is one of the key terms in the discourse of architects and engineers and includes nearby all aspects of architecture, like aes thetics, function, morphology, structure, geometry etc. . Shape is the visible representation of an object and therefore only one aspect of form. While being “only one aspect”, it is the one with the greatest visual impact and this makes it of special interest considering the media so ciety we are living in. This work will deal with “building shape” and defines it as the outer visible representation of a building. Choice of building shape is a central aspect of architectural design and often the starting point of interaction between architect and engineer designer. In order to facilitate Figure 1: Screenshot of the ontology loaded into the Protégé choice, shape classifications provide useful and essential tools. editor Shape classification in architecture can also be used as a tool to assist investigation of the in teraction between shape, structure and material. The research of lightweight structures is of ten a search for optimisation and shape classification can help to recognise patterns, discover solutions and apply developed optimisation methods to related systems with similar shape characteristics. On the other hand of the spectrum architecture theory deals with shape as some theories manifest themselves in a distinct visual form language. The scale range for “building shape” can be assumed from large building complexes like air port terminals and train stations to objects which are big enough to enter them as a human, like tents or containers. This limitation should help to focus on a manageable domain and de velop a consistent classification. Researchers approached building shape from different perspectives and with the tools avail able at their time. While the basics of these classifications seem to work well within their sub domain there is still potential in how to satisfy all the actors involved in the built environ ment, so cross discipline communication can be simplified.
Figure 2: Shapes from the visualisation library
“Building Shape Ontology” by Philipp Jurewicz 6 Introduction
Aims There are three aims, which drive this thesis: Organisation - One aim is to provide a shape classification which can complement broader integration projects like [archistructura Online 2005] and the Structural Design Aid (SDA) [Sedlak 1996], where more aspects of buildings are investigated. Visualisation - Because shape is a very visual topic the illustration is of special importance. Like [Otto 1988] stated regarding to form description: photography and three dimensional models can carry tens of thousands data 'at a glance'. This thesis aims to find a consistent model for the visualisation of building shape. Presentation - The third aim is to define a presentation method that can communicate the classification and the visualisation to an academic audience. The Internet with its non-linear media characteristics is the targeted platform. Methods Figure 3: Screenshot of the web application showing the Mu nich Ice Skating Tent and related shape information The three aims dictate the methodology: In the review phase material about existing approaches was gathered and a draft mapping into a single data repository provided the “data workspace”. The underlying technology al lowed rich cross reference between the different resources for the identified connection points. This helped to recognise analogies and differences. The build up of the visualisation library in two and three dimensional computer graphics ap plications takes one in a very different “graphics workspace”. The information is mostly visu al and this allows to see shapes from a modelling point of view. Additional information and relationships which are hard to infer from literal data have been gathered. For the accessibility of a web application the utilised concept of learning from precedent ar chitecture requires to add building projects. The examples are classified with the above-men tioned data and the iterative process allows a fine tuning of the whole system. This also helps the classification to be more applicable in an architecture context. The usability beta testing of the web application results in more fine adjustment of the underlying data. The proposed classification/ontology is mainly an integration project and is based on estab lished approaches. It only adds new items where the focus on the architectural domain re quires them and where they couldn't be found in the review phase. E. g. the Arrangement typology in chapter 4.1.1 was partly developed for this thesis.
“Building Shape Ontology” by Philipp Jurewicz 7 Introduction
Chapter layout Chapter 1 “Terminology“ defines terms used throughout the text which is necessary because this paper involves two domains (architecture and computer science) with different language usage. Chapter 2 gives a “Background to this Project“ of reviewed existing approaches. Chapter 3 defines the “Classification of Building Shape“ introduced in this thesis and chapter 4 and 5 discuss this in more detail. Chapter 6 present a few test cases of real buildings and how they are classified according to the introduced ontology. Chapter 7 and 8 cover the tech nical topics about “Digital Data Concepts“ and “Digital Media”.
“Building Shape Ontology” by Philipp Jurewicz 8 Building Shape Building Shape 1. Terminology 1.1. General Terms The terms “typology” and “catalogue” are used specifically in this thesis to distinguish two main concepts. A (shape) typology is a well defined, consistent and closed set of data that is organised by hierarchical relations and graphs with the focus on one methodology. A cata logue is a collection of possible building shapes focusing on specific aspects like “researching lightweight structures”. Both terms will be defined in detail in chapter 3. “Project shape” is used to describe the shape of an already existing building or parts of it. ”Classification” is used according to its broad meaning 1 : the act or process of classifying 2 a : systematic arrangement in groups or cat egories according to established criteria; specifically : Taxonomy [Merriam-Webster Online 2005] ”Concept” is used according to its broad meaning and not as it is sometimes used in know ledge base system. 1 : something conceived in the mind : Thought, Notion 2 : an abstract or generic idea generalized from particular instances. Synonym see Idea [Merriam-Webster Online 2005] 1.2. Knowledge Base Terms Even though this is a thesis about building shape it uses terms from contemporary know ledge base / ontology research. This branch of computer science uses a special vocabulary to communicate concepts. There are some variations and I mainly follow the conventions used by the data format OWL [w3 consortium Online 2004] and the software application Protégé [stanford.edu Online 2005] as they are the tools used in the process of this thesis. For a more detailed discussion about the use of knowledge base concepts in this thesis please see chapter „7 Digital Data Concepts“
“Building Shape Ontology” by Philipp Jurewicz 9 1. Terminology
Ontology The term ontology is borrowed from philosophy where it's broadly defined as „a particular theory about the nature of being or the kinds of existent” [Merriam-Webster Online 2005] . Computer science community defines it slightly more narrow: A body of formally represented knowledge is based on a conceptualization: the ob jects, concepts, and other entities that are assumed to exist in some area of in terest and the relationships that hold among them (Genesereth & Nilsson, 1987) . A conceptualization is an abstract, simplified view of the world that we wish to repres ent for some purpose. Every knowledge base, knowledge-based system, or know ledge-level agent is committed to some conceptualization, explicitly or implicitly. An ontology is an explicit specification of a conceptualization.[Gruber 1993] Item The main audience of this paper is likely not to be familiar with knowledge base ter minology and the term „individual“ as it is used in ontologies can unnecessarily con fuse a reader coming from aa architecture background. I will substitute it with the word „item“ but use the same definition. Individuals [/items], represent objects in the domain that we are interested in, also known as the domain of discourse. [Horridge 2004] Property Properties are binary relations on individuals [/items]. A binary relation is a relation between two things. [Horridge 2004] In contrast to computer programmers, ontology users often use more human read able property names like „hasChildren“and „isChildOf“. This pattern is also used in the shape ontology. Because properties can define relations / links in a more fine grained way than the simple HTML Hyperlink, it is possible to weigh relations. For instance the so called „rdfs:isDefinedBy“ property is a very strong statement while the „rdfs:seeAlso“ property is a weak connection between two linked items. A variation are data properties, which do not link an item to an item but rather an item to a literal. The term literal describes common types of real data like strings, numbers and dates. For example a data property like „hasArchitect“ can have a string value of „Renzo Piano“, or a data property like “hasDiameter” can have a nu meric value of “100”.
“Building Shape Ontology” by Philipp Jurewicz 10 1. Terminology
Class (OWL) classes are interpreted as sets that contain individuals [/items]. They are described using formal (mathematical) descriptions that state precisely the requirements for membership of the class. [Horridge 2004] One of the most frequent relations between classes are hierarchies where one class is considered as a sub class of an other. It is important to keep in mind that in “graph data” structures a class can have more then one super class (see chapter 3). E. g. The class „Br – Brasilia - Parliament“ (describing the parliament building in Brasilia) could be the sub class of the classes „South America“, „Built by famous architects“ and „modernist project“. 1.3. Typography To avoid overuse of quotation marks classes and items are written in lower case italic. If the context makes it more appropriate classes and items are in quotation marks. Bold has no semantics attached and is used to emphasise words.
“Building Shape Ontology” by Philipp Jurewicz 11 2. Background to this Project
2. Background to this Project This chapter will give a brief overview of available approaches to shape classification, and discusses their potential, advantages and possible drawbacks with regard to this thesis. Apart from classification itself the reviewed research projects used information technologies (IT) available at their time. The following resource review takes this into account and reflects how a typical IT implementation with today's common systems might look like in each case. 2.1. IL Stuttgart Resources The Institute of Lightweight Structures, TU Stuttgart (IL) has a long tradition in the domain of form, structures, material and aesthetics. The institute published a series of five major publications (“IL21” – “IL25”) to document its Figure 4: Relations between elements and objects according approach to “Form – Force – Mass” which derived from 25 years of research. The scope of to IL Stuttgart their work focused on the interrelationship of form, force and mass, but shape stands at the beginning of their concept. The essentials in a few sentences: - Every object has a form. - Every object receives its form through a continuous process of creation - Every material object has the capability to transmit forces. It is “structure”. It can ans usually does experience loads and stresses. - The capability of a material object to transmit forces (known as Tra) is a function of the form, material and type of stress. - Material objects are then relatively light according to the principle of “Leichtbau”, when the ratio of mass to the capability to transmit force (i. e., to the Tra) is small. - [...] [Otto et al 1979]
The first publication in the series is a preview of the following four, to trigger academic dis cussion. The second publication focused solely on form/shape but should always be seen in context with the other. “IL 22 Form”[Otto 1988] is one key resources for this thesis. Because this source did not try a pure geometrical approach of shape classification it adds valuable aspects to the “building shape ontology” introduced later. It is also important to no tice that even though developed at a mixed engineering and architecture institute it tries to be Figure 5: Identification of elements within an arbitrary ob as general and broad in its view as possible. It deals with shapes from non-living nature, liv ject ing nature and man-made object in an abstract way.
“Building Shape Ontology” by Philipp Jurewicz 12 2. Background to this Project
The distinction against geometrical description of form is constituted as follow: The most accurate description of a form is that which causes even unknown (com pletely new) forms to be registered by the mind and familiar forms to be recog nised.[...] Much have been said and written about comprehension and recording of forms. Tra ditionally the geometrical method has been most popular. Forms are classified in a comparative manner using Euklidean bodies. Many objects found in inanimated nature, animated nature and engineering have very complicated forms. They can often be defined imperfectly using analogies with known geometric bodies such as cubes, spheres and cylinders. In spite of innumer able variations, almost all objects have a specific and often extremely characteristic form. They are instantly recognisable. [Otto 1988] There is no information technology mentioned in [Otto 1988] and the resulting classification method as described at the end of the publication represent a shape grammar. To a certain degree it could be mapped to a hierarchical data structure, but because it is a scaleless model Figure 6: Identification of one (D), two (DD) and three it's hard to point out what might be the root of such a hierarchy. (DDD) dimensional object proportions 2.2. LSRU Resources Related work and publications of the Lightweight Structures Research Unit, UNSW Sydney (LSRU) are more focused on the architectural implication of shape. Due to academic ex change the LSRU inherited many ideas introduced by IL Stuttgart and put them in an applied building project context. Cones, cylinders, prisms, polyhedra, etc. are entities that form “primary shape units“. The LSRU makes a further step and overcomes the limitation of strictly geometric main shapes by introducing domes and vaults as equal members of the classification. Connection between shape, structures and materials was one of the core research aims of the LSRU [Sedlak 1986], and this is reflected in the way it approached building shape. The inter action between shape and structure is crucial as described by [Loh 1990]. While a “building volume shape” vocabulary specialises on visible shape, a “structure shape” vocabulary con nects structures information tightly to shape information. While well known primitive shapes are the primary shape units of the building shape vocabu lary, further classification is applied by adding attribute groups. Based on the vocabulary by [Loh 1990] the LSRU approach evolves in two directions.
“Building Shape Ontology” by Philipp Jurewicz 13 2. Background to this Project
2.2.1. Mnemonic code These are rules how to connect abbreviation code into sequences so the shape of a building can be described. This mnemonic code is then applied in the project database of the LSRU. A selection of the projects together with generic information make up the Structural Design Figure 7: Examples project from SDA; ids: N06, I21, S579T Aid database (SDA). Following list shows example mnemonic code: • N 06 - ST. ANNES CHURCH SEAFORD Frankston (Fig. 7 left) Prism:8s:vert saddle top • I 21 - SOUTHCOAST HOUSE South Coast (Fig. 7 middle) Vault flat semi*2/b-to-b:assymm • S 579 T (SWIMMING POOL AND SPA Bad Dürrheim) (Fig. 7 right) Cone-saddle*5/2-way: 17s The mnemonic code has a grammar and is human readable after one learns the rules and knows the abbreviations which are documented in [Cox 1996]. Because building shapes can become complex the mnemonic code can take some liberty to describe significant parts in more detail. This can be seen parallel to a spoken language which is also based on a grammar but can express and emphasise details due to its context. It is very challenging to make such a grammar computer readable and software vendors like Microsoft are still struggling to support the well known English language in their word pro cessing applications. Because grammar and vocabulary of the LSRU's mnemonic code are very specialised it might be possible to develop a software “parser” with the same technolo gies used to parse spoken languages and computer programming languages. 2.2.2. Shapes Table in the SDA Database The second important product regarding to building shape is the SDA shapes database table. To understand it in its context one should take a brief look at the SDA as a whole. The key aim of the SDA is to provide architects, engineers, students and other de Figure 8: Examples from the SDA shapes table. Top row signers with an interactive tool during the conceptual design stage. This allows cones; below domes; below prisms; bottom row vaults design solutions to be established interactively, promotes valid decision making concerning structural system choice and facilitates assessing the impact of these choices on the building design. SDA provides a case study database resource for rapid information access; a cata logue of possibilities related to shape, structure, use, building envelope and materi
“Building Shape Ontology” by Philipp Jurewicz 14 2. Background to this Project
al as a design resource; and demonstrates the structural behaviour of selected case examples by computer simulation. It also has an intuitive graphical tool kit which examines the structural adequacy of a proposed building structure during the design process and provides guidance in choosing appropriate structure systems through statistical associations. [Sedlak 1997] The building shape table can be used as a depicted dictionary for the above mentioned mne monic code but does not cover all possibilities that are introduced there. The SDA was also used as a research tool for lightweight structures so a lot of shapes repres ent lightweight constructions like membranes. Building up on the research activities of the LSRU is a collection of pneumatic entries in the shape table. The shapes table must also be seen in its educational context, where it wants to introduce a wider variety of solutions to architecture students who are investigating for their design as signments. This is reflected in the polyhedron section of the table. The SDA uses File Maker [File Maker 2005] as its database. Early versions of File Maker em phasised on easy usability, graphical interfaces and integration of visual media which suited the SDA well. In its early implementation the SDA was not very relational, meaning that not many data rows had connections with data in other tables. This changed in the current ver sion of the SDA database but content work to edit all this connection is still to be done. The shapes table builds up on [Loh 1990] but it would be very inefficient to map all different permutations of attributes into entries, so the table is an editors selection of important shapes regarding to other SDA database tables and research project of the LSRU. 2.3. Surface Geometry Resources Description of building shape by specifying the surface is very common in architecture fields like shell and membrane structures. The applied research field of concrete shells is successful in utilising surface geometry for construction of buildings. This has already its foundation in early concrete buildings. The research by [Joedicke 1962] gives a good overview. While [Joedicke 1962] sees surface geometry from an architectural and engineering point of view it can be complemented by the work of [Gheorghiu 1978]. This book „Geometry of Structural Forms“ was done from a technical drawing point of view before CAD was widely available and it covers many shapes that are important for architecture and civil engineering. Because the authors had a mathematical background they classified similar shapes to [Joedicke 1962] in a “geometrical way”. A further resources which tries to bridge maths and
“Building Shape Ontology” by Philipp Jurewicz 15 2. Background to this Project
architecture is [Martins 1996]. A pure mathematical approach can be found at “MathWorld” [wolfram.com Online 2005] (http://mathworld.wolfram.com/topics/Surfaces.html) which takes advantage of the multi media capabilities of the Internet. 2.4. Polyhedron Resources Polyhedral solids have a rich history in the field of mathematics, as they originate from Greek ancient science. Regular polyhedra follow very strict mathematical rules and have a unique visual language. They are well researched and their potential for architecture is well docu mented. The key resources used for the building shape ontology are „Order in Space“ by [Critchlow Figure 9: 1: point; 2: line; 3: plane; 4: solid 1969], „Geometrie der Knoten-Stab-Tragwerke“ [Emde 1977] and Internet resources like [wolfram.com Online 2005] [Critchlow 1969] starts with a description of some basic well known axioms of geometry and the polyhedra evolve as logical consequences which ease access to the concept (see Fig. 9)The author often uses spheres as an envelope for polyhedra to describe spatial configura tions and internal building blocks. Faces elements that make up polyhedra, are investigated in more details. Morphing and deformation of standard solids is also discussed. The chapter about “space filling surface pattern” lays down the foundation to understand polyhedral close packing, which is illustrated for spatial configurations in the appendix of the book. [Emde 1977] is compiled as lecture material from the “Strukturforschungszentrum e.V. Figure 10: Platonic solids: tetrahedron, [cube skipped], oc Würzburg” association which was supported by Mero. This company pioneered mass pro tahedron, dodecahedron and icosahedron duction of space frames and polyhedra are the theoretical background. The author provides a good visualisation how different Platonic, Archimedean and Catalan solids are related to each other. Polyhedra and close packing are also analysed from a building perspective which makes it a valuable resource for this thesis. Especially polyhedra can benefit from multimedia capabilities of Internet resources like “MathWorld” (http://mathworld.wolfram.com/PlatonicSolid.html ) [wolfram.com Online 2005] and [maths.org Online 2005] that use interactive 3D visualisation. It makes it easier to understand these kind of spatial objects than with a static visualisation on paper and images. Small educational shareware tools like “Poly” [peda.com Online 2005] are also noteworthy.
“Building Shape Ontology” by Philipp Jurewicz 16 2. Background to this Project
2.5. Further Mathematical Resources Though already mentioned above in specific sections one can state that the Internet became a major resource especially for mathematics. This thesis make extensive use of two resources. “MathWorld” [wolfram.com Online 2005] (http://mathworld.wolfram.com/) is a well estab lished Internet resource which is backed by software vendor Wolfram Research. “Connecting Mathematics” [maths.org Online 2005] (http://thesaurus.maths.org) is backed by Cambridge University and due to its internationalisation it gained a lot of peer review. Be side of its content value it has also an implementation value because it uses a data organisa tion for its thesaurus with typed links like “broader, narrower, references, referenced, ...” which can be seen as a predecessor of a “Simple Knowledge Organization System” (SKOS) [w3 consortium Online 2004]. SKOS is related to the “Web Ontology Language” (OWL) [w3 consortium Online 2004] which plays an important role in this thesis.
“Building Shape Ontology” by Philipp Jurewicz 17 3. Classification of Building Shape
3. Classification of Building Shape The use of building shape extends across several fields: Architecture theory, visual design, so cial arts, building technology, engineering and geodesy. They have different points of view toward the shape of a building and developed classifications that serve their particular needs within their domain. But it is difficult to satisfy all people involved with one approach. Contrasting points of view can be illustrated by a soap bubble that can be seen from a de scriptive aesthetics as well as from a very strict geometrical perspective (see Fig. 11). The domain of building shapes can be separated into three main parts: typologies, catalogues and projects. 3.1. Typology
Figure 11: Soap bubble A (shape) typology is a well defined, consistent and closed set of data that is organ ised by hierarchical relations and data graphs with the focus on one methodology. For instance a “solid body geometry” typology assumes that all its members are solid three dimensional shapes and therefore have volume. The taxonomy is based on well known solid shapes like cone, sphere, prism, pyramid, etc. and sub branches consider parameter like regu larity (general prism, right prism, regular prism (see also Fig. 59) A typology should be as exhaustive as possible in its domain, but the “open world assump tion” still applies. The open world assumption means that we cannot assume something doesn’t exist until it is explicitly stated that it does not exist. In other words, because something hasn’t been stated to be true, it cannot be assumed to be false — it is assumed that ‘the knowledge just hasn’t been added to the knowledge base’. [Horridge 2004] While this assumptions appears trivial at the beginning it is essential to keep it in mind when one wants to develop the shape ontology into a conceptual model that can be used for com Figure 12: Solid, surface and wireframe representation of puterised analysis. the same shape Typologies often describe the same visible shape in very different ways (E. g. solid geometry vs. surface geometry; see Fig. 12) with their own set of axioms. It is legitimate to have more than one definition of a shape in the ontology as long as the particular definitions are consist ent within their own typologies.
“Building Shape Ontology” by Philipp Jurewicz 18 3. Classification of Building Shape
Typology items are distinct single entities. They are units and can not be arranged into ag gregates and composites (see catalogue items and project items defined below). If there is a situation where aggregates appear the classification should be reviewed and reconsidered. Typology items can refer to other typology items with properties like „see also“, „is defined by“, „has typology“ etc. Each carefully set property / reference enriches the whole shape on tology and makes it more descriptive. 3.2. Catalogue A catalogue is a collection of possible idealised building shapes focusing on specific aspects. Catalogues serve a purpose. The internal classes, items and properties of catalogues have a layout for a specific task like researching timber construction, mem brane structures or social aspects of buildings. Catalogues can be assembled with a specific set of projects in mind. This is legitimate be cause catalogues are not claiming to be complete and exhaustive collections, they are applica tion driven. Catalogue items can be assembled/split up into components, units, aggregates and compos Figure 13: Egyptian pyramids in Gizeh; Five units and ag ites in the same way as project items. One should try to avoid the use of composites as cata gregates form a composite logue items and be as simple as possible. But implementation of catalogues shows that sometime this is not avoidable. Catalogue items can refer to each other with weak „see also“ properties. It must be left open if it makes sense that catalogues can make strong „is defined by“ statements in between them. This decision must be postponed until a second major catalogue is introduced. 3.3. Project Architecturally interesting buildings are the domain of my meta classification and it is import ant to incorporate a base of proof-of-concepts projects to evaluate the shape ontology. Even though buildings have many aspects like material, structure, application, architecture theory, etc. for a building shape ontology the visual outer shape is the most important one. Structural features are often driving the shape of a building and represent a separate aspect. Interaction between structure and shape is not the topic of this thesis. There are a lot of publications about this connection. Even though this thesis is written in a team environment Figure 14: sand stone bricks form the elements the pyramid where most members are active in structural research and engineering, I hope that focusing unit
“Building Shape Ontology” by Philipp Jurewicz 19 3. Classification of Building Shape
solely on shape makes the findings more objective. In further research the shape ontology should be incorporated back into a more general architecture knowledge base. The shape ontology is currently scale neutral. This can be seen as a feature to find relations between projects bridging the very dominant scale barrier in the head of building profession als. Still scale for building shapes is not infinite and has a common range from approximately one meter up to a few hundred meters. If a later stage shows a significant amount of unsatis fied inferred results a consistent concept of scale should be introduced. On the other hand having the ontology scale less, keeps a possibility open to use it as a starting point for a gen eral architectural shape ontology. One usage pattern from LSRU work followed in this thesis is the split up of a building into smaller parts so they can be looked at separately. Figure 15: Egyptian step pyramid in Saqqara; Five units The IL introduced this in its very generic way stating that „objects“ can be made out of form a aggregate „components“, that are roughly the same scale, and all of this can be made up of „elements“ which are of a significant smaller scale. To keep it infinite each object itself can be an element of a bigger object and so forth. The term element can be broadly defined as 2 : a constituent part: as a plural : the simplest principles of a subject of study : Rudiments b (1) : a part of a geometric magnitude
“Building Shape Ontology” by Philipp Jurewicz 20 3. Classification of Building Shape
An object that is composed of a number of elements is termed a UNIT OBJECT. Each one of its elements may be one-, two- or three-dimensional. An object that is composed of more than one unit object is called an AGGREGATE OBJECT. Each one of its units may be one-, two- or three-dimensional. An object that is an assembly of aggregate objects is termed COMPOSITE OBJECT. These aggregates may be one-, two- or three-dimensional.[Sedlak 2003 Online] For instance an Egyptian step pyramid could be an aggregate shape made up by tapered slab units, which are made up of spatial sand stone cuboid elements. Again this relation is of the “same kind”: we deal with solids throughout the zooming (see Fig. 15). Further the term “component” broadly defined as „a constituent part : Ingredient” [Merri am-Webster Online 2005] will be used to describe parts of shapes which are “not of the same kind”. For instance a cube is made of six surfaces. While the cube itself is a solid the sides are surfaces. In this case the square surface is a component of the solid cube. A second example can see the edges as components of a pyramid unit (see Fig. 16). In the same way a valley or a high point in a surface is not an element but rather a compon ent. This usage differs slightly from [Otto 1988] where term “component” is roughly the same as the split up of unit, aggregate and composite in [Sedlak 2003 Online]. Essentially the “component” level is already introduced in the LSRU's mnemonic code for shapes. By using sequences like „Prism rect raked: concave top“ (SDA Project A528 VI CENZIA OFFICES Montecchio) the word „top“ is describing a surface component of a solid unit. To keep the computer data layout consistent and manageable the term „project item/shape“ will be used for unit, aggregate and composite of building projects. Especially for properties Figure 17: The parliament building in Brasilia can be seen which connect buildings with catalogue items and typology items. F. i. as depicted in Figure as an composite containing the four parts base, dome, 17 the whole building would be a composite containing the base, dome and bowl as units high rise and bowl. The high rise is an aggregate of to and the high rise as an aggregate. The high rise itself contains two units of cuboids. The four cuboid itself. project items can be investigated separately making it possible to connect the dome part with other dome projects around the world. Because all parts are sub classes of the composite class „parliament building Brasilia“ their location context is preserved. Whole building project have no logical super class as a shapes. To make the data manageable the ontology uses four super classes which only indicate the detail level of the gathered in formation: analysis level 0, analysis level 1, analysis level 2 and analysis level 3. A more user friendly taxonomy to access project shapes by location, climate zone and applic
“Building Shape Ontology” by Philipp Jurewicz 21 3. Classification of Building Shape
ation is implemented outside of the “shape branch” as a sibling branch. It is utilised by the web application. 3.4. Shape Ontology Based on the three major parts and the definition of the term ontology in computer science we can now define the shape ontology: The shape ontology is the specification how ty pology shapes, catalogue shapes and project shapes are connected and what rules they must be committed to, to work well with each other. It is important to understand the difference between the approach introduced in this thesis as the “building shape ontology” and the approach by [Loh 1990]. The LSRU publication de scribes primary „building volume shape“ and „structure shape“. Building volume shape is more related to my research and is defined as „The overall silhouette enclosing the space, by surfaces and edges“ [Loh 1990]. The building shape ontology is broader by trying to answer the question „which shape char acteristics of a particular building are so significant that it is possible to distinguish or relate the building with other building projects?“ This broader view allows an integration of the “building volume shape” approach, which is also the foundation of the SDA building shape database table, as a catalogue within the whole framework as described in chapter 5.1 . 3.5. Interdependencies In ontologies connections, links and relations are represented by properties, as described in chapter “1.2 Knowledge Base Terms“. The property concept of the shape ontology makes it different from a thesaurus, a vocabu lary or a plain typology as described technically in chapter “7 Digital Data Concepts“. The relevance of connections is subjective to the editor, and they should be established with care. One benefit of using an ontology is that so called „reasoner“ software modules can in fer logical connections so the result is enriched with additional information. This can be used as a valuable tool to check for consistency within content. It is helpful to establish some weighting so the software does not infer to many unpredictable and unfounded relations especially between project shapes. The weighting pattern is ex
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pressed in properties like „has primary something“ and „has secondary something“. At the current stage two levels seem to be sufficient but more levels could be introduced in future versions if necessary . The weighting does not only serves the needs of the software but also helps to understand projects for a human. Projects and Catalogues Shapes of building can become fairly complex and it is necessary to distinguish between primary and secondary properties (“has primary catalogue item”, “has sec ondary catalogue item”). A project item can be connected to one or more catalogue items in one or more catalogues. Projects and Typologies There is a distinction between primary (“has primary typology item”) and secondary (“has secondary typology item”) properties. At the current stage of implementation two properties “has plan” and “has section” have been added. Connecting example projects showed that plan and section are sig nificant concepts with a special meaning in architecture and therefore distinguishable links for plan and section into the geometry 2D typology are good to omit confu sion. The need for a “ground plan catalogue” is eminent and should be implemented in future research. Catalogues and Typologies Catalogue items can refer to typology items in a more precise way than project items. To allow this detailed connection the „has typology“ property has sub properties which are mirroring the available main shape typologies (e.g. „has arrangement“, „has geometry 3D“, „has truncation“ etc.)
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4. Shape Typologies The current implementation of the shape ontology incorporates six typologies, namely ar rangement, geometry 2D, geometry 3D, proportion, surface and truncation. The geometry 3D typology consist of two major geometry 3D solid, geometry 3D surface and one minor geometry 3D spatial curve sub branches. The heritage of a typology is an important information and two main groups can be identi fied: geometrical typologies and so called “general typologies”. General typologies describe shape in a more indirect way and are less constrained by a binary model where there is only a strict yes or no. One could state that general typologies can also be called „architectural typologies”, because they are utilising a language which conforms to a building professional. But the surface and the proportion typologies which both derive from [Otto 1988] try to describe an object regardless if it is found in living-nature, non-living- nature or is man-made. This included approach makes a naming as „general typologies“ more appropriate. By having shape typologies from both ends of the spectrum incorporated into the shape on tology, it should be possible to classify projects of a wide variety. Typology items are more/finer defined the deeper they are situated in a typology hierarchy. E. g a square is a special case of a rectangle, which by itself is a special case of a rhombus or a trapezoid and so on. Figure 20 shows that this can lead to deep hierarchies. Maybe unhandy on a first look they have the advantage that a computer can later infer that building projects with a rhombus plan have more similarities with building projects that have a square plan than projects with a circle plan. This is one of the basic decision for my research project. A flipped layout where more com monly known but stricter defined items are at a higher level (like square), is ridged when one Figure 18: Typology path from a general quadrangle up to has to describe a project that differs slightly from well known shapes. square A further advantage is that catalogue items and project items can be tagged even when an user is uncertain about a topic. E. g. in the wide variety of geodesic polyhedra it is now pos sible to describe a project shape as „some kind of geodesic polyhedron“. Other project shapes, maybe better analysed, can be referred as „frequency 6 icosahedron“. They are still related to the first project shape because their class is a subclass of the general geodesic polyhedron class. Subclasses should always follow the same pattern within their main branch and not mix as
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pects. E. g. the 90 degree angle which is used in a significant proportion of buildings can be the driving aspect for the definition of subclasses. A “snapping“ of a present angle in a more general super class to 90 degree in the subclass is a pattern which can be often identified in the shape ontology (E. g. with prisms or the above mentioned square). (see Fig.18, 19 and 20) All typology classes have at least a default item. If an user who adds projects to the ontology is not certain about further details of a project he can refer to this default item. Sibling items can be added when necessary. They represent variations within the characteristic of the class. Where variations are repetitive and well structured they are regrouped into sub classes with their own default items. Figure 19: general pyramid, right pyramid, regular pyramid and tetrahedron When a branch has subclasses and sibling items it tries to be consistent so the reason for sub classes should always be the same. Often sibling items have a parallel pattern, and it's the ed itor decision that, at the moment, one characteristic is more important and should be the foundation of a branching. To a certain extend this data classification is still flexible. The data concept underlying the shape ontology is based on graphs and therefore classes can be mem bers of more than one hierarchy. The basic idea is that a visible hierarchy is only one repres entation, or view, of the connected data graph and therefore one can define other views of the same data that can coexist next to each other. For a detailed discussion of this topic please see chapter 7 “Digital Data Concepts“. An example can be found in the geometry 3D Figure 20: general prism, right prism, regular prism and solid main branch. Where the geometry 3D type branch offers a different order of the commonly cube/hexahedron known cone, cylinder, ellipsoid, prism, pyramid, etc.. A second example is the main branching in the geometry 3D surface typology. The following sections will discuss the organisational layout of all included typologies. Ap pendix A provides an exhaustive list of all considered items. 4.1. General Typologies 4.1.1. Arrangement The most relevant definition of the term arrangement in an architectural context is „something made by arranging parts or things together“ [Merriam-Webster Online 2005] The arrangement typology derives from an architectural background. Though it uses terms which also have a geometrical meaning like “axis” and “orientation” it orders them in a way that suits more the needs of buildings then strict mathematical expressions.
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The typology is partly based on the definitions by [Loh 1990] (e. g. symmetry). Further re sources like “Order in Space” [Critchlow 1969] are used to include more information in the spacing branch. The axis branch follows [Loh 1990] but was rearranged for this research pro ject. For project items and catalogue items, arrangement can be used to describe relations of the same order like “unit to unit” and “aggregate to aggregate” and also for hierarchical order like “unit to aggregate” and “aggregate to composite”. The first level of arrangement is abstract and lists main branches that cover topics like axis, packing, orientation, symmetry, etc. Axis The term axis has, beside of other, a mathematical and an architectural meaning. A general definition is: 1 a : a straight line about which a body or a geometric figure rotates or may be supposed to rotate b : a straight line with respect to which a body or figure is symmetrical [...] 6 a : an implied line in painting or sculpture through a composition to which elements in the composition are referred b : a line actually drawn and used as the basis of measure ments in an architectural or other working drawing [Merriam-Webster Online 2005] Figure 21: A parabola loca For the arrangement typology the later definition is utilised. This way axes are not tion curve with one virtual axis bound to straight lines but rather represent “important curves” within shapes which can also be curved/smooth. The approach allows to integrate the “non-straight im portant curves” in a consistent way together with straight lines. A typical curved member is a parabola, which incorporates one symmetrical straight axis but is curved by itself (see Fig. 21). The associated figures distinguish between straight virtual lines (point dotted lines) and location curves that represent the points where an object would be placed. Please notice that the axis branch does not define symmetry, this happens in a separate branch introduced later. The main layout organisation for subclasses at this level is the number of axes. It is important to understand, that a parallel offset of an axis does not qualify as a second Figure 22: Peripheral and radial axis arrangement axis. (see Fig.25) Numbers of one to six are present as distinct subclasses. The class multiple axes covers cases where even more axes can be identified though this is rare in the classification of building shapes. Furthermore the classes no axis and no order cover special cases. No axis describe cases where no axis can be recognised but still
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some kind of order can be visually identified. No order describes the case where no order at all can be identified. The following level is a distinction between radial and peripheral arrangement. Radial arrangement emphasises on a common centre where the intersection is part of the objects that are arranged. A peripheral arrangement can also have a centre but in gen eral objects surround this logical centre which remains as a void (see Fig. 22). Espe cially after applying some truncations/trims the decision if a project shape is rather a radial or a peripheral arrangement can be ambiguous. The right interpretation can come from the architectural theory background of the building. Peripheral arrange ment is also known as circumferential arrangement. Figure 23: snapping of an arbitrary angle to a perpendicu lar angle The next subclass level is a “snapping” from an arbitrary angle to a 90 degree angle. (see Fig. 23) Further characteristics are not represented in subclasses but rather in sibling items with different data properties. One characteristic is the trimming of certain parts of the location curve to emphasise a break in continuity. (see Fig. 24) The term trim was chosen in favour of truncate, as it is found more often in CAD and graphics software when it comes to curves and surfaces. The term truncate implies volume and mass which are not present in axes. A further characteristic is the duplication of an existing location curve by parallel off set. The result can consist of multiple parallel location curves but the number of axes remains unchanged. (see Fig. 25)
Figure 24: Trimming of one axis
Figure 25: parallel offset
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Cardinality The term cardinality is defined as “the number of elements in a given mathematical set” [Merriam-Webster Online 2005]. There are often significant numbers in pro jects, for instance the number of units, high points, axes etc. . This branch with no sub classes gives simple access to a unified way to refer to cardinality and numbers. Numbers from one to twelve can be referred directly. The more general items many and none complement the set. While class names in an ontology are strings and tailored to be human readable, the actual computer-interpretable number is stored in the integer data property “is car dinality”. Orientation The major classes are horizontal and vertical with the inclined class covering the rest. Though there is a vertical inverted class there is no „horizontal inverted“ class because one can assume that it is possible to „walk“ around a horizontally oriented object, so Figure 26: Linear Spacing: gap, packing, overlap and blob- front and back are exchangeable. like-overlap Spacing The content in the spacing branch describes how objects treat the interspace between each other. There are three main classes: • Gap: leaving a visible gap to a neighbour object (see Fig. 26).
Figure 27: partial linear packing, space filling linear packing, • Packing: having contact exact at the boundary surface with a neighbour ob partial planar packing and space filling planar packing ject. (see Fig. 26, 27 and 29) • Overlap: objects overlap and the resulting enclosed volume is different to the sum of the separate volumes. (see Fig. 26). Blob-like-overlap and penetrate- overlap are implemented as sibling items.(see Fig. 26 and28). The next sub class level is the characteristic of the considered dimensions. The ar rangement can be linear, planar or spatial (see Fig. 27) followed by regularity (see Fig. 29) Figure 28: blob-like-overlap, linear blob-like-overlap, penet rate-overlap and linear penetrate-overlap The packing characteristic is of special interest as it can be utilised to create regular ar rangements of shapes. This thesis follows the concept described by [Critchlow 1969]. Packing combined with spatial parameter (one, two and three dimensional)
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defines the following cases: • Linear packing (one dimensional) is a sequence of objects arranged on an axis that are so close to each other that their boundary surfaces have contact. When all neighbouring contact surfaces match each other we can speak of space filling linear packing, otherwise we have partial linear packing • Planar packing; (two dimensional) When all neighbouring contact surfaces match each other we can speak of space filling planar packing, otherwise we have partial planar packing. Regular polyhedral combination are a special group inside the space filling planar packing class. The regular triangular, cubic Figure 29: none-regular planar gap, regular planar gap, and hexagonal prisms are the only self packing shapes. Four dual and three none-regular planar packing and regular planar packing triple combinations can also be achieved with regular prisms. Beside of the regular prisms a wide variety of other shapes can be used for space filling surface pattern (see also “Tessellation” chapter 4.2.1) • Spatial packing; (three dimensional) When all neighbouring contact surfaces match each other we can speak of space filling spatial packing, otherwise we have partial spatial packing. Again regular polyhedra form some special cases and a stack of space filling planar packing can also be considered a spatial pack ing. Beside of the regular polyhedra cases there are numerous non-regular shapes that can be used for spatial packing. Space filling spatial packing is some times referred to as “close packing”. • Polyhedral close packing is a different organisation of the polyhedral special cases mentioned above. The organisation follows [Critchlow 1969] and defines self, dual, triple and multi sub classes. Symmetry A common definition of the term symmetry is: 1 : balanced proportions; also : beauty of form arising from balanced proportions 2 : the property of being symmetrical; especially : corres pondence in size, shape, and relative position of parts on opposite sides of a dividing line or median plane or about a center or axis. [Merriam- Webster Online 2005] This thesis is following [Loh 1990] who describes four principal types of symmetry: bi lateral, translatory, dilatation and rotational (see Fig. 30):
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Bilateral - Bilateral symmetry is a balanced arrangement of equivalent elements about a common axis. That is one plane divides the whole ar rangement into two identical halves. Translatory - Translatory symmetry involves a repetition of a single unit in one direction. Simplistic translatory symmetry occurs when the pattern is invariant when translated along a line, (similar to linear arrangements). A more complex translations involves variable distances of translation. Functional systems such as quadratics and logarithms are examples of devices to facilitate variable translation. Dilatation - Webster's dictionary defines dilatation as: “di·la·ta·tion n 3: the action of being expanded: the state of being expanded.” Dilatation is a derivative of translatory symmetry. In dilatation the unit is enlarged or reduced as the unit is translated. When reduction or enlargement occurs the repeating pattern is similar but not congruent. Rotational - Rotational symmetry is another derivative of translatory symmetry. Rotational symmetry involves a translation along a circle or about a cylinder (or sphere).[Loh 1990] Bilateral symmetry is also known as “reflective” or “mirror” symmetry.
Figure 30: Bilateral (top right), transitional (top left), rotational (lower right) and dilational symmetry (lower left).
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4.1.2. Proportion The concept of proportions is important in the architectural context. This thesis is following the usage introduced by [Otto 1988] and [Sedlak 1986] The form of an object is characterised above all by it's proportions. Proportions are the relationship between the dimensions (width/length/height) Every object has a mass, a volume and a surface. Every object has finite dimensions in all three di mensions. It is always three-dimensional. One and two-dimensional objects do, strictly speaking, not exist: if they were only linear or two-dimensional they would have no volume and therefore no mass. In the present publication we do,however, apply the terms „one-dimensional“ and Figure 31: Proportions; three, „two-dimensional“ to objects. This usage of terms is based on the characteristic and two and one dimensional formal properties of the objects.[Otto 1988] “One-dimensional”objects are those in which one dimension is considerably larger than the others. „Two-dimensional“ objects are objects in which two dimensions are considerably larger than the third.[Otto 1988]
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4.1.3. Surface A common definition of the term surface is: 1 : the exterior or upper boundary of an object or body; 2 : a plane or curved two- dimensional locus of points (as the boundary of a three-dimensional region) [Merri am-Webster Online 2005] The key source for the surface typology is [Otto 1988]. While Otto states that the “above all” characteristic is the proportion, he closes his chapter about proportion with the statement: Three-dimensional objects are essentially defined by the shape of their surface. [...] The number, size and shape of the existing surfaces, points, edges and corners de termine the form of three-dimensional objects to a particular large extent. [Otto Figure 32: synclastic (left) and anticlastic (right) curvature 1988] Five main groups can be defined: curvature, surface point, edge, corner and undulation. The topic of “surface structure”/texture is less important for the scope of this thesis and is omitted. Curvature The curvature branch covers the classes plane, curved in one axis, synclastic and anticlastic. The mathematical terms anticlastic and synclastic are defined as follow (see Fig. 32) : “When the Gaussian curvature K is everywhere negative, a surface is called anticlast ic and is saddle-shaped. A surface on which K is everywhere positive is called syn Figure 33: convex (left) and concave (right) curvature clastic.”(http://mathworld.wolfram.com/Anticlastic.html) [wolfram.com Online 2005] The characteristic of convex or concave defines more subclasses where necessary (see Fig. 33). Further minor characteristics are the difference between curved/smooth and straight/faceted curvature (see Fig. 34) and a quantitative information about curvature direction change, e. g. once and many. The minor characteristics are implemented as sibling items. Edge The edge branch is divided in two main classes: ridge and valley. Ridge describes a curve Figure 34: curved/smooth (left) and straight/faceted (right) which changes a surface in a convex fashion. Valley describes the opposite change in curvature a concave fashion. In contrast to the above mentioned curvature the characteristic of straight and curved is more important for the one dimensional element edge. There fore the next taxonomy level split up ridges and valleys into straight and curved classes. Again the minor characteristic of quantity once and many is implemented as sibling
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items. Surface Point A surface point is a positive or negative projection of a point from a surface which also effects the surrounding surface. The surface point branch is dived into two main classes high point (positive projection) and low point (negative projection). This first subclass level is applied because of the architectural importance of the difference between a high point and a low point. The following subclasses describe other im portant characteristics of surface points: anticlastic, straight, synclastic, pointed, rounded and truncated. The minor characteristic of quantity once and many is implemented as Figure 35: various low and high points sibling items. The characteristic of branching (natural tree like objects) is of less importance for building shape and is not implemented (yet). Complex surface points in project items will often refer to more then one of this classes/items to describe their shape sufficiently. Corner Corners are formed by edges and surfaces. The shape of a corner is de termined by the number of edges and surfaces. At least one edge and one (curved) surface is required. [...] As with all forms there are also equivalent negative corners such as are found in the corners of rooms. Figure 36: One surface point vs. many surface points [Otto 1988]. Corner characteristics are closely dependant on the edges and surfaces involved. To avoid redundancy the corner main branch introduces only edge specific parameters like corner edge cardinality, positive or negative direction and a relative subjective item “signi ficant corner” which proved to be often sufficient to describe project shapes. One should keep in mind the difference between surface point and corner: A surface point does not necessary require an edge to be present as opposed to a corner. The transition between both definitions is blurred as it depends on the point of view of an user. For instance high points with edges could be interpreted as “corners” or “high points”. It depends on the perception. The corner edge cardinality class follows the usage of numbers in the polygon branch in the geometry 3D solid typology and offers distinct items from one to twelve and a many item to describe higher cardinality cases.
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Undulation Undulation is added as a main branch even though it is a cross section of certain as pects of curvature and edge. Undulation proves to be a valuable classification for build ings because it can describe foldable structures, wave-like and blob-like buildings.
Figure 37: Undulation vs. no undulation
Figure 38: Folded undulation vs. smooth undulation
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4.1.4. Truncation The truncation typology descries subtraction of parts of volumes. Together with the geometry 3D solid typology it can outline a lot of common project shapes. The term trimming is some times used in conjunction with curves and surface geometry and describes a similar process. A common definition of the term truncate is: 1 : to shorten by or as if by cutting off; 2 : to replace (an edge or corner of a crys tal) by a plane [Merriam-Webster Online 2005] Figure 39: Truncation - cardinality; one vs. many A starting point for this typology was truncation information by [Loh 1990], but the current state derived from internal revisions by the author. The truncation typology was rewritten more then once as it communicates a complex concept. The classification of scallop truncation was the trigger to rethink the first implementation. The current version is a split up. It follows the definition as introduced in this thesis: A typo logy is a well defined, consistent and closed set of data, while a catalogue is a collection of possible shapes with no demand to be exhaustive. Therefore a truncation typology is imple mented and it should be accompanied by a truncation catalogue in future research.
Figure 40: Truncation - curve type; straight segments vs. During revisions seven base parameters of truncation and one special case have been identi smooth curve fied: cardinality, curve type, facing direction, orientation, penetration, polygon match and quantity. The special case is polyhedral truncation and it requires three dimensional truncation related closely to Archimedean polyhedron solids (see chapter 4.2.3). The other parameters work in two as well as in three dimensional scenarios. A theoretical permutation of the seven parameters would lead to a huge amount of items. If one wants to order this items into a taxonomy the question which parameter is at the base of the hierarchy and which are placed deeper would arise. This leads to a theoretical weighting of the parameters, which would not necessarily correspond to applied truncation in project shapes. This kind of taxonomy would also introduce a lot of redundancy. This redundancy Figure 41: Truncation - facing; towards vs. away can not be solved with data graph as introduced in this thesis, because each permutation of the seven parameters is a theoretical valid unique truncation case. Therefore the author de cided to keep the truncation typology flat. It only describes the seven (plus one) parameter. The main branches are: • cardinality with two sub classes: one and many (see Fig. 39)
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• curve type with two subclasses: straight segments and smooth (see Fig. 40) • facing with two subclasses: towards and away (see Fig. 41) • orientation with three subclasses: horizontal, vertical and inclined (see Fig. 42) • penetration with four subclasses: convex, straight, concave and hole (see Fig. 43) • polygon match with two subclasses: partly and matching (see Fig.44) • quantity with three subclasses: minor, balanced and major (see Fig. 45) • special case polygonal truncation A truncation catalogue can utilise typology items to build up common combination. As cata logues are not required to be exhaustive only necessary combination found in project shapes could be the foundation of a truncation catalogue. The above-mentioned “scallop truncation” which can be found in the LSRU resources can now be defined as: many minor, smooth and concave truncations with its corners matching a Figure 42: Truncation - orientation; horizontal , vertical and inclined polygon in a vertical orientation. References into the arrangement typology about axes and sym metry could further narrow down the definition. A reference into the geometry 2D curve typo logy could describe the polygon in more detail (e. g. a regular hexagon) A truncation catalogue could introduce consistent use of “ground plan” or “contact surface” which is of special importance in architecture and is often involved in truncation. Scalloped truncation is mainly present in vertical orientation, so a catalogue could only implement this, and skip horizontal and inclined cases.
Figure 43: Truncation - penetration; convex, straight, con cave and hole
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4.2. Geometrical Typologies One main research community that deals with shape is Mathematics in its branch Geometry. Geometry – 1a: A branch of mathematics that deals with the measurement, proper ties, and relationships of points, lines, angles, surfaces, and solids; [Merriam-Web ster Online 2005] Interest in shape in the abstract field of Geometry is different to interest in the applied field covered by building professionals. Mathematics mostly describe geometry very preciously Figure 44: Truncation - polygon matching; partly vs. match and detached from real environment constrains like gravity and material. Still geometry ing serves as one of the main inspirational sources for architecture and is often a necessary tool to accomplish outstanding buildings. Geometrical typologies implemented in the building shape ontology offer an access to the widespread topic of mathematical geometry but are not exhaustive representations of the described subject. E. g. geometry 2D, as implemented, is sim ilar to Plane Geometry but its items could also exist in Non-Euclidean spaces like Spherical Geometry or in a UV coordinate system (a concept often implemented in 3D modelling ap plications to describe positions of textures and curves on a surface). The two main typologies are: Two-dimensional geometry; “Geometry 2D”: It is particular important in a day to day work flow of architects and engineers who often work with two dimensional representations of buildings such as ground plan, elevations and sections. The two main groups in this typology are angles and curves. Three-dimensional geometry; “Geometry 3D”: It can describe shape as a spatial object which is closer to real characteristics of buildings. The two main groups in this typology are geometry 3D solid and geometry 3D surface. A third minor group is spatial curve. Three-dimensional shapes are often defined by two-dimensional shapes therefore items from this typology refer to the Figure 45: Truncation – quantity; minor, balanced and ma geometry 2D items on many occasions. jor 4.2.1. Geometry 2D Angle The key resource for this branch is [Critchlow 1969]. An angle is the measurement of turn which takes place in a plane. More complex turns can be described by adding multiple angles from different planes. F. i. in Euclidean Geometry a complex turn is often described by its component turns in XY, XZ and YZ plane.
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This main branch defines common angle terms like right, acute, obtuse, etc. and also includes some significant angles (30, 45, 60, 72, 90, 180, 270 and 360 degrees). Significant angles are valu able in defining distinct common features in building shapes. (see Fig. 46)
4.2.2. Geometry 2D Curve The key resources for this branch are [maths.org Online 2005] and [wolfram.com Online Figure 46: 60 degree, 90 degree, obtuse and reflex angle 2005]. In the key resources and further literature there is some ambiguity about the terms “line” and “curve”. This ontology follows the idea that the term “line” means “straight line segment”. A line is a straight one-dimensional figure having no thickness and extending in finitely in both directions. A line is sometimes called a straight line or, more ar chaically, a right line (Casey 1893), to emphasize that it has no "wiggles" anywhere along its length. While lines are intrinsically one-dimensional objects, they may be embedded in higher dimensional spaces. (http://mathworld. wolfram.com/Line.html) [wolfram.com Online 2005] Line: An element of geometry that has only one dimension, its length. It has no breadth or width and is often thought of as a set of points that are so very closely set down there are no gaps between them. A line segment is usually part of a straight line between two given points on it [...] [maths.org Online 2005] The curve is used as a super class of possible straight or non-straight “one dimensional” ob jects. Therefore a line is a subclass (/special case) of a curve in this thesis. As we speak of “curve” we mean a “curve segment” due to the scope of the ontology which deals with finite real world environments for buildings. (see also infinite axes in the arrangement typology) Curve: A line which may be straight or not; [maths.org Online 2005] One special topic are spatial / space / skew curves which are part of the geometry 3D typo logy. The curve branch demonstrates one typical aspect of data graphs which differs from tradition al hierarchies (see chapter 7). Some classes like circle have more then one super class as they can be seen as an important basic type of a curve and a special case of an ellipse, closed curve and Figure 47: Conic section [wolfram.com Online 2005] conic sections. The concept of conic section is a visual approach to describe the relationship between the basic curves: circle, ellipse, parabola and hyperbola as depicted in Figure 47.
“Building Shape Ontology” by Philipp Jurewicz 38 4. Shape Typologies
Curves deriving form conic section are also important for geometry 3D surface as they define the “quadratic surfaces” group. One major subclass is the polygon branch: A closed plane figure with n sides. If all sides and angles are equivalent, the poly Figure 48: Regular tessellation gon is called regular. Polygons can be convex, concave, or star. The word "poly gon" derives from the Greek poly, meaning "many," and gonia, meaning "angle." The most familiar type of polygon is the regular polygon, which is a convex poly gon with equal sides lengths and angles. (http://mathworld.wolfram.com/Poly gon.html) [wolfram.com Online 2005] The geometry 2D typology offer subclasses for three sided up to twelve sided polygons with their Greek names (e. g. pentagon, hexagon, heptagon, etc...). Each of these classes have a sub Figure 49: Semiregular tessellation class which describes the regular version of the polygon. A regular polygon is an n-sided polygon in which the sides are all the same length and are symmetrically placed about a common center (i.e., the polygon is both equiangular and equilateral). (http://mathworld.wolfram.com/RegularPoly gon.html) [wolfram.com Online 2005] Special cases are the triangle and the quadrangle. The triangle has additional prominent sub Figure 50: Irregular tessellation classes like right-angled, isosceles and obtuse. The quadrangle has detailed deep subclasses because of its significance for building shape (see Fig 18): trapezoid, diamond, parallelogram, rhombus, rect angle and square. Polygons with an even amount of points can be assembled by using only right angles. Beside of the rectangle the other are all concave polygons and have at least one 270 degree angle. The tiling of a plane into smaller polygons is called tessellation. There are exactly three types of “regular tessellation”, based on equilateral triangle, square and regular hexagon (see Fig. 48). In “semiregular tessellation” at least least two regular convex polygons form the pattern Figure 51: oblique circular cone (left); right circular cone (see Fig. 49). “Irregular tessellation” covers all other plane tiling where no gaps appear (see (left) Fig. 50). The concept of polygon tessellation can be extrapolated into the third dimension and is called “close packing”. The three dimensional close packing can be used to describe spatial arrangements of building shapes as described in chapter 4.1. 4.2.3. Geometry 3D Solid The geometry 3D solid typology introduces many shapes that are very common in spoken lan guage. It interprets shapes as volumes that are filled with a solid material.
Figure 52: oblique elliptical cylinder (left); right circular cyl inder (right) “Building Shape Ontology” by Philipp Jurewicz 39 4. Shape Typologies
A closed three-dimensional figure (which may, according to some terminology con ventions, be self-intersecting). Kern and Bland (1948, p. 18) define a solid as any limited portion of space bounded by surfaces. Among the simplest solids are the sphere, cube, cone, cylinder, and more generally, the polyhedra. (http://math world.wolfram.com/Solid.html) [wolfram.com Online 2005] The solid volume can be seen as the internal building space of a building. The key resources for this typology are [Critchlow 1969], [maths.org Online 2005], [wolfram.com Online 2005] and [Otto 1988] . The main branches are cone, cylinder, ellipsoid, sphere, torus, polyhedron and freeform. A “geometry Figure 53: Ellipsoid, oblate spheroid, prolate spheroid and 3D type” main branch offers a different access to the main branches and polyhedral sub sphere branches. Cone and Cylinder The cone and cylinder main branches follow the same pattern. Their next branching level splits up into oblique and right cone/cylinder. Within the oblique class items cover circular, elliptical and scalene variations. Within the right class only circular and elliptical variations are considered (see Fig. 51 and 52). The similarities between cone and cylin der can also be seen in the geometry 3D surface typology. Ellipsoid and Sphere The ellipsoid and the sphere are closely related shapes as they only differ in the length of their axes. A ellipsoid has three different length axes. The shape in between ellips oid and sphere is called spheroid and has two equal axes. A sphere has all equal axes. A spheroid can be seen as a special case of an ellipsoid and a sphere as a special case of a spheroid. This is reflected in the subclasses of the ellipsoid branch. Because of the fun Figure 54: ring torus (left); horn torus (right) damental significance of the sphere, the sphere class is not only a subclass of a spheroid and torus but also a main branch of the typology (see Fig. 53) Torus and Sphere A torus is generally identified as a separate main branch. It can better be described with surface geometry (see next chapter) but is also included in the geometry 3d solid typology for completeness. The subbranches describe the different offsets of the circle that defines the torus by revolution. This results in a ring torus, a horn torus and a spindle torus. The sphere can be seen as a very special case of a torus where the offset reaches zero. (see Fig. 54 and 55)
Figure 55: spindle torus (left); sphere (right)
“Building Shape Ontology” by Philipp Jurewicz 40 4. Shape Typologies
The polyhedral main branch is the biggest main branch in the geometry 3d solid typology. On the one hand this is due to the fact that it consists of some well formulated mathematical families and on the other hand this branch is to some importance for a building shape ontology as it covers a big portion of common buildings in our environment. Subbranches are prism, pyramid, antiprism, finite polyhedron and geodesic polyhedron Prism and Pyramid A general prism and pyramid as defined in this typology derive from a polygon that is Figure 56: oblique regular prism and oblique regular pyram being extruded without or with scaling along a straight path. This is very close to the id way a cylinder and a cone are created and actually only differs in the parameter of the two-dimensional shape. Therefore the next subclass level is similar: we have oblique and right prisms/pyramids. The next sub class level though only applies for prisms and pyramids as it deals with regularity of the shape. This definition is present in the two- dimensional polygon as well as three-dimensional polyhedron classes. This duplica tion reflects the importance of regular prisms/pyramids for buildings. The items inside the classes represent the number of base sides of the prism/pyramid. Numbers from three to twelve are available as distinct items while a general “multi sided” item can be assigned if the number of sides exceeds twelve. Figure 57: right pentagonal prism (left) right and regular The right prism class includes one additional item: the cuboid which is regular but in pentagonal prism (right) slightly different sense then the items in regular prism class. Antiprism The antiprism main branch defines a special polyhedral shape. It is closely related to a prism but must be considered separately as it does not follow the main rule of a prism which only deals with parallel translation of a two dimensional polygon. (see Fig. 58) A solid that has two opposite faces which are identical to one another, but unlike a prism, these two faces are rotated so that their vertices are Figure 58: right and regular octagonal prism (left) octagonal not lined up. So every other face of the antiprism is a triangle. An anti antiprism (right) prism with triangular bases is an octahedron. [maths.org Online 2005] Platonic, Archimedean and Catalan Solid The branch finite polyhedron groups platonic, archimedean and catalan solids. The well known platonic solid class defines the tetrahedron, hexahedron, octahedron, dodecahedron and the icosahedron. The archimedean class defines 13 solids that derive from platonic solids Figure 59: Platonic solids: tetrahedron, [cube skipped], oc when one applies polyhedral truncation on them. The catalan class defines 13 solids that tahedron, dodecahedron and icosahedron
“Building Shape Ontology” by Philipp Jurewicz 41 4. Shape Typologies
derive from platonic solids when one applies polyhedral stellation on them. This thesis follows the relationship diagrams from [Emde 1977] to show the connec tion between the platonic and the archimedean/catalan solids. Therefore hexahedron and dodecahedron (both platonic) are subclasses of “expanded tetrahedron” (catalan) and octa hedron and icosahedron (again both platonic) are subclasses of “truncated tetrahedron” Figure 60: Simple Archimedean solids: truncated tetrahed (archimedean). This morphological linking helps the user to understand visually the re ron, (truncated cube skipped) and truncated octahedron lationships between this three solid families. Platonic solids are also sub classes of other typologies. E. g. the tetrahedron is a pyramid, while the hexahedron (aka cube) is a subclass of regular prisms. The platonic solids are the base for geodesic polyhedral and appear as “frequency 1” (and the cube even as a “frequency 2”) geodesic polyhedron (see below).
Figure 61: Simple Archimedean solids: truncated dodeca hedron and truncated icosahedron
Figure 62: Simple Catalan solids: expanded tetrahedron (expanded cube skipped) and expanded octahedron
Figure 63: Simple Catalan solids: expanded dodecahedron and expanded icosahedron “Building Shape Ontology” by Philipp Jurewicz 42 4. Shape Typologies
Geodesic Polyhedron The term “geodesic dome” is ambiguous defined by various sources. The following distinction is used in this thesis. A geodesic sphere is defined by the projection of the vertices and the edges onto the sphere surface. A geodesic polyhedron pro jects only the vertices onto the sphere surface. The edges remain straight lines. The resulting shape is not a sphere but rather an approximation. The term “geodesic domes” is used inconsistently to describe both concepts. A Figure 64: A platonic icosahedron and its frequency 5 geodesic sphere has the “shape of a sphere”. This section covers geodesic polyhedra. Ar geodesic polyhedron chitects use the approximation of the geodesic polyhedra as a “feature” to build dome structures from linear elements. A geodesic dome[/polyhedron] is a triangulation of a Platonic solid or other polyhedron to produce a close approximation to a sphere (or hemi sphere). The nth order geodesation operation replaces each polygon of the polyhedron by the projection onto the circumsphere of the order-n regular tessellation of that polygon. Figure 65: frequency 1 to 4 of icosahedron based geodesic (http://mathworld.wolfram.com/GeodesicDome.html) [wolfram.com On polyhedra (class method) line 2005] Three subclasses are implemented: tetrahedron, octahedron and icosahedron based geodesic polyhedron. Each of these splits up in “class 1” and “class 2” sub classes, which are two different mathematical ways to create geodesic polyhedra. “class 1” can have odd and even frequencies while “class 2” can only have even frequencies.
Figure 66: frequency 2,4,6 and 8 of hexahedron based Frequencies from one to eight for “class 1” and two, four, six and eight for “class 2” geodesic polyhedra (class 2 method) are implemented as sibling items. A “many” item can describe cases with a frequency higher then eight, which are rare in architecture. Because there is no limit for fre quencies, geodesic polyhedron can not be considered to a subclass of finite polyhedron. Freeform Solid The freeform main branch in the geometry 3d solid typology covers irregular solids that are not described by the above-mentioned main branches. Geometry 3D Type This main branch makes it possible to look at cone, sphere, ellipsoid, sphere and the poly hedron subclasses prism, antiprism, pyramid, finite polyhedron and geodesic polyhedron under a different aspect. This grouping is a variation of the directional/concentric concept used by [Loh 1990]. It splits up the concentric group into a radial and a focus point
“Building Shape Ontology” by Philipp Jurewicz 43 4. Shape Typologies
group. Cone and pyramid have a common characteristic which is a focal point, but they are concentric and directional. Cylinder, prism and antiprism have in common that they never hit their pivot point. They can be extended infinite while remaining “par allel”. Sphere, ellipsoid, finite polyhedron and geodesic polyhedron have a spatial radial point in common. In architecture smooth shapes are often split up into straight segments to be build able. The transition between a cone and a pyramid with many faces is blurred. This branch allows to group the shapes of the geometry 3D solid typology according to this characteristics so we can infer a relationship between a cone and a pyramid. As a side note one can mention that the torus does not fit in any of the groups above.
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4.2.4. Geometry 3D Surface Geometry 3D solid combined with truncation can describe the main proportion of today's build ings but there are still some gaps how to describe some project shapes. Especially the field of lightweight structures and some architecture theories that utilise tool sets offered by 3D com puter graphic software use a different visual language. These project shapes can be described more adequately by their surfaces. Surface: A set of points in three dimensions, on which position can be specified us Figure 67: generalised cone (left); generalised cylinder ing two parameters (ie if you are at any point on a surface, there are two inde (right) pendent directions in which you can move). A surface is often the boundary of a solid, or part of such a boundary. We can also think of a surface as the result of continuously deforming (bending, twisting, etc.) a part of a plane. [maths.org On line 2005] The shape ontology has two surface typologies: First a general “surface” typology based on [Otto 1988] which follows more a descriptive language of identifying features and character istics of shape (see chapter 4.1.3). Second this “geometry 3D surface” branch which looks at surface from a mathematical point of view. The key resources for this branch are [wolfram.com Online 2005], [Joedicke 1962] and [maths.org Online 2005]. The first level of subclasses are major geometrical surface families like “surface of Figure 68: right conoid on arch (left) Möbius strip (right) revolution”, “ruled surface”, “minimal surface”etc. They represent fundamental geometric characteristics that their subclasses have in common. But they are not disjoint: A sub class can appear in more then one surface family when it contains the necessary characteristics. F. i. a cone surface is a surface of revolution, ruled surface, quadratic surface and generalized surface. A hyper bolic paraboloid is a surface of translation, ruled surface, quadratic surface and saddle surface. Multiple super class surface shapes are of special interest to building professionals as they offer a com bination of geometrical handling, constructable generation, structural features and aesthetic aspects [Joedicke 1962]. The implemented surface families are: Generalised Surface In surface geometry the term “generalised” (sometimes only ”general”) is used to de scribe the most basic concept of shapes which are “misused” in common language. F. i. the basic concept of a generalised cone is a common vertex / focal point within a
“Building Shape Ontology” by Philipp Jurewicz 45 4. Shape Typologies
ruled surface, while a generalised cylinder is missing this focal point (see Fig. 67). The shapes do not even need to be closed. The terms cone (surface) and cylinder (sur face) as we use them in normal language are constrained sub classes of the general ised versions. Further subclasses are generalised hyperboloid, generalised paraboloid and generalised helicoid. Ruled Surface “A ruled surface is a surface that can be swept out by moving a [straight] line in space” [wolfram.com Online 2005]. Ruled surfaces are important for building shapes, as they can be built with planar segments. The generalised cylinder can even be build with planar strips. Further prominent subclasses are generalised cone, right conoid and Möbius strip (see Fig. 67 and 68 ). The conoid in Figure 68 is already a special case of right conoid but these kind of conoids are familiar in architecture and are called right conoid on arch in this classification. Figure 69: hyperbolic paraboloid (left); one sheeted hyper boloid (right) A special sub class is the doubly ruled surface, as it can be constructed of two layers of parallel straight elements [Joedicke 1962]. The three subclasses are plane, hyperbolic paraboloid and one sheeted hyperboloid (see Fig. 69). Surface of Translation A surface of translation results when a planar profile curve is swept along a rail curve. The instances of the profile curve must be parallel to each other. Generalised cylinders and hyperbolic paraboloid are prominent subclasses. In this case the hyperbolic paraboloid is interpreted as a profile parabola swept along a rail parabola with a opposing curvature and perpendicular to the profile curve. (see Fig.69 (left)). Surface of Revolution A surface of revolution can be generated by rotating a planar curve about an axis. Cross sections always consist of circles and the surface has radial symmetry. Prominent sub classes are right circular cone, right circular cylinder, torus, paraboloid and hyperboloid (see Fig. Figure 70: ring torus (left); circular paraboloid (right) 70). Minimal Surface Minimal surfaces are defined as surfaces with zero mean curvature. [...] Minimal surfaces may also be characterized as surfaces of minimal sur face area for given boundary conditions. A plane is a trivial minimal sur face, and the first nontrivial examples (the catenoid and helicoid) were
“Building Shape Ontology” by Philipp Jurewicz 46 4. Shape Typologies
found by Meusnier in 1776 (Meusnier 1785). The problem of finding the minimum bounding surface of a skew quadrilateral was solved by Schwarz (1890). (http://mathworld.wolfram.com/MinimalSurface.html) [wolfram.com Online 2005] The simplest minimal surface is a plane. The circular helicoid is related to staircases in architecture (see Fig. 71) From a mathematical point of view minimal surfaces are a complex construct. Archi tects and geodesics researchers often use physical models (soap films, nylon, etc.) and alternative computer concepts to determine “Buildable (nearby) minimal sur faces”. This process is often called “form finding”. A major contribution to this field came from Frei Otto and his research team.
Figure 71: plane (left); circular helicoid (right) One common misconception from architects is to believe that the ruled surface of a skew quadrilateral or a hyperbolic paraboloid is equivalent to the minimal bounding surface. Quadratic Surface This family has the common characteristic that each intersection with a plane results in a (proper or degenerated) conic section or a straight line. Conic sections are: circle, ellipse, parabola and hyperbola. For the lay viewer, shapes from this family has obviously something visual in common which is hard to describe. A more detailed mathematical definition is: Quadratic surfaces are also called quadrics, and there are 17 standard- form types. A quadratic surface intersects every plane in a (proper or de generate) conic section. In addition, the cone consisting of all tangents from a fixed point to a quadratic surface cuts every plane in a conic sec tion, and the points of contact of this cone with the surface form a conic section (Hilbert and Cohn-Vossen 1999, p. 12). (http://mathworld. wolfram.com/QuadraticSurface.html) [wolfram.com Online 2005] Figure 72: hyperbolic paraboloid (left); monkey sattle sur face (right) This family includes the majority of surfaces implemented in the current typology. Saddle Surface Saddle surfaces contain anticlastic curvature (see Fig. 72). Non-Orientable Surface A surface such as the Möbius strip or Klein bottle (Gray 1997, pp. 322- 323) on which there exists a closed path such that the directrix is re
“Building Shape Ontology” by Philipp Jurewicz 47 4. Shape Typologies
versed when moved around this path. (http://mathworld.wolfram.com/NonorientableSurface.html) [wolfram. com Online 2005] (see Fig 68 right) Freeform Surface This subclass exists if an user wants explicitly to state that a surface was created without specific geometrical surface rules in mind. Still if such a surface was created digitally there are often underlying surface generation concepts like “non-uniform, rational B-splines” (NURBS) surfaces, smooth poly surface or subdivision surfaces. 4.2.5. Geometry 3D Spatial Curves Figure 73: helix on a cone surface (left); helix on a cylinder surface (right) A curve which may pass through any region of three-dimensional space, as contras ted to a plane curve which must lie in a single plane (http://mathworld.wolfram. com/SpaceCurve.html) [wolfram.com Online 2005] Synonyms are space curve and skew curve. At the moment the geometry 3D spatial curve typology is very small as it only has two main branches: helix and freeform. Literature is not consistent about the distinction between spiral and helix. This typology as sumes that a helix is spatial while a spiral is a two dimensional curve. When a helix does not scale inwards it lies on the surface of a cylinder, otherwise on the surface of a cone. In its broad definition a helix is a inclined “curve on surface” and can exist on many surface classes. (see Fig. 73 and 74) Figure 74: helix on a sphere surface (left); helix on a para boloid surface (right)
“Building Shape Ontology” by Philipp Jurewicz 48 5. Shape Catalogues
5. Shape Catalogues Preparation work for this thesis showed that it is hard to merge the SDA shape table (see chapter 2.2.2) with geometrical and general classifications as described in chapter 4 “Shape Typologies”. But the benefit of the SDA shape table is evident as it can classify a wider vari ety of projects and group them as pure geometrical typologies are able to. Therefore one as sumption of this thesis is: The domain of architecture incorporates many aspects into buildings. Therefore the point of view varies under which we investigate building shape and a single classification cannot cover all these aspects without losing its own consistency to a significant degree . A shape ontology Figure 75: Some SDA cone shape members can be used as an integration approach that allows different point of views to coexist but still refer to each other. A (shape) catalogue is a collection of possible idealised building shapes focusing on specific aspects. Catalogues serve a purpose. The internal classes, items and properties of catalogues have a layout for a specific task such as timber construction, membrane structures or social aspects of buildings etc. . Catalogues can be assembled with a specific set of projects in mind. This is legitimate be cause catalogues do not claim to be complete and exhaustive collections, they are rather pur pose driven. Figure 76: Some SDA cone shape members 5.1. SDA Building Shape Catalogue The SDA Building Shape catalogue derives form LSRU work as described in chapter 2.2. The layout is based on solid objects. The main branches are: cone, cylinder, dome, polyhedron, prism, pyramid and vault. As stated before we can observe that cone, cylinder, polyhedron, prism and pyramid are similar to shapes that are defined in geometry 3D typologies. Dome and vault are modified geometry shapes, but they are very common architecture shapes. The sphere often regarded as a basic geometry object can be seen as a special kind of dome, as only a few full sphere examples have been build. The branches contain from 15 up to 74 items.
Figure 77: Some SDA prism shape members The items follow an architectural point of view of this basic shape. Figures 75 and 76 shows that some members of the cone branch would not be qualified as cones from a geometrical point of view. But in research work of the LSRU this shapes have parameters in common
“Building Shape Ontology” by Philipp Jurewicz 49 5. Shape Catalogues
that make it logical to group them. These parameters can derive from a perception point of view, where a certain visual relation can be recognised. They can derive from other aspect of buildings like structure, material or construction. Or they can derive from one rule often applied in the LSRU classification: The outer building shape is defined by the space that is covered by an object. If sides of the object are open or cantilevered the below space is considered part of the volume and therefore part of the building shape. An example are double curved shapes that are mostly defined by surface and not volume. As Figures 77 and 78 shows, the prism branch includes such items. Figure 78: Some SDA prism shape members One parameter which is not represented in the taxonomy of the catalogue is the distinction between concentric and directional shapes. As this is clear for the main shape units (see Fig.79), it becomes harder to be consistent for all items within a branch. For instance regular right prisms can be either identified as directional and concentric shapes. The same applies to vertical cylinders. Often aggregate shapes can have both parameter regarding to the point of view (e. g a linear sequence of overlapping domes). Though this characteristic is implemented in a related way in the geometry 3D solid typology. (see chapter 4.2.3) Items in this catalogue are defined according to parameters like 3d geometry solid shape, arrange ment, cardinality, curvature, etc.. The definitions are established with property links with items from various typologies. Still this catalogue is generic and the shapes represent only proto types. In real buildings, project shape is often not so idealised and additional volumes are ad ded or deducted. An user who adds projects into the ontology should not be to strict when a project shape does not match perfectly with a catalogue shape as variety in real world will al ways be bigger then in generic catalogues. Again the rule should be: If it suits the research that a project item is connected with a catalogue item then the link should be established. 5.2. Possible Further Catalogues Ground Plan Catalogue During editing of example building projects for this thesis it became evident, that the ontology would benefit from a common ground plan catalogue. While a lot of sec tions could be identified as geometry 2D items the ground plan of buildings is often an aggregate of more then one geometry 2D item. In many cases arrangement information Figure 79: Definition of directional and concentric shapes by can also be identified in the ground plan, even though it doesn't propagate clearly in LSRU
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the spatial shape of a project. The fact that buildings are built on a predominant horizontal or only slightly inclined piece of land backs the importance of the ground plan for architecture and would help to bridge towards urban design. Drawing work in most design studios is based on 2D sketching software applications with 3D “add-ons”. Therefore there is still a lot of thinking and communication in “plan”, “section” and “elevation” in this profession, which should be taken into ac count. Modified SDA Shape Catalogue Based on the analysis of the SDA and the entered example projects it would be pos sible to create a modified SDA shape catalogue. It would follow the same basic pat tern as the existing SDA shape catalogue, by using cone, cylinder, dome, prism, pyramid and vault as the main branches, but it could be modified to better match the example projects and the existing 400 SDA projects. Due to the distinction between typology shape and catalogue shape it would be pos sible to skip many of the polyhedral items, as they are already defined in the geometry 3D solid typology. Membrane Shape Catalogue Stressed membranes have a distinct visual language and they follow a certain set of rules which are different from traditional buildings. Parameters that drive the shape of a membrane are topology of the ground, point and linear edge support, point and linear internal support, material and air pressure for air supported systems. The LSRU researched the morphology of membrane shapes and a classification of mem branes was developed as an illustrated catalogue with sketches and photographs of models. This work could be integrated as a new catalogue into the shape ontology. One could extend this approach to cover not only membranes but also load-derived /form-active shapes like grid shells, suspension systems and tension (concrete) shells. This topic should benefit from today's computer simulations that make it possible to produce many variations of membranes in a reduced amount of time. There is re lated research by [Wehdorn-Roithmayr 2003] at Vienna University of Technology
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which could be utilised . An implementation of such a catalogue would bridge towards structures and civil engineering. Building Profiles Building profiles have been used by [Joedicke 1977] in investigations how architec tural perception of buildings can be formulated and how the perceptions varies between experts and laymen /casual users. The researchers asked users to rate build ings according to term pairs like “hard-soft”, “narrow-wide”, “open-closed”, “fra gile-solid” etc. and used statistic methods to analyse the results. This research has some cross faculty potential, as it looks at buildings not only from a technical point of view but rather from a social one. Due to available data from the seventies, some comparison on how architectural perception in society changed over time could be investigated. Recent activities at ITI revitalised this approach and could be combined with the shape ontology [Pfeiffer-Rudy 2005] Truncation Catalogue Please see the discussion in chapter 4.1.4
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6. Projects Test Cases This section visualise three project shapes and their connection to catalogue and typology shape information. The first example “Japanese Pavilion, Expo Hannover” is illustrated twice. The first page shows the connections from the pavilion example to the catalogues and typologies. The second page shows the connections back into other project shapes. The computer tries to rate the match and returns other project shapes in an order. This is an experimental feature of the web application to demonstrate technical potential for further development and the results should not be taken to seriously. Having said this, interesting pattern between archi tecture projects can be recognised. The Japanese pavilion is a good example how catalogues and typologies can play well together. The Multihalle Mannheim test case handles amorph blob like project shapes. An interesting detail is that the project shape “overrides”/doubles two typology connections which are already established by the catalogue shape. This can be done to emphasise that something is e. g. only a “secondary” shape or a important “primary” one, like the blob-like overlap char acteristic. The Ufa Cinema test case illustrates, that it is possible to classify project shapes with no cata logue shape available. Also the deconstructivistic visual language can be mapped to some de gree into shape characteristics form the ontology. The three examples are just a selection of projects which are entered as test cases into the web application. Some other interesting project shapes on the CD-ROM are: • The Ice Skating Tent in Munich with its form active anticlastic roof, strong arc and symmetry. • The “Blob” part of the Kunsthaus Graz with its pointing windows • The Natural Eclipse House with its cocoon shape and its low point • The Australian RIAA pavilion with its one sheeted hyperboloid shape
“Building Shape Ontology” by Philipp Jurewicz 53 6. Projects Test Cases
Japanese Pavilion, Expo Hannover (page 1)
“Building Shape Ontology” by Philipp Jurewicz 54 6. Projects Test Cases
Japanese Pavilion, Expo Hannover (page 2)
“Building Shape Ontology” by Philipp Jurewicz 55 6. Projects Test Cases
Multihalle Mannheim
“Building Shape Ontology” by Philipp Jurewicz 56 6. Projects Test Cases
Ufa Cinema Dresden
“Building Shape Ontology” by Philipp Jurewicz 57 7. Digital Data Concepts
7. Digital Data Concepts This section will give a brief overview of data organisation by describing the differences between data table, data hierarchy and data graphs. This is followed by a brief introduction to ontologies and semantic web technology. It closes with a description how these concepts can be applied on the shape ontology. 7.1. Tables, Hierarchies and Data Graphs The three fundamental concepts on data organisation are table, hierarchy and data graph. The same information can often be stored in two or even all three implementations of these base concepts. So the decision for a particular concepts should be driven by the Figure 80: schematic view of a table and a tree application/purpose of the data.
Data Tables Data tables arrange data in columns for each variable and rows for each data set (see Fig.80 , left). Their organisational focus is to query rows with e. g. similar, ascending or descending variables. Links between different rows can be establish by using spe cial key values that point to each other. The connection of tables makes a database “relational” and is symbolised by database schemas. Relational databases are a very mature technology and the most common way how structured data is stored nowadays. One drawback of tables is that all data row consist of all variables even when some variables are not logically necessary for each data row. Beside of visual problems with a sometimes bloated grid layout it can also lead to false assumptions that some values are missing. It is possible to solve such table layout drawbacks by introducing more relational table connection, but the price is greater complexity. For instance the use of a entity-relational (ER) model can abstract the data base towards a conceptual model (described below). Taxonomies / Hierarchies Figure 81: schematic view of a data graph Taxonomies and hierarchical data organisation can be illustrated as a tree with branches and the focus is on parent-child relationship of two data sets (see Fig.80, right). A prominent implementation of hierarchical data is the XML specification [w3 consortium Online 2005] which provides a way to store semi-structured inform
“Building Shape Ontology” by Philipp Jurewicz 58 7. Digital Data Concepts
ation and query it with some standardised tools. With tehnologies like XLink and XPointer [w3 consortium Online 2005] it is possible to establish links between data sets but the focus remains on the directly implemented parent-child relationship. Hierarchical data organisation gained a lot of momentum in recent years because it proves to be a good solution for semi structured information like web pages, word processing data and configuration files and it is flexible as an exchange format. Dis advantages are higher computing demands and the strict focus on only one parent- child relationship, which can lead to repeating sub branches that can bloat a tree and makes it hard to maintain. As with tables this can be partially solved by introducing more complexity. Data Graphs
Data graphs are related to hierarchies but one important difference is that they allow directed and undirected connection between nodes which can be depicted in node- and-edge diagrams. It is also possible to have more then one super class for a specif ic member and it is not necessary to have a root object. There is no theoretical limit ation for the number of edges, therefore it is easier to create multiple overlaying taxonomies for different point of views of a domain. (see Fig. 81) The current draw Figure 82: schematic view of tree, directed acyclic graph backs of data graphs are that they require more computing logic to handle its fea and directed cyclic graph (box: node; arrow: directed edge) tures (e. g. the possible cycles/loops in a node-and-edge path, see Fig.82 ) and common users are not necessary familiar with this organisation. Even though the World Wide Web “browsing experience” follows a similar pattern. 7.2. Ontologies and the Semantic Web This paper uses the term “shape ontology” so we need to understand what is meant by “on tology” in the context of this paper. We can repeat the definition as in chapter 1.2: A body of formally represented knowledge is based on a conceptualization: the ob jects, concepts, and other entities that are assumed to exist in some area of in terest and the relationships that hold among them (Genesereth & Nilsson, 1987) . A conceptualization is an abstract, simplified view of the world that we wish to repres ent for some purpose. Every knowledge base, knowledge-based system, or know ledge-level agent is committed to some conceptualization, explicitly or implicitly. An ontology is an explicit specification of a conceptualization.[Gruber 1993] While this is a well formulated and often quoted definition it still leave a few details open for
“Building Shape Ontology” by Philipp Jurewicz 59 7. Digital Data Concepts
our purpose. The term “ontology” is overstretched in its meaning and the spectrum can range from taxonomies, thesauri, conceptual models up to logical theories. What is normally known as an ontology can thus range from the simple notion of a taxonomy (knowledge with minimal hierarchic or parent/child structure), to a thesaurus (words and synonyms), to a conceptual model (with more complex know ledge), to a logical theory (with very rich, complex, consistent, meaningful know ledge). [Daconta, Obrst & Smith 2003]. Taxonomies, as mentioned before cover hierarchical information. Thesauri add equivalence, homographic and associative information. Conceptual models try to capture the semantics and meaning of information. They add detailed properties, so instead of an imprecise “see also” as in thesauri, we have “has geometry 3D” or “is surface of” properties which describe the association in more detail. Conceptual models also introduce constrains (e. g.: if something is a general cone surface it can not be a general cylinder surface, therefore these classes are “disjoint”). If a conceptual model stays inside certain condition called “description logic” we can use reasoner software that can infer additional information from the existing asserted one. Logical theories are at the end of the ontology spectrum and they represent in formation which is mature, meaningful, machine-interpretable and consistent. Ontologies use taxonomies as their backbone but based on data graphs and they try to give semantic interpretation to data. Ontologies [ / conceptual models] try to limit the possible formal models of inter pretation (semantics) of those vocabularies to the set of meanings you intend. None of the other model types with limited semantics—taxonomies, database schemas, thesauri, and so on—does that.[Daconta, Obrst & Smith 2003] A good way to understand what ontologies try to achieve is to compare their highest state, the logical theories, with thesauri: An ontology [/logical theory] , however, does try to represent the complex se mantics of concepts and the relations among concepts, their properties, attributes, values, constraints, and rules. But then, the purpose of an ontology is quite distinct from that of a thesaurus. An ontology does try to capture and represent the mean ing of a domain, a set of domains, or the entire world, because it attempts to expli citly simulate the meaning that a human being has in his or her mental model of the domain, set of domains, or the world. Furthermore, an ontology is meant to be used directly by many kinds of software applications that have to operate on and so have knowledge about the domains represented by the ontology—including some times applications that have not yet been thought of. Finally, an ontology is meant to be extended, refined, and reused, traits that it shares with its semantically weak er cousin, the thesaurus. Unlike the thesaurus, however, an ontology tries to ex
“Building Shape Ontology” by Philipp Jurewicz 60 7. Digital Data Concepts
press precise, complex, consistent, and rich conceptual semantics. [Daconta, Obrst & Smith 2003] The shape ontology in this thesis and at current stage of implementation could be positioned between thesauri and conceptual models. It already uses detailed properties like “has geo metry 3D” and “is dual of”(for polyhedra), but does not have enough constrains implemen ted yet to make the information fully machine-interpretable. It is intended to use limited reasoning in future implementation. For instance if the number of catalogues increase and an user enters information with focus on one catalogue, the software should infer that the refer ences this user made by linking to his catalogue items and some typology items equals the definition of a catalogue item in a different catalogue. The vision of the paradigm change how data is organised and shared can be constituted by the “semantic web”. Tim Berners-Lee is head of the w3 consortium, the leading institution for standards for the Internet and recently formulated this vision in some interviews The goal of the Semantic Web initiative is to create a universal medium for the ex change of data where data can be shared and processed by automated tools as well as by people. The Semantic Web is designed to smoothly interconnect personal in formation management, enterprise application integration, and the global sharing of commercial, scientific and cultural data. We are talking about data here, not human documents. The Semantic Web is not about the meaning of English documents. It’s not about marking up existing HTML documents to let a computer understand what they say. It’s not about the artificial intelligence areas of machine learning or natur al language understanding -- they use the word semantics with a different meaning. It is about the data which currently is in relational databases, XML documents, spreadsheets, and proprietary format data files, and all of which would be useful to have access to as one huge data base.[Berners-Lee 2005] The bridge back to data graphs and the shape ontology can be seen as follow: The reason ontologies are becoming popular is largely due to what they promise: a shared and common understanding of a domain that can be communicated between people and application systems. [Berners-Lee 2004] If we wish, however, to have the computer assist in the dissemination of the know ledge embedded in a document—truly realize the Semantic Web—we need to at least partially automate the semantic interpretation process. We need to describe and represent in a computer-usable way a portion of our mental models about spe cific domains. Ontologies provide us with that capability. This is a large part of what the Semantic Web is all about. [Daconta, Obrst & Smith 2003]
“Building Shape Ontology” by Philipp Jurewicz 61 7. Digital Data Concepts
7.3. How shape organisation benefits from data graphs When we examine the shape ontology we can find many examples where data graphs helped to keep the data logical and consistent. For instance the geometry 3D surface typology has items like the hyperbolic paraboloid which has four super classes: doubly ruled surface, quadratic surface, saddle surface and surface of translation. Also what we commonly call “cone surface” has also multiple super classes: circular cone surface, closed cone surface, one sheeted cone surface, right cone surface (all four have the super class generalised cone surface in common) and surface of revolution. This kind of organisation makes it possible to classify shapes which are not perfect cone surfaces. Still these shapes would be indirectly associ ated with the common cone surface as they are very close in terms of data graph nodes and edges. The property “is dual of” is only available to the finite polyhedron class and its subclasses platon ic, archimedean and catalan solids. Other parts of the ontology are not cluttered by this very spe cialised property. The nodes in the ontology OWL file itself are separated into three groups: • The “shape” node consist of the main trunk of what is referred to as the “shape on tology” throughout this thesis. Beside of the SDA shape catalogue, the catalogue node consist of some rough draft versions of future catalogues like truncation. • The “project shape by category”node provides meta data like location, climate and application which eases access to the project shapes. This meta data is used for bet ter usability by the web application. The content is not focus of this thesis. • The “internal data” node´is the super class of some secondary data.
“Building Shape Ontology” by Philipp Jurewicz 62 8. Digital Media
8. Digital Media This section describes briefly the SDA as a starting point for the media usage in the shape ontology followed by a brief outline how the visualisation pipeline was set up. It closes with a review about 3D-web-plug-ins which have been considered for this project. Digital media usage in this thesis is inspired by the LSRU resources “Structural Design Aid” (SDA) and “SDA Behaviour” (see chapter 2.2 ). Both resources already take advantage of di gital media capabilities: They introduce a separate image database, which allows the associ ation of a none limited amount of images to each project and Quicktime animations for load cases to follow deformation of idealised structural models The SDA and SDA Behaviour also take advantage of the Internet where view space is not Figure 83: camera positions; top row: bird eye in grey scale limited, interactive searches and filter can be applied to the data and the Quicktime animation and colour coded; bottom row: pedestrian view and front/side/top can also be seen with a browser plug-in. (This web application was implemented by the au thor of this thesis). This thesis has its focus on shapes and uses digital media extensively. A consistent presenta tion of three dimensional and related two dimensional shapes is anticipated. Because a full media library would be beyond the scope for a diploma thesis and visualisation is only a part of this project, just a conceptual media library is implemented at the moment that shows the different visualisation techniques in some examples. The review of visualisation technologies resulted in the following implementation: The safest way to present three dimensional shapes is “still images renderings”. Three dimen sional objects have been created in 3D modelling software packages and then rendered from predefined virtual camera positions. Beside of the main camera position, which all rendered objects have in common, an alternative camera position shows the shape from a “pedestrian perspective”. Further camera positions are the traditional front, side and top view. Most of the objects with curvature have been modelled using a “NURBS tool set”, while most poly gonal objects have been modelled with a “Polygon tool set”. Figure 84: colour coding; top row: blue typology items; bot tom row: green catalogue item and red project item The objects are all rendered out in grey scale and colour tints are applied afterwards in a so called “compositing” application. This way the colour coding can be used to guide the user through the different parts of the ontology. Typology classes and items are tinted blue, cata logue classes and items green and project classes and items red. Also within the compositing software some overlays with transparent effects have been created. This results in combined
“Building Shape Ontology” by Philipp Jurewicz 63 8. Digital Media
outline and shaded images which are easier to read then pure shaded renderings. The media is not identified by a descriptive file name but rather by an abstract id called “frame number”. The term frame derives from common usage within 3d modelling and compositing software. The frame number is assigned to a data property in the ontology for all items that can present media. For further orientation frame ranges are stored in comment fields of main branch items. Media is referenced in the ontology with relative path URLs. The visual work flow can be described as follow: In a 3D computer graphics application (like Alias Maya or Autodesk 3D Studio) the model is created within a predefined bounding box. The desired perspective can be previewed by starting with a template frame that references the cameras which will also be used in the final renderings. All “history dependent” informa tion can be left intact (e.g. Curve-NURBS dependencies). If NURBS have been used a con verted poly-faces version can be stored as a hidden node too and exported into the “obj” file format that can be interpreted by the 3D JavaView applet. The rigged model is stored with a file name like “frames\frame1234_smart..mb”. A stripped down version with no referenced cameras, help geometry and modelling history should be saved in like “frames\frame1234..mb”. This reduced files are grouped in so called “shelves”. Essentially they just represent groups of up to 200 single frames that are grouped in manageable entities. For instance the shelf “grid\shelf1400_surface.mb” contains frames with numbers between 1400 and 1600 for the typology “surface”. The file “grid\grid..mb” stacks the shelves to one big grid, so all data is now present in one file. The concept behind the renderings is based on an animated camera rig that moves with each time frame to the next model frame. The ren derings from the “grid\grid.mb” file result in the shaded images. The renderings from the “grid\grid_frontwire.mb” and “grid\grid_backwire.mb” result in the line art. These rendered images are imported in a compositing software (like Autodesk combustion or Adobe After Effects) and are layered above each other. Different compositions result in print quality black and white models and tinted web content and thumbnails. Because complex shapes or subtle difference are not always evident from predefined camera perspective the author implemented a possibility to add interactive 3D models to the web ap plication. At the time of development the following end user products have been reviewed in their versions of 2005: • QuicktimeVR – drawback: the inspect mode of QuicktimeVR is essentially just a se quence of still images. This requires many still renderings (starting with something like 64) and offers only very limited user interaction.
“Building Shape Ontology” by Philipp Jurewicz 64 8. Digital Media
• Macromedia Shockwave 3D – drawback: the technology seems not to be accepted enough by tool vendors. • Java1 based VRML applets – drawback: VRML is an old standard which has some design flaws. Many Java1 based viewing applets only implement a part of the VRML specification which often collides with the data exported from 3D modelling soft ware. • VRML plug-ins: At the time of writing not a single VRML plug-in seemed to be backed by active development and some were very unstable. Many plug-in vendors have proprietary licenses models. X3D as a successor to VRML was not mature yet. • Wolfram Mathematica viewer – drawback: objects that are not in native Mathemat ica format are hard to import. • Dassault 3D XML viewer: In its first version this plug-in only works with Microsoft Internet Explorer. This option should be monitored in the future as it is the only viewer that can handle NURBS geometry and has intuitive access to a data tree for an end user. • Internal archistructura Java3D viewer: This viewer was developed concurrently to this thesis in a different thesis project. An integration of this two archistructura pro jects is anticipated in future development. • JavaView applet: This viewer is the final choice for the web application. It is small, written in Java1 (therefore no plug-in installation is necessary on Windows operation systems). It allows rotation, pan and zoom with the mouse and a reset to a initial camera position. It natively understands the (Polygonal-)OBJ file format which is an export option in all major 3D modelling applications. A custom file format can be used if further visual decoration is anticipated. The project is developed in an aca demic context and licenses for the optional stand alone editor are free for other aca demic projects. (see Fig. 85) Figure 85: Screenshot of the JavaView applet in the web application
“Building Shape Ontology” by Philipp Jurewicz 65 Summary Summary 1. Terminology Even though this is a paper about building shape it uses terms from contemporary know ledge base/ontology research: Item is used to describe an object of interest and a property is a link or reference between two items. A class is a set of items with a special characteristic in common. Classes are often organised in hierarchies/taxonomies. In computer science an on tology is defined as: A body of formally represented knowledge is based on a conceptualization: the ob jects, concepts, and other entities that are assumed to exist in some area of in terest and the relationships that hold among them (Genesereth & Nilsson, 1987) . A conceptualization is an abstract, simplified view of the world that we wish to repres ent for some purpose. [...] An ontology is an explicit specification of a conceptual ization.[Gruber 1993]. (see also Chapter 7.2. for detailed information about the term ontology) The terms classification and concept are used according to their broad meaning. The terms typology (shape), catalogue (shape) and project shape have a special meaning in this thesis and will be defined below. 2. Background to this Project Some existing approaches to building shape have been reviewed and they function as key re sources for the newly introduced meta classification. The “Institut für Leichte Flächentragwerke Stuttgart” (IL) published a very broad definition of shape/form which can be seen as a descriptive approach. It emphasises more on the characteristics of form rather then geometric definition. [Otto 1988] The Lightweight Structures Research Unit UNSW Sydney (LSRU) builds upon IL classification and applies it to the domain of buildings. The LSRU developed a mne monic code which describes shape with a specialised vocabulary and grammar. The SDA shape database table is a selection of some possible mnemonic code variations [Sedlak 2003 Online], [Loh 1990], [Cox 1996]. Surface definitions have been found from a designer point of view in [Joedicke 1962], from a graphical perspective in [Gheorghiu 1978] and as geometry in [wolfram.com Online 2005].
“Building Shape Ontology” by Philipp Jurewicz 66 Summary
Information about polyhedral solids comes from [Critchlow 1969], [wolfram.com Online 2005] and [Emde 1977]. The Internet was the main source for mathematical information, especially [wolfram.com Online 2005] and [maths.org Online 2005] 3. Classification of Building Shape This chapter describes the core concept of the thesis: A (shape) typology is a well defined, consistent and closed set of data that is organized by hierarchical relations and data graphs. Each typology focus on one methodology. A catalogue is a collection of possible idealised building shapes focusing on a specific aspects. Catalogues serve a purpose. The internal classes, items and properties of catalogues have a layout for a specific task like the research of lightweight structures or timber construction. A project shape is the visual representation of a building. If necessary it can be split up into elements, components, units, aggregates and composites. The shape ontology is the specification how typology shapes, catalogue shapes and project shapes are connected and what rules they must be committed to, to work well with each oth er. Some of this connection rules state: Typology shapes can and should refer to each other even between different typologies. Catalogue shapes refer to typology shapes that define them in a precious way with special properties/links. Project shapes should link to one or more cata logue shapes but have also the freedom to refer directly to typology shapes is appropriate. 4. Shape Typologies This chapter is a overview how typologies are organized. The following typologies are imple mented. • Arrangement describes how shapes related to each other or themselves in axes, car dinality, spacing, orientation and symmetry. • Proportion defines the special usage of “one”, “two” and “three dimensional”. • Surface follows the approach of [Otto 1988] in regards to curvature, corner, edge surface point and undulation.
“Building Shape Ontology” by Philipp Jurewicz 67 Summary
• Truncation descries subtraction of parts of volumes. • Geometry 2D defines angles, curves and polygons. • Geometry 3D is split up into three branches: One follows the definitions of three dimensional objects as solids, the other one as surfaces. They are ac companied by a small spatial curve branch. 5. Shape Catalogues The reference implementation of SDA shape catalogue, which derives from the LSRU key resources is described in detail. Some possible future catalogues are also outlined: Ground plan, truncation, membranes, and building profiles. 6. Projects Test Cases Some diagrams show how project shapes are connected to catalogue and typology shapes and which other project shapes can be inferred as “relative similar”. The ex amples are: Japanese Pavilion Expo Hannover, Multihalle Mannheim, Ufa Cinema Dresden 7. Digital Data Concepts A brief introduction into the computer science part of this thesis is given. Pros and cons of tables, hierarchies and data graphs are discussed. A high level introduction to ontology research and the semantic web vision is followed by some aspects how this architecture centric shape classification can benefit from them. 8. Digital Media The usage of three dimensional models and renderings is described. The colour cod ing concept for the web application is outlined. The chapter closes with a technical review of different 3D viewing techniques for browsers.
“Building Shape Ontology” by Philipp Jurewicz 68 Conclusion Conclusion Outcome
Existing research on shape was reviewed and connection points between different ap proaches were identified. As a conclusion of the review step it became obvious that an at tempt to unify the different classifications would be hard to achieve with traditional data representation. The concept of an „ontology“ was applied on abstract building shape know ledge. Organisation - The principal outcome of this thesis is a conceptual “building shape ontology“ describing building shape in a manner which is human readable and logically or ganised. By using semantic mark up it starts to become “understandable“ for knowledge-base software. Utilising current technology standards it can be imported directly into other onto logies or it can be transformed into custom data formats. Visualisation - A collection of two and three dimensional models and renderings of shapes accompanies the text-based shape-ontology. Spatial models of a shape can be altered, morph ed or viewed from another virtual camera perspective to emphasise different aspects of the model. The three dimensional models serve as a conceptual uniform shape library and a fur ther integration into 3D visualising projects is possible. The three dimensional models are used for the renderings. A set of images is bundled with the building shape ontology to assist a consistent visual experience. Presentation - The Internet changes the way we „navigate“ through data. The Hyperlink can change the context of the information with one mouse click and is well understood among an expert and lay user base. The developed web application can read and process the stand ard conforming files and present them to users within a browser in a customised way which is appropriate for this very visual content. This eases access, peer review and publication of the shape ontology, as users don't need to know how to handle specialised software. The web application (presentation) combines the shape ontology (organisation) with the 3D mod els (visualisation) by using multi media possibilities of the Internet. While print publications have limited paper space, a web application can have many sub pages without disrupting the whole presentation. Multiple images and 3D applets on a per-item-base allow information depth where necessary, while the default views allows homogeneous orientation and naviga tion. The initial intended audience for the web application are architecture students who seek for information on shape to enhance their designs.
“Building Shape Ontology” by Philipp Jurewicz 69 Conclusion
Conclusions The integrative approach introduced in this thesis enables us to reuse valuable resources without breaking up their consistency. A significant amount of computer science research is required and seems to open up a promising interdisciplinary field. Organisation - The move towards a data graph / ontology model was not anticipated at the beginning of the project but is used to solve the right problem with the right tools in a sus tainable way. In the meantime some other archistructura projects are picking up ontology concepts and the Protégé software. The aim to integrate the shape ontology into archistruc tura in a future step should be possible to achieve. The shape ontology uses a lot of defini tions and concepts from the SDA tool set. All SDA building projects are imported in an experimental sub class into the shape ontology and can be used within Protégé. They also ap pear in the web application. The editorial work to tag all of the more then four hundred SDA projects is still to be done. The aim to connect with the SDA data is achieved but tighter dy namic integration would require changes to the SDA itself. Visualisation - The challenging part of the media library is to keep the high amount of data connected and generation automated. The move towards a naming convention based on frame numbers allows the usage of video editing tools for efficient batch processing. On the downside this increases the complexity of the graphics work flow but should show benefits when the library grows. An other experience is that some shapes that are easy to sketch free hand are hard to reproduce in a three dimensional computer model. This slows down the creation of models and the anticipated aim to have an “all inclusive” media library had to be adjusted to a “conceptual” one. The over 300 three dimensional models and over 200 two di mensional figures should demonstrate the potential. Presentation - The web application can present the ontology and the connected media, so the primary aim is achieved. The programming model would allow further enhancements and more interactivity (cf. “further development” below), but the current status is a read-only im plementation. On the upside this makes it possible to created off-line versions of the content (excluding Java-Applets) so it can be easier distributed on CD-ROMs or published on web servers with less sophisticated technology infrastructure. Further development should include: Organisation – The consistent mapping of different shape classifications proved to be tedi ous and needs further attention. By adding more real world building projects the typologies could be further fine tuned. Shapes of internal spaces could be integrated. New shape cata
“Building Shape Ontology” by Philipp Jurewicz 70 Conclusion
logues could cover topics like “Membrane”, “Plan View”, “Cross Section”, “Truncation”, “Social Profiles”, etc. . Further shape typologies such as “Super formula”, “NURBS” and “Subdivision Surfaces” should be evaluated. The possibilities of ontologies and semantic web go beyond the implemented state and could further be researched and applied. Visualisation – The gaps in the media library could further be filled with more renderings an models. Adding of “structure emphasised visualisation” would integrate the shape ontology tighter into [archistructura Online 2005] Presentation - The user experience of the web application could be improved by additional “perspectives” like dynamic taxonomy trees (similar to the one inside of Protégé), specialised search queries and full text search capabilities. The integration of switches and filters could enable different users to customise the web application to their needs like: research with fo cus on one catalogue, investigation of interconnection of different typologies and catalogues or building project exploration for students with design studio assignments. Further research could use the building shape ontology introduced in this thesis as a base for a broader architectural shape ontology. This should be reintroduced into the context with other main aspects of buildings like structures, construction, material and application as in tended by the archistructura research project. Personal Conclusions: On a personal base I can conclude that this project was a good cross section of many of my academic and off-academic activities. This thesis was partly written at the UNSW in Sydney. The accompanying research paper publication [Jurewicz & Sedlak 2005] (see Appendix F) and the presentation at the IASS con ference in Warsaw was a great experience and gave me a glimpse what a future academic path for myself could be. Web development and web design was often a financial life saver during my summer breaks, but evolved towards a general interest and the gained expertise made the “web design” of this thesis much easier, so I could focus on the programming and organisation part. Setting up abstract frameworks that help collected data to come alive was part of my casual staff projects at two universities as well as to a smaller degree in the IT-consultant jobs I had dur ing my student years. The production pipeline of three dimensional modelling, morphing, rigging, rendering and compositing was always of great interest to me, and the visualisation of the building shape
“Building Shape Ontology” by Philipp Jurewicz 71 Conclusion
ontology allowed me to go in a much more fine grained detail then hectic student competi tion renderings do. A lot of interesting shapes require interesting structure, construction and material, which connects this thesis to my former work at the “Tragwerkslehre”-Institute. As architecture students we have been taught to see building as a whole and each investigation of a project shape was hopefully a sub conscious investigation of a lot more. At the end it deals with exciting shapes that are often part of exciting architecture.
“Building Shape Ontology” by Philipp Jurewicz 72 Conclusion
Acknowledgement I especially like to thank my supervisor Vinzenz Sedlak, who invested a lot of time in review and consulting and helped out on many administrative hurdles, well beyond the common su pervising level. The access to the LSRU archives and his personal library serve as the founda tion of this thesis. I also like to thank the Ausseninstitute of the Vienna University of Technology who suppor ted my overseas stay with a scholarship, so the financial burden was eased. Wolfgang Winters and Vinzenz Sedlaks support on this was very much appreciated by me. Wolfgang Winters feedback and his view of my project in the scope of architecture as an in tegrated whole helped me to position the thesis in its architectural context. I want to acknowledge the support from Wolfgang Winter, Margit Pfeiffer-Rudy and Stefan Jaksch from the Institute of Architectural Sciences, Structural Design and Timber Engineer ing who created the academic environment which made a theoretical architecture thesis like this possible. The thesis benefited well from the feedback sessions at the institute. Graham Bell from the Faculty of the Built Environment, University of New South Wales, supported me on administrative tasks and hosted me at his faculty and his academic feedback was always insightful. I also like to acknowledge the consulting and feedback from my colleagues Pit Kuffer and Jota Panotopoulo.
“Building Shape Ontology” by Philipp Jurewicz 73 References References [Andreoli & Forty 2004] Elisabetta Andreoli, Adrian Forty "Brazil's Modern Architecture", London, Phaidon Press, 2004 [archistructura Online 2005] "archistructura" Institute of Architectural Sciences, Structural Design and Timber Engineering, Vienna University of Technology, May 2005 [Online] http://www.archistructura.net [Berners-Lee 2004] Tim Berners-Lee interviewed by Mark Frauenfelder "Sir Tim Berners- Lee: He Created the Web. Now He's Working on Internet 2" , MIT Technology Review, Oc tober 2004 [Berners-Lee 2005] Tim Berners-Lee interviewed by Andrew Updegrove "The Semantic Web: An Interview with Tim Berners-Lee" , Consortium Standards Bulletin, June 2005 [Cox 1996] S. Cox "SDA Typology Compendium (unpublished)" , Lightweight Structures Research Unit ,University of New South Wales, 1996 [Critchlow 1969] Keith Critchlow "Order in Space", London, Thames and Hudson, 1969 [Daconta, Obrst & Smith 2003] Michael C. Daconta, Leo J. Obrst & Kevin T. Smith "The Semantic Web, Chapter 7 and 8", Indianapolis, Wiley, 2003 [Emde 1977] Helmut Emde "Geometrie der Knoten-Stab-Tragwerke", Strukturforschung szentrum e.V., Würzburg, 1977 [File Maker 2005] "File Maker" , May 2005 [Online] http://www.filemaker.com [Gheorghiu 1978] Adrian Gheorghiu, Virgil Dragomir "Geometry of Structural Forms", Barking, Applied Science Publishers Ltd., 1978 [Gruber 1993] Tom R Gruber "What is an Ontology?" Stanford Knowledge Systems, AI Laboratory, 1993 [Online] [Horridge 2004] Matthew Horridge "Protégé OWL Tutorial" Collaborative Open Ontology Development Environment (CO-ODE), August 2004 [Online] http://www.co-ode.org/re sources/tutorials/ProtegeOWLTutorial.pdf [hpl.hp.com Online 2005] "Jena Semantic Web Framework" Hewlett Packard Labs, May 2005 [Online] http://www.hpl.hp.com/semweb/jena.htm
“Building Shape Ontology” by Philipp Jurewicz 74 References
[Joedicke 1962] Jürgen Joedicke, Walter Bauersfeld, Herbert Kupfer "Schalenbau -- Doku mente der modernen Architektur, Band 2", Stuttgart, Karl Krämer Verlag, 1962 [Joedicke 1977] Jürgen Joedicke, Heinz Direwanger, E. Geisler & V. Magnago-Lampugnani "Zur Gestaltung weitgespannter Flächentragwerke - Das CEMAG-Verfahren als Entwurf shilfe (research report)" , Special Task Area 64 ,TU-Stuttgart, 1977 [Jurewicz & Sedlak 2005] Philipp Jurewicz & Vinzenz Sedlak "Building Shape Online" in Lightweight Structures In Civil Engineering, IASSWarsaw , 2005, p314-318 [Loh 1990] Seok Kuan Loh "Vocabulary of Shape and Structure Type (research report)" LSRU, Faculty of Architecture ,University of New South Wales, 1990 [Martins 1996] Luis Câncio Martins"Morphologie der gekrümmten Flächentragwerke", Ei dgenössische Technische Hochschule (Zürich), Birkhäuser,Zürich, 1996 [maths.org Online 2005] "Connecting Mathematics" University of Cambridge and Partners, May 2005 [Online] http://thesaurus.maths.org [Merriam-Webster Online 2005] "Merriam-Webster Online" Merriam-Webster, Incorpor ated, March 2005 [Online] http://www.m-w.com [Otto 1988] Frei Otto "IL 22 Form", Stuttgart, Karl Krämer Verlag, 1988 [Otto et al 1979] Frei Otto et al "IL 21 Form - Forc- Mass 1, Basics", Stuttgart, Karl Krämer Verlag, 1979 [peda.com Online 2005] "Poly" Pedagoguery Software Inc., May [Online] http://www.ped a.com/poly/ [Pfeiffer-Rudy 2005] Margit Pfeiffer-Rudy "Semantic Differentials Analysis in Architectural Education" in ED-MEDIA 2005: World Conference on Educational Multimedia, Hyperme dia & Telecommunications, Montréal , 2005, [Sedlak 1986] Vinzenz Sedlak "The Morphology of Structure" in Proceedings LSA'86 First International Conference on Lightweight Structures in Architecture, Sydney , 1986, 1164- 1187 [Sedlak 1996] Vinzenz Sedlak "Structures Design Aid Database", Lightweight Structures Re search Unit 1996-2001, Faculty of the Built Environment 2001-2005, Sydney, 1996-2005 [Sedlak 1997] Vinzenz Sedlak "A Computer-Aided Conceptual Structural Design Aid" in
“Building Shape Ontology” by Philipp Jurewicz 75 References
Proc. 1997 IASS Symposium, 9-14 Nov 1997, Singapore , 1997, 745-754 [Sedlak 2003 Online] Vinzenz Sedlak "The Morphology of Structures (Updated Version)" University of New South Wales, 2003 [Online] http://emuweb.fbe.unsw.edu.au:8080/ [stanford.edu Online 2005] "Protégé" Stanford Medical Informatics, Stanford University, May 2005 [Online] http://stanford.protege.edu [w3 consortium Online 2004] " Web Ontology Language (OWL)" World WideWeb Consor tium, 2004 [Online] http://www.w3.org/2004/OWL/ [w3 consortium Online 2005] "Various Internet Standards" World WideWeb Consortium, May 2005 [Online] http://www.w3.org/2004/OWL/ [Wehdorn-Roithmayr 2003] Robert Wehdorn-Roithmayr "Formfinder concept for a soft ware-tool to assist architects in the preliminary design of form-active structures" Dissertation at TU Wien 2003 [wolfram.com Online 2005] Eric W. Weisstein "Mathworld -- A Wolfram Web Resource" , May 2005 [Online] http://mathworld.wolfram.com Image References • Fig. 4, 5, 6 - [Otto 1988] • Fig. 7 - [Sedlak 1986] • Fig. 8, 79 - [Loh 1990] • Fig. 9 - [Critchlow 1969] • Fig. 11 - Wikipedia (http://en.wikipedia.org/wiki/Soap_bubble) • Fig. 13, 14, 15, 16 - Michael A. Stecker (http://mstecker.com) • Fig. 17 - Paul Meurs from [Andreoli & Forty 2004]; annotation by author • Fig. 30 - by author, containing icons from a font by Listemageren • Fig. 47 - [wolfram.com Online 2005] All other figures, images, renderings and illustration are created by the author.
“Building Shape Ontology” by Philipp Jurewicz 76 Appendix Appendix 1. Appendix A - Typologies
“Building Shape Ontology” by Philipp Jurewicz 77 2. Appendix B - Catalogues
2. Appendix B - Catalogues The SDA building shape catalogue has one main branch level and has 269 items The media is based on the original artwork from the SDA database [Sedlak 1996]. Approxim ately a quarter of the models have been reproduced in three dimensions for this thesis. Please see the accompanying CD-ROM for the full data.
“Building Shape Ontology” by Philipp Jurewicz 78 3. Appendix C - Web Application
3. Appendix C - Web Application The web application can be accessed in three different ways: There is a static version of it on the CD-ROM which present all data expect the JavaView 3D interactive items. You can find the starting point by following the main HTML navigation of the CD-ROM. The ready-to-deploy web application in the folder \webapps\shape31 can be dropped in any recent java-based web server (like the open source Apache Tomcat) and it will reflect your changes to the Ontology files (restart required) The project folder \eclipse_project\shape31 can be mounted in Eclipse 3.1 (+ Web Tools) and the source code and unit tests can be accessed. The current Java dependencies are: Jena 2.2, Arq 0.9.6, Apache Commons Configuration 1.1, Apache Commons Lang 2.1, Spring Framework 1.2.2 and Apache Xerces 2.7.0. They are open source, the license allow redistri bution and they are all included. (see also Appendix D). Updated online versions might be available please contact me to get informations about URLs [email protected] The application is ready for internationalisation and the “developer bookmarks” (see screen shot on the next page) give access to the experimental German version. The multilingual content can be entered in Protégé because the web application respect the “rdf:label” stand ard for different languages. English serves as the fall back language. The dynamic user inter face parts can be internationalised by editing the Java standard language locale in the class path. An English and a German locale is already present. The dark grey colour theme was inspired by high end computer compositing software and puts visual information like renderings and the orientation colours (blue, green and red) in focus.
“Building Shape Ontology” by Philipp Jurewicz 79 3. Appendix C - Web Application
The portal page give quick access to interesting items deep in the ontology
Additional technical bookmarks are available but hidden
Navigation links to the start, portal and credits page are on the right
The main branches of the ontology can be quickly accessed through the top navigation. The top contains the main branches on typologies (blue), cata logues (green) and projects (red). The second row shows the next level of a selected main branch. (In this case typologies)
The detail are of the currently selected items, shows a big image where avail able. There are also some tabs which stay selected even when one browse to an other subjects.
“Building Shape Ontology” by Philipp Jurewicz 80 3. Appendix C - Web Application
A traditional hierarchy
This class has four super classes and they are all visible in the navigation. This is not possible in traditional tree structures but the data graphs used by the shape ontology make it possible.
“Building Shape Ontology” by Philipp Jurewicz 81 3. Appendix C - Web Application
The fact that an item has more than one superclass in different main branches is also indicated by the fact that more then on is selected in the top navigation indicated by the bar.
The left column indicates all references from this project shape to different catalogue shapes (green) and typology shapes (blue). The right column shows an experimental feature, that tries to infer relative similar project shapes within the we application. The implemented algorithm is not very sophisticated and is mainly present to show the potential for fur ther development and automated reasoning.
“Building Shape Ontology” by Philipp Jurewicz 82 3. Appendix C - Web Application
Some typology and catalogue items have additional renderings and some project shapes have additional photographs of buildings attached to them. You can access them by selecting the “more images” tab. The tab will stay selected even when an new item is clicked.
Some typology and catalogue shapes have interactive three dimensional models attached to them. You can access them by selecting the “3D Java” tab. You can interact with the model by orbiting, scaling and translating it with the mouse and the keyboard. Some items have more then one model with different colour and shading attached to them symbolised by the gener ic dome segment icons.
“Building Shape Ontology” by Philipp Jurewicz 83 4. Appendix D - Java Programming
4. Appendix D - Java Programming The Java programming language [D1] has a strong user base within the semantic web re search community. The two main software products used in this thesis are open source Java projects that are leading innovation within the applied ontology field. The choice to uses Java for the implementation of the shape browser web application was therefore consequent. Also Java application server infrastructure is available at both universities so the deployment pro cess should be simplified. Protégé 3.1 [D2] Protégé is an open source project lead by Stanford University Medical Informatics with a sustainable funding. It has an extensible plug-in API and many academic and some commercial institutions are writing specialised plug-ins. One of the main plug- ins is the OWL plug-in [D3] which is used in this thesis. European Union research initiatives are also supporting this software and the University of Manchester is a ma jor contributor [D4]. The OWL plug-in uses the Jena API [D5] internally to store OWL ontologies. Jena API [D5] The Jena API is an open source project lead by Hewlett Packard Labs semantic web research group [D6]. The ARQ sub project is also an early adopter implementation of the upcoming semantic web query language SPARQL [D7]. SPARQL is used to some extend by the shape ontology web application. Apache Tomcat [D8] Tomcat is an open source Java web application server from the Apache Software Foundation [D8]. It is the reference implementation of new official Java web applic ation technology and is widely backed by commercial vendors and open source com munity. The shape ontology application runs with a Tomcat 5.5 on Java 5. Spring framework [D9] The open source Spring framework [D9] was used as a foundation for the shape on tology web application. The decision in favour of Spring as opposed to Cocoon framework [D10] was based on the fact that data graphs and RDF data require a dif ferent processing model then a traditional XML pipeline. At the time of develop
“Building Shape Ontology” by Philipp Jurewicz 84 4. Appendix D - Java Programming
ment no RDFS/OWL models were integrated in the common web frameworks. The Spring framework is well organised and agile towards extensions. The implementa tion of a custom OWL model based on Jena appeared easier in Spring then in the XML centric Cocoon. At the time of this thesis Struts [D11] was still the dominant Java web framework but it was based on a ridged software architecture modelled for big commercial web application and was not as modular and transparent as the Spring framework which suits better the relatively small shape ontology web applica tion. Eclipse IDE [D12] The integrated development environment (IDE) used throughout the web develop ment was the open source Eclipse project [D12].Also the text editor jEdit [D13] was used for XML and JSP/HTML editing.
The Java related structure on the CD-ROM: • \webapp\shape31 is a deployable Java Web Applications • \eclipse_project\shape31 is a Eclipse Java Project
Appendix References • [D1] http://java.sun.com • [D2] http://protege.stanford.edu • [D3] http://protege.stanford.edu/plugins/owl/ • [D4] http://www.co-ode.org • [D5] http://jena.sourceforge.net • [D6] http://hpl.hp.com/semweb/ • [D7] http://www.w3.org/TR/rdf-sparql-query/ • [D8] http://tomcat.apache.org/
“Building Shape Ontology” by Philipp Jurewicz 85 4. Appendix D - Java Programming
• [D9] http://www.springframework.org/ • [D10] http://cocoon.apache.org • [D11] http://struts.apache.org/ • [D12] http//eclipse.org • [D13] http://www.jedit.org
5. Appendix E - Data Format OWL The shape ontology was created in the software editor Protégé 3.1 [stanford.edu Online 2005]. with the Web Ontology Language (OWL) plug-in. The data is stored in the OWL file format in a single file. The CD-ROM contains the following files: • \webapps\shape31\ontology\shape.owl the OWL data file • \webapps\shape31\ontology\shape.pprj the Protégé project file with meta info. • \webapps\shape31\res a directory structure with all media resources
OWL is a w3 consortium standard [w3 consortium Online 2005]. It build upon established w3 standards like the Resource Description Framework (RDF) and RDF-Schema. The shape ontology is saved in the RDF-XML file encoding with UTF-8 character encoding. XML transformation tools (XSLT and XQuery) and RDF-Query language tools (SPARQL, RDQL) can be used to transform the data in custom formats. When processed through the Hewlett Packard Labs Jena API [hpl.hp.com Online 2005] the data can also be accessed by the Java programming language.
“Building Shape Ontology” by Philipp Jurewicz 86 6. Appendix F - Publication
6. Appendix F - Publication
“Building Shape Ontology” by Philipp Jurewicz 87