Supporting Tools for Early Stages of Architectural Design Ernesto Bueno and Benamy Turkienicz

international journal of architectural computing issue 4, volume 12 495 Supporting Tools for Early Stages of Architectural Design Ernesto Bueno and Benamy Turkienicz

In architectural design, pencil and paper remain the most frequently used media to create freehand drawings to support early design stages. Digital tools conventionally used by architects lack appropriate functionalities and do not offer friendly interfaces for the early stages of architectural design.These are the bad news.The good news are twofold: a) hardware already available can help freehand designers to digitally express their first ideas; and b) functionality principles present in experimental software combined with appropriate hardware could successfully provide a friendly and intuitive human-computer interaction in the early stages of architectural design.This paper takes special attention to the way architects interact with computers, how input devices constrain possible interactions and how functionalities can be explored through these interactions.The article summarizes basic principles to be considered in the development of an all-in-one software and create a scenario whereby these principles are simulated on a hypothetical software to be used during the early stages of architectural design.

496 1. INTRODUCTION As a design activity, drawing is a visual and mental transaction, a conversation that the designer establishes with him/herself.The ideation process is shaped by the reflexive cycle: sketch, inspect, revise [1]. Design improvements are achieved from the designer’s sequence of actions resulting in transformations of the representation [2].To make progress through the reflexive cycle, designers must have the ability to transform implicit knowledge into representational structures fast enough, so that new changes and amendments reflect the interpretation of what was revised, creating continuity between mind and the drawing in process [3]. To establish this connection between mind and drawing, designers make use of their visual intelligence [4] as to associate different represented shapes [5].Visual intelligence is one of the main types of human intelligence connected with major parts of the brain [6]. It is specially developed in architects, who exploit this potential through visual training during their education and professional experience [4].The continuous training allows architects to depict emergent shapes and patterns which are fundamental for the intermittent reinterpretation of a design idea. In architectural design, visual emergence set the environment for shape interpretations of architectural elements. For example, in Figure 1, the designer recognizes, in the overlapping of two rectangles, an emergent rectangular shape.This can be interpreted as a shadowed area at the overlapping of rectangular volumes (Figure 1, Left), or as a void, framed by two L-shaped volumes (Figure 1, Right).These emergent shapes can be interpreted as architectural elements with different spatial properties existing in a (not yet represented) third dimension, as illustrated in Figure 2.The first interpretation would define an internal space without direct sunlight (Figure 3, Left), while the second interpretation would define internal spaces with direct sunlight (Figure 3, Right).

Figure 1: Manual recognition of emergent shapes on conceptual architectural sketches in floor plan.

Figure 2: Sketches of sections illustrating architectural consequences of different interpretations.

Supporting Tools for Early Stages of Architectural Design 497 Figure 3: Perspectives showing 3D models of different sketch interpretations.

The sequence of drawings acts as a registry of the process of reasoning that designers build from inspection and revision of previous drawings, which demarcates the thresholds from one representation to another.The “re- representation”, or sequence of representations produced through over sketching, can result in proposals of unexpected novelty and diversity [2]. By inspecting the sequence of drawings, designers can reinterpret relations and features which were not initially clear, suggesting ways of revising original ideas: through re-representation, the new is built upon the existent [2]. While focusing on thinking and representing design solutions within the reflexive cycle, designers are not used to explicate the knowledge and abilities applied to design, nor how these knowledge and abilities are used [7].Architectural designers implicitly coordinate a series of personal methods based on the experience of constructive perception [8], an ability of the mind that allows trained designers to coordinate cognitive actions of reorganization (through visual emergence) and conceptual generation (by re-representation). Incorporating this specific ability, designers improve personal methods whereby they achieve design solutions and, through experience, get faster and better connected with their intuitive world [8]. To shed light over some basic requirements that digital technologies could offer to architects at early design stages, this article is divided in six sections. Section 2, describe existing representational methodologies in the early stage design. Section 3 demonstrates how designers interact with software and hardware technologies in architectural design and some of the difficulties architects suffer in dealing with current tools and techniques. In section 4, the state-of-the-art studies of experimental technologies supporting interactions and functionalities are reviewed. Section 5 describe a scenario of use of a hypothetical software for early stages of architectural design. In section 6, the basic principles for development of such an application are briefly suggested.

2. DESIGN REPRESENTATIONS IN THE ARCHITECTURAL DESIGN PROCESS The most representative workflow of an architect begins with contextual data collection, formulation of the design problem and developing sequences of sketches that progressively address formulated problems [2]. In the early stages, design problems are so ambiguous that freehand drawings are

498 Ernesto Bueno and Benamy Turkienicz preferred [9] when designers take advantage of their ability to reorganize emerging shapes [10], coordinating them in conceptual generation [8] of re- representations [2], and defining the architectural team. In this phase, sketch remains the most appropriate representation to address design problems [11, 12, 13], followed by more accurate technical drawings, using CAD [11]. Activities in the early architectural design stages typically happen through sketches using pencil and paper [11, 14]. Ideas shaped in paper externalize, through fuzzy or vague representations, the designer’s intentions in the approach of ill-defined problems. In advanced stages, designs are digitally represented with technical drawings [15], using CAD tools, mainly Autodesk AutoCAD; 3D models, typically using Trimble SkekcthUp [16]; and performance simulations, using software such as Autodesk Ecotect [17]. Performance simulation software includes resources that temporarily change the appearance of the model in different ways, according to the simulated phenomena: airflow is represented by drawing vector fields; lighting simulations involve the discretization of models by sampling and coloring polygon meshes, according to the incident light. CAD, 3D modeling and simulation software, offer features targeted for more accurate representations than those produced with freehand drawings.To use the digital media, it is necessary to transfer architectural design ideas sketched on paper to computers and specify the information, making explicit issues that, in sketches, were diffusely or implicitly addressed [18]. Designers transfer design ideas from paper to digital environments by scanning and redrawing in CAD, overlapping layers above bitmap images of the sketches; or creating new CAD drawings from scratch, based on observation and re-creation of features from the sketch [19].The transfer process involve interpretation, is time consuming [11] and inefficient [13]. The inefficiency of media transfer can be avoided, by eliminating the need to transfer. In other words, if all stages are developed in the digital environment [11] designers will employ freehand drawing techniques for the creation of early design sketches.The problem is that existing input devices such as styli [20] and the bitmap images generated with these hardware and aggregated software are not compatible with the requirements of vector drawings in CAD. There exists a trend, in architectural design, for using CAD tools in all design stages [11, 14].Aside from the underuse of styli in CAD, there are several limitations in CAD tools in comparison to freehand drawing.This trend is detrimental to the architectural project for reasons which will be explained as follows.

2.1. Drawbacks in the use of CAD tools in early stages of design 1. Additional cognitive load makes the design process inefficient: the connection between mind and CAD drawing through the mouse makes the initial design activities slow and inefficient, compared to

Supporting Tools for Early Stages of Architectural Design 499 the connection between mind and sketch through the pencil [13]. The pencil allows a continuous drawing process, even on ill-defined ideas.When stopping the process to follow CAD command protocols, designers increase their cognitive load [21] and take longer to define a design solution [11, 22]. 2. Communication gets disturbed: when the designer works without prior creation of hand drawings, the collaboration between designers and communication with the client (or teacher) are difficult, since the visual discourse based on graphic conventions is broken [14]. Conventions, such as the visual gestures of communicative sketches and architectural symbols present in prescriptive sketches, enrich communications of design ideas and avoid misinterpretations [23]. 3. The quality of the design diminishes:projects initiated in CAD are often evaluated as worse than projects initiated with freehand drawings, as registered by instructors of Architectural Design Studios [11, 14, 24]. Summing up, the use of CAD tools in the early design stages turn design into a slow and inefficient process, with design solutions lacking communicative qualities and worse than those initiated with freehand sketches [11, 14, 24].To support the continuity between design stages it is necessary that, in the early stages, representations are created with digital tools supporting freehand sketching, similar to paper and pencil [25]. Conceptual ideas will be represented faster, closer to what the designer imagine and will offer a more adequate communication flow than current CAD and 3D modeling tools [25].

3. INTERACTION WITH INPUT DEVICES AND PERFORMANCE SIMULATIONS IN ARCHITECTURAL DESIGN Technologies supporting architectural design do not widely offer (to the end-user) digital tools for the most important activities in the early stages of the design process, especially freehand drawing [25]. Interaction with desktop and laptop computers remain, almost exclusively, based on mouse and keyboard input.This interaction suffer with limitations, starting with the design of the mouse.

3.1. Mouse interaction Affordance is a property in the interaction between the user and the device, based on the perception of the characteristics of the device [21].The mouse’s affordance is related to pointing and clicking buttons, as required for CAD drawing [26]. Examining the hand’s position above the mouse and the possible movements of the mouse in relation to the movements perceived by the user on the screen, it is possible to affirm that this device

500 Ernesto Bueno and Benamy Turkienicz does not offer a good relationship of perceived control of free pointer drag. Drag is the action required to create the strokes that form the sketch [27]. From its drag function’s point of view, the mouse is inappropriate for drawing sketches [28]. The mouse, located outside the visual field in which the relation cognition-representation is established, oblige users to make an extra effort of synchronization between the movement of the hand and the corresponding movement of the pointer on the screen, as two distinct agents, responding to different rules, acting in the same activity [26]. In the cycle: draw, inspect, revise, for each design iteration, two physical gestures are, at least, required: the user moves the mouse, inspects the consequent movement of the pointer, providing a feedback of the first movement, which informs motor adjustments in a second mouse movement, with which the edition is started.This interposition limits continuity between cognition and representation, which is a key factor for the development of the design through iterations [29].

3.2. Pen and multi-touch interaction Company et al. [13] demonstrated the qualities of interaction through stylus pen, with a comparative study between the aforementioned tools and traditional media.The study focused on the assessment of efficiency, according to the time spent on sketching, and usability, from the qualitative response from users. Sketching with pencil and paper was judged as more intuitive and faster than how CAD drawing was, especially between experienced designers. It was noted that pencils allow improvisations and imperfections and that are comfortable to the hand.The same work done with stylus on a tablet computer, was reported as advantageous for its similarity to traditional pencils, sharing the same affordance for writing and sketching, in addition of being fast, clean and easy to erase [13]. The adoption of tablet computers, in addition to promoting the use of styli, contributes to the familiarization of multi-touch gestures, generally used in text and image applications, but with principles of use common to associated design tasks, especially navigation (e.g., zoom and pan) and editing (e.g., moving, rotating, scaling). Hinckley et al. [30, 31], address the problem of developing a software for graphical annotations (diagrams and storyboards) that, exploring these technologies, offer an alternative bimanual interaction by combining pen and multi-touch simultaneously.This blend was inspired in the creative activities of bimanual work made with traditional media, combining tools such as pencils, rulers, scissors and manipulation of sheets of paper.The study has shown that, for users, pen and multi-touch are perceived as easy to use as traditional tools and media [31]. Considering the benefits of working in digital environments, such as data storage and portability, communication features, latter reproduction and edition and, most importantly, the

Supporting Tools for Early Stages of Architectural Design 501 possibility of direct transition between the early and advanced stages, supporting the appropriate CAD formats, Hinckley’s conclusions seem to constitute an important support for the use of digital media in the early stages of architectural design.

3.3. Model affordance from performance simulations In the decision making process at different design stages, the designer interacts with the representation in the construction of the design idea whereby the designer applies implicit knowledge to improve the design [2]. The designer´s knowledge related to the building performance under development is externalized through architectural drawings [32]. By using performance simulation software, the designer utilizes his/her visual intelligence to relate implicit knowledge with performance values represented in the simulation as to make informed decisions [33].When performance results are unfavorable, rethinking the design is required.The visualization of the impact of the simulated characteristics (e.g., the dimensions of the massing), help the designer to reshape the architectural form which, in turn, will update the simulation results [34].The relationship between simulation and design can be seen as the cyclical interaction between the designer and the simulation model, based on the perception of the characteristics simulated [33].The performance simulations emulate the architectural model affordances towards design improvements [21].As architectural affordances are better explored during the early stages of design, initial design decisions are likely to affect the building performance more intensely than at the intermediate and final design stages. Modifications to improve building performance, involve more specific and costly data in the intermediate and final design stages than in the early stages and it is more time-consuming.

3.4.Availability of performance simulation, pen and multi-touch technologies for architects Architects and the building industry will always be interested to perform simulations in the early stages of design, when design modifications are not as expensive as the intermediate and final design stages [35]. For this purpose,Autodesk introduced Ecotect for the analysis of the buildings environmental performance [36] and proposed Vasari to assist designers in the early stages of architectural design [17]. Paradoxically,Vasari was designed to work jointly with software to support advanced stages of design and construction (i.e., BIM). In order to grant its BIM compatibility, Vasari requires the addressing of specific building attributes [17].This automatically drives the designer attention away from the conceptual problems, breaking the mental workflow of the early design stages. Hardware for direct input such as multi-touch screens and styli, allowing digital freehand drawings, are commercially available for the general end-

502 Ernesto Bueno and Benamy Turkienicz user and widely used since the introduction of smartphones and tablet computers [37, 38, 41]. With the exception of Autodesk FormIt [42], available applications with pen and multi-touch interaction targeted to architects do not support multi-touch 3D modeling [43] and do not address an automatic transition from the early to the advanced stages of architectural design.With specific software out of the reach of architects, direct input devices are not seen nor experienced as design tools.There exists however, some experimental technology that can be used in the early design stages that have the potential to fulfil this gap as will be examined in the next section.

4. STATE-OF-THE-ART DIGITAL TOOLS FOR THE EARLY STAGES OF ARCHITECTURAL DESIGN The state of the art on digital tools which could potentially be used for the early stages of architectural design had been reviewed, classified and Table 1: Comparison of state-of-the- art experimental software main schematically synthetized in Table 1. In this table, the main features of features. experimental software are organized and compared.All compared digital

Application Drawing Drawing Reconstruct- Performance Interop- Reference Area input approach ion action simulation erability

Perspective High Company et al., 2003 [45] Engineering Pen Automatic N/A recognition (DXF)

Mouse & 2D vector Pranovich, 2004 [46] Architecture N/A N/A N/A keyboard drawing

Juchmes et al., 2005 [25] Architecture Pen 2D sketching Automatic N/A N/A

Architecture Pen & Medium Kallio, 2005 [29] 3D sketching N/A N/A & Design keyboard (VRML)

Perspective Masry & Lipson, 2005 [19] Engineering Pen Automatic Structural N/A recognition

Mouse & 3D sketch Medium Oh et al., 2006 [47] Architecture WIMP N/A keyboard extrusion (3D)

2D sketch Yu & Zhang, 2007 [18] Architecture Mouse WIMP N/A N/A extrusion

Pen & Dorsey et al., 2007 [44] Architecture 3D sketching N/A N/A Low (2D) keyboard

Elsen & Leclerq, 2008 [48] Architecture Pen 2D sketching N/A N/A N/A

High Naya et al., 2008 [49] Engineering Pen 3D sketching Gestural N/A (DXF)

Pen & multi- Lopes et al., 2011 [50] Visual Arts 3D sketching Gestural N/A High (3D) touch

Elsen et al., 2012 [51] Architecture Pen 2D sketching Automatic N/A N/A

Medium Kang et al., 2013 [43] Engineering Multi-touch 3D sketching Gestural N/A (macro)

Supporting Tools for Early Stages of Architectural Design 503 tools feature sketch acquisition and, with the exception of Kallio [29] and Dorsey et al. [44], all perform some kind of shape recognition. It can be observed that two digital tools [39, 47] base the user’s interaction on mouse and keyboard.Yu and Zhang [18] define the user’s interaction only with a pointer, for latter replace of the mouse with a pen. Most of tools define drawing interaction with the pen, but Kallio [29] and Dorsey et al. [44] rely on the keyboard to control the 3D positioning. Kang et al. [43] support the design solely with the fingers with multi-touch gestures, Lopes et al. [50] explore a multimodal, bimanual interaction [30, 31] combining pen and multi-touch, and Pranovich [46] adapts 2D vector drawing for the development of schematic architectural plans. Company et al. [45], and Masry and Lipson [19] implement a complex algorithm to recognize 3D shapes automatically from perspective sketches, while Juchmes et al. [25] and Elsen et al. [51] address the automatic reconstruction from floor plan sketches. Kallio [29] and Dorsey et al. [44] do not use solid geometry but 3D sketches, avoiding the implementation of reconstruction routines.The construction of solid geometry, proposed by Oh et al. [47], and Yu and Zhang [18], involve the extrusion of recognized polygons by interacting with WIMP interface resources (mainly buttons). Naya et al. [49], Lopes et al. [50] and Kang et al. [43] propose supporting gestures for the sketch reconstruction control. Except for Masry and Lipson [19], preliminary performance simulations of building design are not explored. Company et al. [45] and Naya et al. [49] offer high interoperability by using the DXF format, whereas Lopes et al. [50] offer high interoperability with other 3D formats. Kallio [29] provides interoperability through VRML files with generated data limited to 3D lines. Oh et al. [47] permit external performance simulation through exported models, while Dorsey et al. [44] allow the generation of perspective images, which cannot be used in subsequent design stages. All the functionality principles mentioned should be integrated in one single software for an appropriated support to early stages of architectural design. Each of these functionality principles have a specific role or attribute needed in software for the early stages of architectural design and are synthetically presented in Figure 4 and described as follows.

Figure 4: Principles of functionality needed in software for early stages of architectural design.

504 Ernesto Bueno and Benamy Turkienicz 4.1. Functionality principles Multimodal, bimanual interaction: Interaction modes, inspired in traditional bimanual work—with stylus pen and multi-touch screens—define three interaction modes: (i) Creation: drawing and annotating with a stylus [49]; (ii) Manipulation: navigating through the model with multi-touch gestures [42]; and (iii) Edition: modifying the model with simultaneous stylus and multi-touch inputs, composing bimanual gestures for editing and geometry transformations [30, 31, 50].When defining new gestures for input or control, consider typical architectural design manual tasks above other criteria based on precedent software. Sketch-based modeling: To create and edit design drawings based on freehand sketches to generate 3D models [52]. Creation could be based on four modules: (i) Sketch acquisition, whereby the vector data is originated from the user’s tracing of a stylus as line sequences, possibly registering variations in strokes depending on input pressure for further use. (ii) Shape recognition, it should parse acquired sketches to discriminate shape primitives and other basic data. It should be possible to distinguish between strokes meant as model geometry and strokes meant as complementary graphics (architectural symbols, annotations). Focus should be concentrated on 2D geometry recognition, since is what architects mostly use [18].The pressure variation should be used to inform shape recognition and define line types.The user intervention should be taken into consideration to take advantage of his/her visual intelligence in recognizing emergent shapes. (iii) Architectural interpretation, whereby architectural meaning should be assigned as to recognize geometry in its context (mass buildings, columns, walls, windows, etc.) and the spatial relations of these elements with the surroundings (i.e., the site), based on building geometry and complementary graphics. (iv) Reconstruction, to generate 3D geometry of interpreted elements through semi-automatic functions (generate automatically and offer interactive modifications). Preliminary performance simulations: To modify the model appearance temporarily, according to preliminary building performance results.A non-realistic visualization of the model could be provided along with the replacement of this visualization when the performance values are available [19]. On idle time or by user request, performance analysis and the display of the results could be directly obtained on the model, re-meshing it and using vertices to simulate physical consequences according to performance values. Preliminary performance simulations should be rough enough to assure fast executions and to respond accordingly to ill-defined situations typical of the early design stages. Interoperability for design stage transitions, where file formats should use the existing industry standards, in order to support interoperability with the application software broadly used in subsequent stages of architectural design, allowing a smooth transition.To target BIM

Supporting Tools for Early Stages of Architectural Design 505 interoperability, IFC format could be used. In a simplified approach, address interoperability just with software that is relevant to the stage following an early stage.The industry de facto standards are DWG or DXF (AutoCAD) and SKP (SketchUp) formats.This is central to facilitate importation and exportation of models and streamline design modifications back and forth. Without this integral support to the most important activities of early design stages, architects will continue to select traditional tools and media such as pencil and paper over digital technologies.The lack of support of these functionalities misses the application of these technologies, not meeting the demands of the practice, for architectural designs of increasingly efficient performance with decreasing delivery times.

5.A POSSIBLE SCENARIO OF USE The comparative analysis has supported a hypothetical scenario of use whereby different features could be supported.A building mass study exploring basic aspects of its environmental performance is used to trigger the conceptual solution.The different analyzed software were referenced as to demonstrate that the existing body of knowledge could be integrated in a single software.

Stage 1: Initiation of basic design The designer who has basic information on the spatial needs (design brief), opens the application to start drawing at the working space.With the stylus, he begins to trace strokes which are simultaneously displayed on the working space’s sheet in gradients of gray, resulting from different levels of pressure applied against the screen [49] (Figure 5, Left) as to assign primitive shapes to the different parts of the design brief.

Figure 5: Left: Strokes of an early sketch displaying real-time. Right: On idle time, strokes are automatically recognized as geometric shapes.

The two generated closed shapes are visually seen as different solids linked by a void establishing some tension between these two solids.As recognition is not on-line but on idle [18], the user moves hands away from the screen for more than four seconds and the software triggers the sketch recognition. Shortly thereafter, it shows recognized geometries in a brown color, differentiating these from sketch strokes, which remain in gray. Shapes are recognized as a circle and a closed polygon (Figure 5, Right).

506 Ernesto Bueno and Benamy Turkienicz As the designer establishes relations of proportion between shapes, understood as buildings, he uses the Orbit gesture to shift from the building footprint representation to its perspective to assign heights to the solids: touches both elements and, with a multimodal bimanual gesture [50], extrudes these in the direction and size of the traced line.To modify the heights, faces can be pushed to either direction of extrusion, similarly to [18, 47], but using the Drag gesture. The review of the created model with multi-touch navigation gestures, Orbit, Zoom and Pan, help the designer to generate alternatives, by modifying shapes and the spatial relations between them.With multimodal gestures, operations such as Move, Rotate, Scale and Stretch, can be performed in top view, for footprint modifications, and in perspective, for height control [18, 47].

Stage 2: Solid’s final delineation The building geometry can be adjusted in a section view through lines recognized as a set of polylines trespassing the solids (Figure 6, Left).This set, interpreted as a Section Line, acquires the color of symbols (red by default), as to differentiate it from the other graphic elements in process of modeling.

Figure 6: Left:Activating a section view. Middle: Redrawing Roof. Right: Verifying modifications in perspective.

Double-taping the Section Line symbol triggers the Section Edit mode to change view to elevation, showing the sectioned geometry and lines visible from the direction lines set.The geometry can be modified drawing new lines (Figure 6, Middle) and deleting the replaced ones, as in [49]. With the Orbit gesture, the drawing goes back to perspective as to check whether the solid geometry alteration fits the newly defined geometric condition (Figure 6, Right). Back to the plan view, the user draws the North symbol (Figure 7, Left). When the symbol is recognized, its topology matches the symbol database, as in [25], so it is interpreted as the coordinate system, giving orientation, information needed to simulate the performance with respect to environmental factors (for current date-time), such as shading. Once the simulation is displayed, the user navigates through the composition in perspective to inspect it (Figure 7, Right).

Supporting Tools for Early Stages of Architectural Design 507 Figure 7: Left: Drawing the North symbol. Right:Through interpretation of the North symbol, the system defines orientation and simulate shadings.

Stage 3: Performance pre-adjustments The shading simulation can be used to address the problem of excessive solar radiation on some façades thus emulating changes in orientation of the composition through the rotation of the solids in the plan view (Figure 8, Left). Once the transformation is finished, the user orbits to perspective and move hands away from the screen for four seconds, making the application to recalculate the shading simulation (as responsive as simulations in [19]) (Figure 8, Right).

Figure 8: Left: Rotating the composition in plan view. Right: Recalculation of shading simulation for rotated elements.

Stage 4: Façade design Modulation can be used to structure the solid’s façades: in a blank space, an X-shape polygon is drawn and thickness is applied along with a short extrusion (Figure 9, Left).Through bimanual gestures, the drawing is copied on a matrix array overlaying the surfaces of one of the solids, as in [30, 31] (Figure 9, Middle).After the transformation, idle time triggers the shading recalculation (Figure 9, Right).The experimentation could be extended further, consisting of several iterations of geometric editing and verification of the shadow impact, until the designer is satisfied with the developed architectural parti. Once this resolution level is reached, the model can be

Figure 9: Left: Drawing of façade module. Middle:Assigning module to repeat on surface. Right: Façade applied and shading recalculated.

508 Ernesto Bueno and Benamy Turkienicz exported to other software to continue the design development in its subsequent stages, as in [45, 49].

6. FURTHER DEVELOPMENTS The software integrating different software features highlighted in this article could be immediately implemented. Beyond implementation, however, some topics will need further development such as: • Studies on sketch recognition as to differentiate between reasoning sketches and prescriptive sketches [13]. For reasoning sketches, recognition of images by vectorization and geometric analysis, as in [5, 53, 54, 55], could be considered as methods to emulate shape emergence. • Studies on shape interpretation in architectural and urban contexts to identify different classes of elements (e.g. streets, city blocks, lots, buildings), considering the work of Kelly and Gero [23] and Turkienicz et al. [56]. • Interaction and usability evaluation tests with end-users. Further research can encompass other issues such as: • Integration with interactive maps (web services) to define the geolocation, orientation and scale of the project. • Collaborative design functionalities, considering the recognition of communicative sketches as proposed by Company [13] with a sign vocabulary related to drawn gestures. • Video and audio capture from webcams, allowing think-aloud processes and interaction with gestures in the air for augmented reality visualization, as in Araujo et al. [57]. • Parametric design sketches, defining geometric constraints from signs as in Naya et al. [49]. There is much work ahead and many development opportunities but is clearly remarkable the rescue of a classical discussion in the computation field, between the computer vision and knowledge-based computing and, at the same time, repositioning these non-excluding visions within the computer-aided design field, as envisaged by computer graphics pioneers.

ACKNOWLEDGEMENTS Thanks to Renato Silveira, Lennart Poehls and Professor Luciana Nedel for their advice.This research has been partially supported by FAURGS and by CAPES – Brazil.

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Ernesto Bueno and Benamy Turkienicz Federal University of Rio Grande do Sul Laboratório para Simulação e Modelagem em Arquitetura e Urbanismo Rua Sarmento Leite, 320, sala 306 Porto Alegre 90020-150 Brazil [email protected], [email protected]

512 Ernesto Bueno and Benamy Turkienicz