From: AAAI Technical Report SS-02-08. Compilation copyright © 2002, AAAI (www.aaai.org). All rights reserved. Functional and Formal Reasoning in Architectural Sketches Ellen Yi-Luen Do DesignMachine Group Departmentof Architecture,University of Washington Seattle, WA98195-5720 [email protected] Abstract arguments hold true especially in the domain of Architectsuse different symbolsand configurations in their architecture wherethe tool of the trade is drawing(Do and drawingsto explorealternatives and to communicatewith Gross 2001). each other. Theyuse sketches to performfunctional and Weare interested in building computational tools to formalreasoning in their designprocess. For example,when support design reasoning throughthe interface of freehand thinking about spatial arrangements,they draw bubble sketching. In this paper, we first report our research on diagrams;when thinking about natural lighting, theydraw a empirical studies of design drawingsin both the functional sun symboland light rays. This paperreports the findings and formal aspects. Wethen describe somecomputational fromempirical studies of drawingsand reports the software tools built to support designing. Finally, weconclude with systems that were implementedto support intention inference and automatedactivation of knowledge-based discussionsand possible future researchdirections. designtools to supportdesign. Studies of Design Sketches Why Study Design Drawing Wehave conductedseveral empirical studies on design and In the early design process, designers draw diagramsand drawing to determine whether, and to what extent, it is sketches to explore ideas and solutions. Drawings are possible to infer, interpret, or even guess whata designer mental tools. Architects sketch to help themselvesto see was thinking about by looking at the drawingshe has made. and understand the form they work with, and to Weare interested in howdrawings get made, and what communicatewith others. Despite the fact that these specific knowledgeand reasoning process they represent. drawings may seem crude, they are valuable in Specifically, we are concernedwith the thought processes understanding how designers work because each of them that underlie the operations comprising a drawing. serves its purposein a workof importance.Each line in a Therefore, these empirical studies were conductedfocusing drawingplays a role. It couldrepresent an outline of a form on design problem solving with form or function, or a path of force (e.g., wind, rain, or light ray). separately. Architectural design deals with both formand function. The studies include 1) data analysis of 62 architecture The activity of drawing includes both seeing and students’ concept diagramming,2) video transcripts and thinking about the subject being represented. Design protocol analysis of four architects conductingdesign of an drawing is an iterative and interactive act involving architect’s office, and 3) a retrospective analysis of recording ideas, recognizingfunctions and meaningin the pavilion house design that was carried over the period of drawings, and finding new forms and adapting them into 15 years by an architect. the design (Goldschmidt 1991; Sch6n and Wiggins 1992; Suwaand Tversky 1996). It serves as external symbol Functional Reasoning systems to facilitate thinking and support emergentideas The first study used design stories and diagrams from a (Goel 1995; Fish 1996; Mezughi1996). case-based design aid called Archie (Kolodner 1991; Recently we have seen research workand computational Domesbekand Kolodner 1992; Zimring, Do et al. 1995). systems to support sketching in various domains(Hearst, The database library of Archie contains stories, problems Gross et al. 1996; Stahovich 1996; Landay and Myers and responses from post-occupancy evaluation data 2001). For example,a user can sketch widget symbolsfor collected in field studies of ten courthousesand libraries. interface design (Landay1996) or military course of action All related items are cross-linked. Each participant were planning (Forbus, Fergusonct al. 2001). Theyargued that given the tasks of makingdiagrams from stories, writing electronic sketching tools provide designers focus on the stories fromgiven diagrams,pairing diagramsand stories, task at hand, on spatial relations andstructure of the design and commentingon existing Archiediagram-story pairs. instead of specific detailed look and feel of the drawing The second study involved protocol analysis of four (Ferguson 1992; Landay and Myers 2001). These designers in action. The designers were first given a 37 programbrief of an architect’s office space design. After reading the design program,designers were asked to start Formal Reasoning with a newsheet of paper (or tracing paper) for each task The third study is a retrospective analysis of the pavilion and to focus on four different concerns in conceptual, house design drawing. Over the course of 15 years, the schematicdesign. The tasks include 1) spatial arrangement, architect had been engagedin formal manipulationsof the 2) lighting, 3) visibility andprivacy, and 4) fitting a special piece of furniture into the design. designfor a residenceand archivedall the drawinginto six CD-ROMs.We looked at 110 drawings selected by the Fromthe diagrammingexperiment (Do 1995) and design architect and developeda coding schemeto classify these protocol analysis (Do 1997) we found that designers use drawingsinto different categories. This study resulted a graphic symbolsto represent certain physical objects and design tasks and concerns. For example, when thinking conceptual frameworkto account for connections among about spatial arrangementsof functional spaces, designer the drawings(Neiman, Do et ai. 1999). Ourstudy attempts would draw bubble diagrams to represent the rooms and to identify relationships betweendrawings in order to their connections. They also drew graphic symbols for understandthe role of formal reasoningin a design process. furniture objects to put themselvesin the context of the Whatbegan as a thought experimentresulted in a range of plausible interpretations to account for what might have design problems. Whenthinking about lighting concerns, a actually happened in the design process. The designer woulddraw a configuration consisting of an arrow interpretations were madethrough several iterations of penetratinga vertical rectangle, representinga light ray in a sorting, classification and coding. Theresults werelater sectional view. Figure 1 shows examplesof the diagrams comparedwith the designer’s retrospective examinationof drawnby the participants. the drawings. (Ell Pipe I.Iootrmnq~(E7) Bodybox 1|61 IF.d) Chirnneyh~’~F-l:nkl ~ eacmYm’*) R15) Hernial sgtlpa, ~===- ilk ~ me (E’I4! co~rnn~t) (EI~,)Ve~lcu window Wall(E2) Figure3. Principalarchitectural elements for the PavilionHouse Figure I. Drawingconventions: (a) bubblediagram for spatial (withcoding for elementtypes). arrangement,(b) graphicsymbols for furniture layout, and(c) lightingconcerns in sectionalview. Manyof the drawings are composedof more than one drawing and consist a compositionof plan, sectional, or Designersalso wrote text to label the functions or names isometric viewsof the floor plan, or study variations of a of the space. Whenthinking about fitting a piece of fagade. Wedivided the compositedrawings into individual furniture in a conference room, designer wouldnot only drawings and coded them with unique identifiers and draw graphic symbolsfor furniture but also dimensional drawing properties. The schemecodes properties of the markers and numbersto reason about dimensions. drawings such as the elements depicted as well as projection types and viewangles of the building. Figure 3 shows the commonarchitectural elements and their codes P 4* I0-40 (in parenthesis, e.g., El represents a column, and E2 section Iff represent a wall). Figure 4 shows a drawing coded of bufferfor table 40*2=80 elementtypes, location and mediumused. ©onfcrcflc¢room ID# Drawing Elements Location Medium 3" lff-~T ~.- ..-D 20’’10’ ,,2(X)~l. /scale ffi 37’ = ....... !_ PI-30 El, E2, E3, pencil Figure 2. Dimensionalreasoning for spatial arrangement CPl-9a) E4, ES, E6, MI) P2-16 E7, ES, E9, accordingto programsquare footage requirements(numbers, P2-15) El0, El2, ~ciiow, markersand calculations) El2, El2, blue, red El2, El2, markers For example,a participating designer drew dimensional El3, El4, M4) markswith 10’ intervals along the length of the site (three El5 1 O’s and a 7’). Thenhe checkedto see if the table couldfit Figure4. Adrawing in codedtable of differentclassifications. into the conference room(20"10). First he wrote downthe dimensionof the table (4"10), calculated and wrote down For any two drawings, the coding schemealso accounts the answer40, and doubledit (80) for buffer space. Figure for the transformations of the design elements such as 2 shows the drawing and annotations of the reasoning geometrictranslations of shapes, locations and color. The process derived from the verbal protocol. letter codes E, L, T, and C correspond respectively to elementidentifiers, location identifiers, and transformation types, and C specifies the use of a color. D indicates the 38 projection type, V the view direction, M the drawing The East Building was designed to extend space for medium,and I the designer’s self-described intention in programming and to act as complement to the West makingthe drawing. For example,the expression Building. It was a design task to provide not only organizationand