playing with design intents: integrating physical and urban constraints in cad

Automation in Construction 9 (2000) 93–105www.elsevier.com/ locate /autcon

Playing with design intents: integrating physical and urbanconstraints in CAD

*Didier Faucher , Marie-Laure Nivet´ ĆERMA, Ecole d’Architecture de Nantes & IRIN, Faculte des Sciences et des Techniques de Nantes, Nantes, France

Abstract

Our work deals with the exploration of a universe of forms that satisfy some design intents. That is, we substitute a‘‘generate and test’’ approach for a declarative approach in which an object is created from its properties. In this paper wepresent an original method that takes into account design intents relative to sunlight, visibility and urban regulation. First ofall we study how current CAD tools have considered these properties until now. Our conclusion is that the classicaldesign/simulation /analysis process does not suit design practices, especially in the early stages. We think that an improvedCAD system should offer the architect the option of manipulating abstract information such as design intents.

We define an intent as a conceptual expression of constraints having an influence on the project. For instance, a visualintent will be stated with no reference to vision geometry: ‘‘from this place, I want to see the front of the new building’’. Weshow how to represent each of these constraints with a 3D volume associated to some characteristics. If some solutions exist,we are sure that they are included in these volumes. For physical phenomena we compute the volume geometry using theprinciples of inverse simulation. In the case of urban regulation we apply deduction rules.

Design intents are solved by means of geometrical entities that represent openings or obstructions in the project.Computing constraint volumes is a way of guiding the architect in his exploration of solutions. Constraint volumes are newspaces that can restore the link between form and phenomenon in a CAD tool. Our approach offers the designer thepossibility of manipulating design intents.

´Le jeu des intentions: integration de contraintes physiques et urbaines en CAO

` ´ `Notre objectif est d’offrir a l’architecte les moyens d’explorer un espace de formes defini a partir d’intentions de conception.` ` ´ ´ ´ ´ ´ `Parallelement a l’approche du type generer / tester, nous proposons une approche declarative dans laquelle l’objet est cree a

´ ´ ´ ´ `partir de ses proprietes. Nous presentons dans cet article une methode originale de prise en compte, dans un systeme de` ´ ĆAO, des intentions de conception relatives a l’ensoleillement, la visibilite et la reglementation urbaine. Dans un premier

` ´ ´ ´temps nous relatons de quelle maniere ces proprietes sont prises en compte dans le processus de conception assistee par´ órdinateur. Les outils actuels imposent de construire une maquette numerique du projet avant de pouvoir en etudier les

´ ´ ` ´ ´differentes caracteristiques. Le constat que nous pouvons dresser a la suite de cette etude est que le cycle modelisation d’une` ´ ´scene, simulation, analyse des resultats est mal adapte aux phases amonts de la conception, lorsque le projet est encore mal

´ ` `defini. Il parait souhaitable, dans un systeme de CAO, d’autoriser l’architecte a manipuler des informations d’un haut niveaud’abstraction: les intentions.

´ Ńous definissons une intention comme l’expression, sous sa forme conceptuelle, d’une contrainte imposee ou non,´ ` ´ ínfluencant le projet. Par exemple, une intention visuelle sera exprimee sans avoir recours a la geometrie de la vision qui lui

ˆ ést sous-jacente: ‘‘de cette place je veux voir la facade du batiment projete’’. Nous montrons pour chacune des contraintes

*Corresponding author.E-mail addresses: [email protected] (D. Faucher), [email protected] (M.-L. Nivet)

0926-5805/00/$ – see front matter 2000 Elsevier Science B.V. All rights reserved.PI I : S0926-5805( 99 )00046-1

94 D. Faucher, M.-L. Nivet / Automation in Construction 9 (2000) 93 –105

´ ´ ćonsiderees qu’il est possible de representer ses conditions de satisfaction sous la forme d’un volume en trois dimensions´ ´ ´ ´ ´dote de certaines caracteristiques. Ces volumes geometriques representent des sous ensembles de l’espace portant les

´ ´solutions, si elles existent. La geometrie d’un volume est obtenue en utilisant les principes de la simulation inverse en ce qui´ ` ` ´ ćoncerne les phenomenes physiques, et par l’application de regles de deduction pour les contraintes reglementaires. Le calcul

´ ´de ces volumes nous permet de guider l’architecte dans son exploration des solutions, masques ou evidements, qui resolvent´ ´les intentions enoncees quelque soit leur type.

Ćes nouveaux espaces de recherche que constituent les volumes de contraintes retablissent, dans une certaine mesure, le´ `lien entre forme et phenomene en situation d’utilisation de l’outil informatique. Notre approche offre au concepteur la

´ ´ ´ ´ `possibilite de mener un veritable jeu d’intention, en lui permettant d’etudier differentes hypotheses de conception. 2000Elsevier Science B.V. All rights reserved.

1. Introduction cess. This is not always possible because of fixeddecisions.

Our work deals with the exploration of a universe Moreover, as shown by some observations, theof forms that satisfy some design intents. That is, we way an architect works is modified by the use of asubstitute a ‘‘generate and test’’ approach for a CAD system. In such a context he is often wrappeddeclarative approach in which an object is created up in geometrical aspects instead of consideringfrom its properties. This paper presents a hypotheti- physical and realistic features which determine thecal project dealing with the representation and the ambience of his project. Thus, sketching with CADintegration of physical and urban constraints in a tools does not permit to state the design problem anddesign process. It is not concerned with the presenta- to explore more than one solution. Such systems aretion of an operational system that can be integrated only drawing and visualization tools. For some years,into a real design process. we have seen various attempts to remedy this

During the early stages of architectural design, the situation. Especially, it has been demonstrated thatdesigner must deal with various constraints. Some of reverse simulation methods lead to parameter valuesthese, (like urban regulation), take on an imperative meeting lighting properties and visual constraints. Bycharacter. Some others result only from design these means, the architect devotes his time to ex-intents that follow the customer’s requests or ar- amining multiple hypothesis of design instead ofchitect’s desires. The visual impact of the project, its searching how to satisfy one given property. To playlighting qualities or its thermal and acoustical prop- with design intents it is necessary to solve someerties have to be considered. The choices made at difficulties: on the one hand, how to take intothis preliminary step will determine the global account the multiplicity of solutions; on the otherevaluation of the proposal. Analysis tools, which are hand how to integrate several phenomena.required to grasp such qualitative factors, are not yet In this paper three kinds of properties will beintegrated into CAD systems. These latter only considered: urban planning regulations, lightingconstruct a geometric model that is used to simulate properties, and visual constraints. We make a briefsome phenomena or make realistic images. In fact study of relative works in design context. We willthese processes are only applied to validate or to show how to represent these properties by a 3Dinvalidate some previous choices. These tools require volume associated with some characteristics. Mecha-a full description of the structure and so they cannot nisms to explore the set of solutions included in abe used before the last stage of design. The project constraint volume will be described. The solutionhas to be well-defined and well-known to be tested. space generated by the intersection of two or moreThe designer follows a generate and test process: he constraint volumes will be outlined. All these pointsthinks about his project, makes some simulations on will be studied in view of the architectural design.it and he observes the results. If his intents are not The pedagogic advantage of our approach will bereached, the designer has to repeat the whole pro- discussed. Finally we will conclude with a discussion

D. Faucher, M.-L. Nivet / Automation in Construction 9 (2000) 93 –105 95

about the benefit of such a representation in the bourhood. Knowledge-based systems can offer assis-design process. tance to the energy saving [9]. From simple rules

derived from statistics these systems propose solu-tions with aim to improve the project by modifying

2. Physical and urban constraints in design its materials.

The architect has usually to adhere to a program 2.2. Visibilitythat takes into account some features of the site, thebudget allocated to the operation, as well as the The increasing interest in a project’s integrationwishes of the customer. The designer completes this into a site, the legibility and the spatial compositiondocument with his own considerations (aesthetic, encouraged the development of simulation toolsfunctional . . . ). The architect playing with this set of about visibility and more particularly about theparameters must come up with a suitable compro- visual accessibility. A lot of numerical tools rest onmise in the form of an architectural or urban shape. the use of the isovist [10] which can be defined asSome elements, such as the visibility or the urban the set of points that are visible from a particularregulation of the site, are part of the program, or point or space. Several mathematical and/or intuitivesometimes predominant [1]. The building position relations [10] allow one to describe the architecturalwith regard to public roads, or the will to provide a space [11,12]. The isovist is also the kernel of somegood quality of sunlight to the project will have other systems dedicated to the study of urban [13]some direct effects on the constructed shape. Many and landscaped [14] spaces. In urban environmentcomputer tools allow one to analyze projects from we can also mention [15] making use of a sunlightthe point of view of different phenomena. We present simulation tool [6] to allow visual accessibilitya brief state of the art in the following paragraphs. analysis. Software can also help in the choice of

We consider exclusively numerical systems related locations for disruptive elements like high-tensionto the three following aspects: sunlight, visibility and lines [16,17].urban regulation. Though they bring a lot of ele-ments to the reflection, we omitted the other methods 2.3. Urban regulationvoluntarily (graphical, analog . . . ). The reader willfind more details in [2] concerning sunlight, [3] for Reflections on our modern cities’ loss of urbanityvisibility and [4] for urban regulation. have motivated the setting up of analysis and simula-

tion tools. The development of geographical infor-2.1. Sunlight mation systems (GIS) is an illustration of this. These

systems try to integrate a lot of geographical, econ-Numerical methods dealing with sunlight can be omical [18] or environmental [19] measurements.

classified in two categories: the ‘‘classical’’ systems They sometimes integrate multiple components likeof simulation which determine the distribution of geometric modelers and rendering tools [20].sunny and shaded spaces during a temporal interval, Early works related to urban planning which havein a given scene; and the knowledge-based systems taken into account regulations made use of tech-which give some help in the use of materials and the niques derived from expert systems. Though theyglobal organization of building forms. The former have brought some results [21,22] these approachesbenefited from works in geometric modeling and in suffer from a lack of interaction and can not be usedimage synthesis. They use either perspectives or in the process of urban planning as it is exercisedorthogonal projections [5–7], or ray tracing [8]. nowadays. This shortcoming is caused by the waySunlight maps (in two or three dimensions) are information is represented in such systems. Adoptingcomputed. It is possible to superimpose them on the a more interactive approach, the system proposed innumerical model of the site. Then the designer can [23] is available to the architects and other particip-judge the sunlight distribution and the potential ants in the shaping of the urban form.interactions between the building and its neigh- To our knowledge, little work has been done in


this field during recent years. It seems that the study high level of abstraction: that is to say intents. Weof the regulation aspects has been forsaken for the define an intent as a conceptual expression ofone related to negotiation processes. Today, the constraints having an influence on the project. Formanagement of urban environment, especially in instance, a visual intent will be stated with noFrance, is also done by means of rules. These latter reference to vision geometry: ‘‘from this place, Icontrol the morphology of the building form. How- want to see the front of the new building’’.ever, without reducing the urban planning to the The usual cycle of simulation tools is reversedapplication of urban regulation, it is necessary to manipulating intents in a computer aided designnotice its importance on the shape of a city. An process. On the left side of Fig. 1 the classic cycle isinteresting approach of the modeling of the link represented: numerical modeling of the scene, simu-between building shape and urban shape is de- lation, result analysis. This cycle leaves no room forveloped in [24]. graphical simulation as we defined it previously.

Design is achieved outside of the system which onlymanipulates the geometry of the project. Our ap-

3. Design by intent proach of design by intents is represented on theright side of Fig. 1. The architect interacts with the

The direct simulation tools which have been system by expressing his intents. The system haspresented above only permit a validation of a project. enough knowledge to interpret them as a space ofThey do not support the uncertainty inherent in solutions that the architect is free to explore graphi-architectural design, especially in early stages of the cally. We stress the fact that the system producesproject. The architect then manipulates only some only geometrical shapes. We intentionally leave theideas or abstract shapes. For instance he can realize architectural interpretation (concept, materials, aes-some annotated sketches which inform on the atmos- thetic or economical qualities . . . ) to the designer inphere and the genius loci of the project. The designer order to preserve the creative nature of this process.plays with these elements and thus simulates graphi- In a simulation cycle (left part of Fig. 1) a newcally [25] different solutions. Without aiming to numerical model of the scene starts the iteration. Inpropose a computer version of a ‘‘sketch notebook’’ the inverse approach (right part of Fig. 1) a newand thus fall into the Dr. Pangloss fallacy [26], it cycle starts by the statement of new intents or by theseems to be interesting, in a CAD system, to allow refinement of the previous ones. The two approaches,the architect to manipulate some information of a direct simulation and design by intents, are com-

Fig. 1. Interaction between simulation and design by intent.


plementary. The results of one can be input data for Urban regulation is not based on a physicalthe other. The introduction of intents within a CAD phenomenon but on the politics of management ofsystem induces a new formalism of representation. the city’s spaces. Here, we only consider rulesThis is the object of the following section. influencing the building’s shape. In France, these

rules are generally defined in articles of a ‘‘pland’occupation des sols’’ (POS). A POS is a completedocument in which plans mention existing construc-

4. Modeling design intents tions and zones of regulation. Every regulationarticle participates in the definition of one or several

In the following, we speak of ‘‘intents’’ when we volumes of constraints.refer to the interaction designer /project /CAD tool.We use the term ‘‘constraint’’ when these intents aremanipulated in the computer system. 4.1. Geometric representation of constraints

We conjecture that a class of intents can bemodeled by some geometric volumes of constraint. A survey of the representation for each kind ofThese geometric volumes represent subspaces in constraints is developed in [2] for sunlight, [27] forwhich the solutions are included (if they exist). The the visibility and [28] for urban regulation. Wegeometry of a volume representing a set of solutions present the main parameters of each model in Figs.is obtained using the principles of inverse simulation 2a–c. Each figure indicates an example statement ofwhen treating physical phenomena, and using deduc- intent, summarizes the essential parameters of thetion rules for urban regulation. The inverse simula- model, and shows an example of the constrainttion derives its name from research done in physics volume geometry.or in mechanics. By reversing the equations related We can ensure that if a solution to the expressedto a phenomenon, it is possible to find the input intent exists, it is included in the volume of con-parameters of an equation system satisfying a given straint computed by the system. A solution is astate. geometrical entity, which satisfies a constraint. We

The visibility and sunlight phenomena can be insist on the fact that the architectural meaning ofexpressed following the same principle based on the this raw shape is given by the designer and not bynotion of rays (left side of Fig. 2). Reversing the CAD system. For example a surface or a volumesunlight or visual ray (Fig. 2 on the right) allows to will be interpreted as a building front, a sunshade orfind the corresponding constraint satisfaction sub- a tree. An empty space will be seen as a street, anspace: the volume of constraint. aperture or a passage.

Fig. 2. Direct and inverse line of sight or sunbeam.


Fig. 2c. Urban Intent: ‘‘The building must be included in theFig. 2a. Sunlight Intent: ‘‘The front of the project must be sunlitmaximal volume of the site.’’ Parameters needed: plot geometry;in the middle of the evening in winter.’’ Parameters needed: timemaximum building heights; width of the surface to be built; depthperiod, the qualifying surface represented as a polygon. Qualifica-of neighboring houses. Qualification: can be built; cannot be built.tion: sunless, sunlit.

In an architectural context, an intent is realised by positive constraint: constraints which are resolvedmanipulating some full elements or empty spaces. using one or several solid elements are defined asThis is the reason why it is possible to treat the positive; constraints which are resolved using one ordescriptions see /don’t see, sunlit / sunless, can be several empty spaces are defined as negative. As forbuilt / can not be built, in a same way. Thus con- sunlight and visual properties, the positive con-straints of different kinds are considered homoge- straints are resolved adding some solid elementsneously by introducing the notion of negative or intercepting all the rays of constraint volumes. The

negative constraints imply a total hollowing out ofthem. In the case of urban rules, the solutions do notdepend on the direction of rays. The only thing to beconsidered in the determination of the solutions isthe presence or the absence of matter.

In the examples presented hitherto, we alwaysconsidered binary intents, that is to say some ‘‘all ornothing’’ statements: ‘‘see entirely or don’t see atall’’. In many cases, it is interesting to study intentsfinding their solutions between these two states. Inother words we have to enrich the formalism topermit the statement of non-binary intents like‘‘build at least 50% of the front wall in the border ofroad’’ or ‘‘from this street see a part of the front ofthe new building’’. Applying the representation wechose, the state of an intent (positive, negative,binary, non-binary) generates a constraint. The sub-space including the potential solutions is representedby a volume. The geometry of a constraint volumedoes not depend on the description it is linked to.This description is taken into account during theexploration step of the solutions space (Fig. 3). A

Fig. 2b. Visibility Intent: ‘‘From the square, the observer must benegative binary constraint is achieved only if theable to see the front of the church.’’ Parameters needed: Observer,corresponding volume is empty. If the constraint isdefined by his view field and location; object in the environment.

Qualification: to see, not to see. already satisfied, the system prevents any addition of


Fig. 3. The ratio of description /number of solutions.

solid in the volume. On the contrary, if the constraint tives are not to propose an automatically-generatedis not satisfied, the resolution consists in hollowing solution. We wish to offer the designer tools that heout the constraint volume. This solution is unique; it will be free to use during the design process. Foris necessary and sufficient. The resolution of a these reasons, we can not limit ourselves topositive binary constraint is more problematic, in- enumerating all the solutions or randomly choosesofar as an infinity of solutions exist. Indeed, in the one solution. Such a procedure would be inapplic-case of a visual constraint, an infinity of obstructions able considering the big number of shapes to ex-that cut all the lines of sight can be defined. Finding amine. Keeping this philosophy in mind, we studya solution is the same as choosing a obstructing first the possibilities for solutions in the case of aobject among this infinity. The process is identical in single constraint.the case of the non-binary solutions (positive ornegative). For example in the case of the ‘‘boundaryline rule’’, used in the POS, only the solid /empty 5.1. Positive binary constraintratio is imposed: the designer has to find a dis-tribution of the wall along the road that satisfies this For such a constraint, the simplest case consists incondition. manipulating a structural plane holding a blocking

object (Fig. 4a). Applying some geometric trans-formations on this plane (rotations and shifts) the

5. Explorating solutions of a constraint user manipulates the blocking object indirectly. Thesystem controls the degrees of freedom of the plane

We stress again the fact that our research objec- and computes the minimal blocking object. This


Fig. 4. Principles of interaction with solutions.

object is the intersection surface between the plane volume. The user can then put a second tool volumeand the constraint volume. Another possibility is to (volume 2) in order to complete the first occludinguse a so called tool volume which intersects com- element.pletely the constraint volume as it is shown on Fig.4b. A tool volume is represented in the horizontalplane. Its intersection with the constraint volume is 5.2. Non-binary constraintindicated in grey. It constitutes an exact blockingobject. A designer could interpret this volume as a We recall here that a non-binary intent is agroup of trees (Fig. 4c). Note that such a volume can statement that introduces a new degree of freedom inbe reduced to a surface. the satisfaction of a constraint. Let us take the case

In order to allow more flexibility in the manipula- of the maximum building surface. It requires thattion of the blocking objects, we also propose to only 80% of the plot surface be constructed. Thisexplore the possibilities of non-connected solutions. constraint can be satisfied in different ways as shownExtending the previously described interaction in Fig. 5.means, we allow the designer to manipulate several The user distorts his solution while the systemtool volumes. The user indicates the number of ensures that the surface respects the stated per-elements to put in order to satisfy the constraint. In centage. Such a constraint can be also solved man-Fig. 4d, a first tool volume is drawn (volume 1). It ipulating directly the building plot surface. In thisdoes not resolve totally the constraint. Consequently case, the system reduces the solution space andthe system computes the complementary constraint proposes a new constraint volume according to the

Fig. 5. A non-binary constraint example: building land surface.


Fig. 6. Solutions in the intersection of two constraints.

given percentage. So the new volume can be ex- tions. We can work outside of the intersection of theplored as a binary constraint one. constraint volumes, thus we go back to the explora-

In a more general way, all non-binary constraints tion of several unique constraints; or inside thecan be treated by graphic interaction on the solution intersection space exploring all the constraint vol-or by refinement of the intent. The exploration by umes simultaneously. The intersection between sev-refinement process permits a real game with intents. eral constraint volumes rarely ensures the completeIn a real situation, the multiplicity of the constraints resolution of all the considered intents. That is to sayrequires this game because it is often difficult to find that one blocking object can not satisfy all thea compromise without coming back to the initial constraints completely. However, it is of interest tointents. work in this space when the solution has to be

optimized. This search is difficult because of the5.3. Interaction in multiple constraints complex geometry of the intersection volume, com-

bined with the fact that we have to take into accountThe statement of several intents brings some the direction of the rays. A first approximation of the

situations of competition or opposition between solution consists in offering the whole intersectionthem. Searching for a solution requires in the first volume (Fig. 6b). However some other obstructionsplace knowing the usable zones (i.e. where it is are acceptable (Fig. 6c).possible to put some solids). This is why the negative We are currently proceeding to the survey of thebinary intents must be solved in priority by hollow- properties associated with intersections of constrainting out all the volumes of the negative binary volumes. We classify the faces and the edges of suchconstraints. The search space is thus reduced to the an intersection with the object in order to extractvolumes of the remaining constraints, minus their search methods for solutions. This classification willpossible intersections with the volumes of negative allow us to know the function of each volume face inbinary constraints. The geometric representation of the resolution of the constraints (rate of resolution,intents allows seeing the zones of the space where constraint involved). This study will help us to assistthey interact. These subspaces are the zones of the designer in his search for an optimal solution.intersection between the constraint volumes. Thesezones are qualified by all the intents engaged. Thenwe have to find a solution that can be inserted in this 6. An exampleintersection space.

Fig. 6a shows the competition between a visual The example presented in this section shows howand a sunlight constraint. The rays which define visual and urban intents are taken into account in ourthem, are not directed towards the same direction. A system. The project consists of building a culturalsolution has to intercept all the rays in both direc- centre in a given urban environment. An auditorium,


Fig. 7. The site or plan geometry.

a reception hall, and various administrative office the land plot to be built and he chooses the rules tospaces are included in the program. Besides, the apply. In this example the maximal volume rule, theauthorities of the city wish to keep a good visibility height rule and the standing back rule are used. Theof a great building near the project land plot. building land surface is not considered.Furthermore the urban rules lay down the respect of The visual intent ‘‘see the monument’’ is athe building outline. Fig. 7 presents in dark grey the negative binary constraint competing with the posi-land plot to be build and in light grey the monument tive non-binary constraint volume defined by thewhich the visual constraint is based on (in stippled). urban regulation (Fig. 10). With regard to the priorityThe outline building rule gives a first approximation rule, the system proposes to hollow out the outlineof the volume approved for development (Fig. 8). In volume (Fig. 9).concrete form, the user inputs his visual intent in the The resolution of the visual intent leads to asystem by drawing the position of the observer volume sketch for the architect to work with. He can,(point, segment line, or convex plane surface) and by for example, plan to use the upper part for thepointing out the target (a surface). The user selects auditorium. The reception hall will take up the lower

Fig. 9. Hollowing out building outline.Fig. 8. Outline of the building.


Fig. 10. Intersection of visual constraint and site.

part of the volume. The designer thinks aboutbuilding a big picture window on the back but hewishes to conserve the privacy of the hass as well.He will therefore state a new intent: ‘‘from thewindows of neighboring buildings don’t seel all ofthe hall (i.e. not picture window). With this as hisgoal, he selects the picture window’s surface to bethe target objects and selects the windows of theneighboring buildings as observation points (in ourcase four points). Fig. 11 shows the constraintvolumes thus generated.

In order to respond to this new constraint, thearchitect could decide to place the administrativeoffice spaces to the rear of the land plot. Theseoffices will be used for occluding the neighboringfacades and thus to satisfy the privacy intent.

7. Conclusions

In this paper we have presented an originalmethod for taking into account, in a CAD system,intents related to sunlight, visibility, and urbanregulation. We explained the principles of computingconstraint volumes engendered by the statement ofintents. We have shown that it is possible to unify themethod of searching for solutions in these constraintvolumes. Constraint volumes constitute new searchspaces that restore, to some extent, a link betweenshape and phenomena in a CAD tool.

Our approach is of interest from two points of Fig. 11. Translation of the privacy intent.


´[4] J. Dubois-Maury, L’amenagement urbain, in: D. Paris, Outilsview. Firstly, in the context of teaching Architecture,juridiques et forme urbaine, Collection pratique de l’Im-making phenomena concrete in a virtual design spacemobilier, 1996.

leads to a better understanding of them. An Architec-[5] K. Grau, K. Johnsen, General shading model for solar

ture student can freely manipulate these phenomena building design, ASHRAE Transactions 101 (2) (1995) 13.and the shapes that are generated. Second, in a [6] D. Groleau, C. Marenne, A. Gadilhe, Climatic simulation

tools: an application for a building project in a urban space,real-life situation our direct simulation approachSolar Energy in Architecture and Urban Planning, Proceed-allows one to visualize the behavior of severalings of 3rd European conference on architecture, Florence,shapes representing some phenomena. The architect1993, pp. 346-349.

describes his project precisely only when he has [7] A. Yezioro, E. Shaviv, Analysing Mutual Shading Betweenfound an acceptable compromise by playing with Buildings in an Urban Environment, in: Proceedings of

PLEA’94, 1994.intents.[8] D. Siret, Sunlighting Design: An Inverse Approach ofCurrently every phenomenon is processed by a

Simulation for CAD Tools, Advances in Computer-Aideddifferent system. We propose this unique tool withDesign, Proceedings of CADEX’96, 1996, pp. 32–40.

the hope of furthering students and practicing ar-[9] G. Sylvestrini, S. Cacopardi, Uses of an Expert System for

chitects’ interest in the method of design by intents. Passive Cooling Building Design, in: Proceedings, ThirdThis research, only in its initial stages, must thor- European Conference on Architecture, Solar Energy in

Architecture and Urban Planning, Florence, 1993, pp. 358-oughly examine how to deal with interactions be-360.tween constraints. Some work in this direction has

[10] M.L. Benedikt, To Take Hold of Space: Isovist and Isovistalready been done. In particular, we are studying theFields, Environment and Planning B 6 (1979) 47–65.

possibilities of exploration by graphical means in [11] M.L. Benedikt, C.A. Burnham, Perceiving Architecturalsome complex cases where an important number of Space: From Optic Arrays to Isovists, Persistence and

Change, in: W.H. Warren, R.E. Shaw (Eds.), pp. 103–114.intents must be considered. Without aiming at solv-[12] E.Y-L. Do, M.D. Gross, Tools for Visual and Spatialing all the constraints of an architectural or urban

Analysis of CAD Models, in: Proceedings of CAADdesign project, we wish to extend the formalism toFutures’97, Implementing Computer Tools as a Means to

other physical phenomena. In particular, we will Thinking about Architecture, Munich, 1997, pp. 189–202.have to study thermal or acoustical phenomena in [13] B. Hillier, Cities as movement economies, Urban Designorder to judge the relevance of our approach for International, Cambridge University Press 1 (1) (1996) 41–

60.taking them into account in the early stages of the[14] D.R. Miller, J. Morrice, P. Horne, R. Aspinall, Characteriza-design process.

tion of Landscape Views, Macaulay Land Use ResearchInstitute, EGIS 94 (1994) 10.

´[15] M. Morin, Lecture de la tour de Bretagne, developpementAcknowledgements ´d’un outil de lecture de la ville, simulation de l’accessibilite

visuelle, Ecole d’Architecture de Nantes, 1995.¨The authors are grateful to Marie-Joelle Antoine [16] M. Gro, The Analysis of Visibility, Environmental Interac-

and Franck Raymond for their assistance with the tions between Computer Graphics, Physics, and Physiology,Computer & Graphics 15 (3) (1991) 407–415.English version of this paper.

[17] H.-J. Koglin, R. Zewe, Valuation System for the Visibility ofOverhead Lines, Engineering Intelligent Systems 3 (4)(1995) 195–203.

References [18] P. Lahti, Geographic Information Systems (GIS) as aninteractive platform for economical management of urban

´ `planning, Ingenierie des systemes d’information 5 (2) (1997)´[1] MVRDV, Amenagement d’une place sur une ancienne gare241–252.`de triage a Bergen op Zoom, L’architecture d’aujourd’hui

[19] J. Danahy, R. Hoinkes, Polytrim: Collaborative Setting for306 (1996) 66-67.Environmental Design, in: M. Tam, R. The (Eds.), The´[2] D. Siret, Propositions pour une approche declarative desGlobal Design Studio, National University of Singapore,`ambiances dans le projet architectural. Application a l’en-1995.` ´soleillement. These de doctorat, Universite de Nantes, 1997.

´ [20] R.S. Liggett, W.H. Jepson, An integrated environment for[3] M.-L. Nivet, Approche declarative pour la prise en compte´ urban simulation, Environment and Planning B: Planningde l’accessibilite visuelle dans le projet architectural ou

´ and Design 22 (1995) 291–302.urbain, Rapport de recherche IRIN, no. 165, Universite de` ´ `Nantes, 1997. [21] M. Elmakhchouni, Contribution a l’etude d’un systeme


graphique intelligent pour la planification urbaine: [25] J.C. Lebahar, Le dessin d’architecte: simulation graphique et´ `SYGRIPOS simulation visuelle des plans d’occupation des reduction d’incertitude, Parentheses, Collection Architecture /

`sols. These de doctorat, Institut national des sciences ap- Outils, 1983, 134 p.´pliquees de Lyon, 1985, 167 p. [26] U. Flemming, Get with the Program: Common Fallacies in

[22] J. Rabie, Towards the simulation of urban morphology, Critiques of Computer-Aided Architectural Design, Environ-Environment and Planning B: Planning and Design, Com- ment and Planning B: Planning and Design 21 (1994) 106–puters in the modelling and simulation of urban built form 18 116.(1991) 57–70. ´[27] M.-L. Nivet, D. Siret, Simulation inverse de l’accessibilite

` ´[23] A. Dupagne, P. Leclercq, D. Pirotte, Systeme base sur de la visuelle en milieu urbain, Revue Internationale de CFAO,´ ` ´connaissance appliquee a la reglementation urbaine, 1998.

´´ ´EuroplA’88: Journees europeennes sur les applications de ` `[28] D. Faucher, Etude des regles urbaines relatives a la mor-ˆ ´l’intelligence artificielle en architecture, batiment et genie ˆ ´phologie du bati en vue de leur modelisation informatique,

civil, Paris, 28–29 Novembre 1988. ´Rapport de recherche IRIN no. 172, Universite de Nantes,´[24] A. Dupagne, J. Teller, Representation de l’espace ouvert 1998, 31 p.

` ´dans un systeme d’information de projet urbain, Ingenierie`des systemes d’information 5 (1997) 219–239.

playing with design intents: integrating physical and urban constraints in cad

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