Cumincad : CUMINCAD Papers : Search Results

CumInCAD is a Cumulative Index about publications in Computer Aided Architectural Design
supported by the sibling associations ACADIA, CAADRIA, eCAADe, SIGraDi, ASCAAD and CAAD futures

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_id	a6f1
authors	Bridges, A.H.
year	1986
title	Any Progress in Systematic Design?
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 5-15
summary	In order to discuss this question it is necessary to reflect awhile on design methods in general. The usual categorization discusses 'generations' of design methods, but Levy (1981) proposes an alternative approach. He identifies five paradigm shifts during the course of the twentieth century which have influenced design methods debate. The first paradigm shift was achieved by 1920, when concern with industrial arts could be seen to have replaced concern with craftsmanship. The second shift, occurring in the early 1930s, resulted in the conception of a design profession. The third happened in the 1950s, when the design methods debate emerged; the fourth took place around 1970 and saw the establishment of 'design research'. Now, in the 1980s, we are going through the fifth paradigm shift, associated with the adoption of a holistic approach to design theory and with the emergence of the concept of design ideology. A major point in Levy's paper was the observation that most of these paradigm shifts were associated with radical social reforms or political upheavals. For instance, we may associate concern about public participation with the 1970s shift and the possible use (or misuse) of knowledge, information and power with the 1980s shift. What has emerged, however, from the work of colleagues engaged since the 1970s in attempting to underpin the practice of design with a coherent body of design theory is increasing evidence of the fundamental nature of a person's engagement with the design activity. This includes evidence of the existence of two distinctive modes of thought, one of which can be described as cognitive modelling and the other which can be described as rational thinking. Cognitive modelling is imagining, seeing in the mind's eye. Rational thinking is linguistic thinking, engaging in a form of internal debate. Cognitive modelling is externalized through action, and through the construction of external representations, especially drawings. Rational thinking is externalized through verbal language and, more formally, through mathematical and scientific notations. Cognitive modelling is analogic, presentational, holistic, integrative and based upon pattern recognition and pattern manipulation. Rational thinking is digital, sequential, analytical, explicatory and based upon categorization and logical inference. There is some relationship between the evidence for two distinctive modes of thought and the evidence of specialization in cerebral hemispheres (Cross, 1984). Design methods have tended to focus upon the rational aspects of design and have, therefore, neglected the cognitive aspects. By recognizing that there are peculiar 'designerly' ways of thinking combining both types of thought process used to perceive, construct and comprehend design representations mentally and then transform them into an external manifestation current work in design theory is promising at last to have some relevance to design practice.
series	CAAD Futures
email
last changed	2003/11/21 15:16

_id	876b
authors	Christiansson, Per
year	1986
title	Structuring a Learning Building Design System
source	Advancing Building Technology, CIB International Congress (10th : 1986 : Washington D. C.). 9 p. : ill. includes bibliography
summary	It is now vital to aim at formulating computer system modules that possess a high ability to adapt their behavior to fundamental human values and a complex and unstandardized (not uniform) building process but at the same time put constraints on them so that we don't end up with a confusion of computerized routines hard to access, control and understand. In the paper formulations are made of basic artifact skeletons outgoing from the properties to give integrated CAD systems and to those rules by which the growth of the systems are governed. System learning domains including conceptual modelling tools are presented aiming at supporting professional skill, creativity and integration between process actors. The basis for system implementation is frames, descriptive language (PROLOG) and relational databases with regard taken to future possibilities to parallel processing
keywords	modeling, learning, integration, database, AI, design, systems, frames
series	CADline
last changed	1999/02/12 15:07

_id	896b
authors	Haider, Jawaid
year	1986
title	A Conceptual Framework for Communication -Instruction in Architectural Design
source	Pennsylvania State University
summary	Existing design models, it is generally acknowledged, are inadequate to deal with the complexity of contemporary situations; and an assessment of self-conscious design manifests a slow development in the power and scope of conceptualizing. The quality of knowledge and conceptual tools available to the designer largely determine his ability to conceive and accomplish; conversely, the limitations of method are reflected in design solutions. Some emerging social problem-solving paradigms, which seek to construct a cognitive psychology of problem solving, have a direct relevance to architectural design. Notwithstanding the traditional criticism and scepticism, problem solving is predicated by task environment and problem space as these have a significant impact on design synthesis. Despite a rigorous search for theoretical perspectives and methods, the concern for the quality of the physical environment persists unabated. Historically, architecture has depended on other disciplines for its theoretical insight; but the application of borrowed theories without a viable framework for translation has often resulted in misinterpretation. Aggravating the problem is the art-science controversy which has consequences for architectural practice and education. What is required is a unified approach encompassing the scientific and artistic modes of inquiry. But a unified perspective, involving vast and disparate areas of human knowledge, demands a conceptual framework for integrative learning. The proposed model of this study provides such a framework and calls for a re-examination of the conventional boundaries of design disciplines. It advocates an interdisciplinary approach and recognizes the design process as inherently a learning process; this shifts the emphasis from product to process and allows students to plan and assess their own design/learning experience. While the study focuses on substantive issues, it identifies a strategy for integrative learning applicable within the existing context of design education. Despite its untested nature, the proposed model can become a vehicle for stimulating coordination of all facets of human knowledge and experience toward creative design synthesis. It inculcates a sense of critical assessment of generative ideas by presenting a conceptually clearer picture of the design process to elicit a response to and a better understanding of the task environment of architecture.
series	thesis:PhD
email
last changed	2003/02/12 22:37

_id	aad7
authors	Mackenzie, C.A. and Gero, John S.
year	1986
title	Learning in the Domain of Decisions and Performances
source	IAAI'86 Conference. 1986. pp. i:1:1-9. CADLINE has abstract only
summary	Many domains present themselves as mappings between two classes of spaces: decision spaces and performance spaces. All design domains can be represented in this manner where the designer takes decisions which manifest themselves as performances in the designed artifact. Learning in these domains can take account of the structural characteristics of the spaces and of the mappings. This paper describes a system, PARE, which learns in the domain of decisions and performances by making use of the characteristics of a particular structuring concept known as 'Pareto optimality.' Much is known about the concept and its features which are used as hypotheses. If the hypotheses succeed then learning takes place by specializing the hypotheses' characteristics. Characterizations of Pareto optimality are described and the feature extraction process shown. The feature extraction process utilizes fuzzy pattern matching. An example of the system, written in ConSUN workstations, is presented from the domain of fenestration design
keywords	performance, learning, design process, optimization, analysis, applications, theory, systems
series	CADline
email
last changed	2003/06/02 13:58

_id	7a08
authors	Smith Shaw, Doris
year	1986
title	Case Studies in Architectural CADD Education
doi	https://doi.org/10.52842/conf.acadia.1986.157
source	ACADIA Workshop ‘86 Proceedings - Houston (Texas - USA) 24-26 October 1986, pp. 157-172
summary	Stages in the formation of concepts necessary for mastery can be observed in cognitive development in many different areas of study. These stages seem to follow a particular hierarchy common to most learners. Distinct levels can be recognized by patterns of procedural errors. The remediation of errors can then take the form of building a conceptual framework rather than training in procedural patterns. This has been found to be highly efficient for learners at all stages since it can be aimed at the underlying problem area and not at isolated errors which may change frequently. It was felt, that concept development of architects learning to use computer-aided drawing programs would show such levels. Preliminary studies made at the U.S. Army Construction Engineering Research Laboratory upon selected subjects using computer-aided lessons in AutoCAD as a basis for observations reveal several categories of errors in using computer-aided design. These case studies show that the design process can be enhanced by automated drawing and design tools if the conceptual relationships are established as a part of the learning environment. Even more important, the observations show that architects have particular characteristics which differ from engineers and other CAD users. These differences require that education and software be tailored to their needs.
series	ACADIA
last changed	2022/06/07 07:56

_id	69c7
authors	Woodbury, Robert F.
year	1986
title	VEGA : A Geometric Modelling System
source	11 p. : ill. Engineering Design Research Center, CMU, April 1986. DRC-48-03-87. includes bibliography
summary	VEGA is a program which models rigid solid objects in three dimensions. Specifically, its domain is assemblies of planar faced polyhedra. VEGA supports a variety of operations to create, modify, query and delete these assemblies. VEGA is intended to serve two purposes: that of a new medium of representation for the design process; and of a programming package to support geometric applications in a wide variety of domains. Here the author addresses primarily the first of these purposes, that of a new medium for design. Designers of physical objects use an external medium, traditionally paper or physical models, not only to record their work, but to provide information which assists in the understanding of implications of design decisions. Designers proceed by performing operations, which reflect internal design decisions, on this external medium. The operations used in design are generally reflective of these physical media. For example, models built of clay tend to be formed by a subtractive processes, whereas models built of wood tend to be additive in nature. Designers who use drawings as their medium still tend to use operations which reflect operations on physical models. Computers provide the fascinating potential to provide a much wider variety of operations at a much greater speed than is available with the traditional means of representation. In addition, a computer based representation can provide quantitative information not easily accessible from traditional forms. This opens the potential for the inclusion of formal means of evaluation in the design process; something which is generally almost absent in traditional design teaching. A computer program which effectively and 'naturally' models physical objects and operations on them would be a valuable assistance to both the teaching and practice design. VEGA has been designed with these objectives in mind. VEGA represents physical objects with a scheme known as boundary representation and provides a wide variety of operations on these objects. VEGA also provides means to associate other, non-geometric, information with the objects it represents. VEGA is implemented under the ANDREW system. It communicates to ANDREW through a graphics package, also developed by the author's group. VEGA is intended to serve as a medium for future studio courses in the Architecture, Industrial Design and Arts education
keywords	geometric modeling, solid modeling, CAD, education, assemblies, B-rep, systems
series	CADline
email
last changed	2003/06/02 10:24

_id	63d0
authors	Carrara, Gianfranco and Novembri, Gabriele
year	1986
title	Constraint-bounded design search
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 146-157
summary	The design process requires continual checking of the consistency of design choices against given sets of goals that have been fulfilled. Such a check is generally performed by comparing abstract representations of design goals with these of the sought real building objects (RBO) resulting from complex intellectual activities closely related to the designer's culture and to the environment in which he operates. In this chapter we define a possible formalization of such representations concerning the goals and the RBO that are usually considered in the architectural design process by our culture in our environment. The representation of design goals is performed by expressing their objective aspects (requirements) and by defining their allowable values (performance specifications). The resulting system of requirements defines the set of allowable solutions and infers an abstract representation of the sought building objects (BO) that consists of the set of characteristics (attributes and relations) which are considered relevant to represent the particular kind of RBO with respect to the consistency check with design goals. The values related to such characteristics define the performances of the RBO while their set establishes its behaviour. Generally speaking, there is no single real object corresponding to an abstract representation but the whole class of the RBO that are equivalent with respect to the values assumed by the considered characteristics. The more we increase the number of these, as well as their specifications, the smaller the class becomes until it coincides with a single real object - given that the assessed specifications be fully consistent. On the other hand, the corresponding representation evolves to the total prefiguration of the RBO. It is not therefore possible to completely define a BO representation in advance since this is inferred by the considered goals and is itself a result of the design process. What can only be established in advance is that any set of characteristics assumed to represent any RBO consists of hierarchic, topological, geometrical and functional relations among the parts of the object at any level of aggregation (from components to space units, to building units, to the whole building) that we define representation structure (RS). Consequently the RS may be thought as the elementary structures that, by superposition and interaction, set up the abstract representation that best fit with design goals.
series	CAAD Futures
last changed	1999/04/03 17:58

_id	c898
authors	Gero, John S.
year	1986
title	An Overview of Knowledge Engineering and its Relevance to CAAD
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 107-119
summary	Computer-aided architectural design (CAAD) has come to mean a number of often disparate activities. These can be placed into one of two categories: using the computer as a drafting and, to a lesser extent, modelling system; and using it as a design medium. The distinction between the two categories is often blurred. Using the computer as a drafting and modelling tool relies on computing notions concerned with representing objects and structures numerically and with ideas of computer programs as procedural algorithms. Similar notions underly the use of computers as a design medium. We shall return to these later. Clearly, all computer programs contain knowledge, whether methodological knowledge about processes or knowledge about structural relationships in models or databases. However, this knowledge is so intertwined with the procedural representation within the program that it can no longer be seen or found. Architecture is concerned with much more than numerical descriptions of buildings. It is concerned with concepts, ideas, judgement and experience. All these appear to be outside the realm of traditional computing. Yet architects discoursing use models of buildings largely unrelated to either numerical descriptions or procedural representations. They make use of knowledge - about objects, events and processes - and make nonprocedural (declarative) statements that can only be described symbolically. The limits of traditional computing are the limits of traditional computer-aided design systems, namely, that it is unable directly to represent and manipulate declarative, nonalgorithmic, knowledge or to perform symbolic reasoning. Developments in artificial intelligence have opened up ways of increasing the applicability of computers by acquiring and representing knowledge in computable forms. These approaches supplement rather than supplant existing uses of computers. They begin to allow the explicit representations of human knowledge. The remainder of this chapter provides a brief introduction to this field and describes, through applications, its relevance to computer- aided architectural design.
series	CAAD Futures
email
last changed	2003/05/16 20:58

_id	6105
authors	Rasdorf, William J. and Fenves, Stephen J.
year	1986
title	Constraint Enforcement in a Structural Design Database
source	Journal of the Structural Division. American Society of Civil Engineers, December, 1986. vol. 112: pp. 2565-2577
summary	During the design of a commercial structure, large amounts of information pertaining to all aspects of the design must be stored, accessed, and operated upon. A database management system (DBMS), composed of a central repository of data and the associated software for controlling accesses to it, provides one way to generate, represent, manage, and use this information. However, DBMSs are not presently structured in such a way that they can flexibly represent complex engineering constraint relationships, including those defined by codes, standards, and specifications. This paper examines structural design constraints and addresses the question of how they can be incorporated into DBMSs. It presents four representations of engineering constraints: the text of a design specification, the equations extracted from the specification, the dependency network among the constrained data items, and a relational DBMS model. The database model was implemented using a commercially available DBMS and the limitations of the implementation are explored. What is new in this DBMS model is that a constraint dependency subnetwork is associated directly with the stored data that it constrains. The implemented result is a new abstraction, consisting of a relation and a set of computations and checks, that enforces the relationships embodied in the dependency network. The database user need only initially define a set of rules and computed attributes. These are then used by the DBMS to automatically perform the appropriate checks and assignments. The database user is, to a significant degree, free of constraint checking concerns because the system itself knows what to do
keywords	constraints management, civil engineering, database, DBMS
series	CADline
last changed	2003/06/02 13:58

_id	a91c
authors	Meyer, G., Rushmeier, H., Cohen, M., Greenberg, D. and Torrace, K.
year	1986
title	An Experimental Evaluation of Computer Graphics Imagery
source	ACM Transactions on Graphics, 5, No. 1
summary	Accurate simulation of light propagation within an environment and perceptually based imaging techniques are necessary for the creation of realistic images. A physical experiment that verifies the simulation of reflected light intensities for diffuse environments was conducted. Measurements of radiant energy flux densities are compared with predictions using the radiosity method for those physical environments. By using color science procedures the results of the light model simulation are then transformed to produce a color television image. The final image compares favorably with the original physical model. The experiment indicates that, when the physical model and the simulation were viewed through a view camera, subjects could not distinguish between them. The results and comparison of both test procedures are presented within this paper.
series	journal paper
last changed	2003/04/23 15:50

_id	a7de
authors	Bic, Lubomir and Jonathan P. Gilbert
year	1986
title	Learning from AI : New Trends in Database Technology
source	IEEE Computer. March, 1986. vol. 19: pp. 44-54. includes bibliography
summary	With the steadily increasing demand for user-oriented systems, new trends in database technology have evolved outside of the scope of the traditional data models. The authors are concentrated in this article on two closely related efforts: The incorporation of more semantic modeling capabilities into database models, and the development of better user environment, which include user friendly interfaces and support different user views of the content and organization of the data
keywords	AI, user interface, database, relational database
series	CADline
last changed	1999/02/12 15:07

_id	0565
authors	Oxman, Robert and Oxman, Rivka
year	1990
title	The Computability of Architectural Knowledge
source	The Electronic Design Studio: Architectural Knowledge and Media in the Computer Era [CAAD Futures ‘89 Conference Proceedings / ISBN 0-262-13254-0] Cambridge (Massachusetts / USA), 1989, pp. 171-185
summary	In an important contribution to the theoretical foundation of design computing, Mitchell noted "an increasingly urgent need to establish a demonstrably sound, comprehensive, rigorously formalized theoretical foundation upon which to base practical software development efforts" (Mitchell, 1986). In this paper we propose such a theoretical framework. A basic assumption of this work is that the advancement of design computing is dependent upon the emergence of a rigorous formulation of knowledge in design. We present a model of knowledge in architectural design which suggests a promising conceptual basis for dealing with knowledge in computer-aided design systems. We require models which can represent the formal knowledge and manipulative operations of the designer in all of their complexity-that is formal models rather than just geometric models. Shape Grammars (Stiny,1980) represent an example of such models, and constitute a relatively high level of design knowledge as compared to, for example, use of symmetry operations to generate simple formal configurations. Building upon an understanding of the classes of design knowledge as the conceptual basis for formal modeling systems may contribute a new realization of the potential of the medium for design. This will require a comprehensive approach to the definition of architectural and design knowledge. We consider here the implications of a well-defined body of architectural and design knowledge for design education and the potential mutual interaction-in a knowledge-rich environment-of design learning and CAAD learning. The computational factors connected with the representation of design knowledge and its integration in design systems are among the key problems of CAAD. Mitchell's model of knowledge in design incorporates formal knowledge in a comprehensive, multi-level, hierarchical structure in which types of knowledge are correlated with computational concepts. In the main focus of this paper we present a structured, multi-level model of design knowledge which we discuss with respect to current architectural theoretical considerations. Finally, we analyze the computational and educational relevance of such models.
series	CAAD Futures
email
last changed	2003/05/16 20:58

_id	6cfe
authors	Wagter, H.
year	1986
title	A New Generation Needs New Tools (A Proposal for a Joint Effort)
doi	https://doi.org/10.52842/conf.ecaade.1986.323
source	Teaching and Research Experience with CAAD [4th eCAADe Conference Proceedings] Rome (Italy) 11-13 September 1986, pp. 323-327
summary	After an introduction describing the present situation on computer- programs used in learning environments, some remarks are made on what future programs should look like. Although the design and the building process are both extremely complex, a proposal is made to carry out a project in a joint effort among ECAADE members to achieve a new generation of learning tools. These tools should also be of good service in a consulting environment.
series	eCAADe
email
last changed	2022/06/07 07:58

_id	40fe
authors	Gero, John S., Oxman, Rivka E. and Manago, C.
year	1986
title	Graphics and Expert Systems
source	AUSGRAPH '86 Australian Conference on Computer Graphics (4th : 1986 : Sydney). pp. 25-29 : ill. includes bibliography
summary	Expert systems are a novel software technology which aim to model the behavior and knowledge of human experts. This paper presents two modes of interaction between graphics and expert systems in the domain of computer-aided design. The first concerns the interaction between an expert system and commercial CAD systems. The second demonstrates how expert systems can control design oriented graphical representations. Examples from both modes are presented from systems developed at Sydney University
keywords	computer graphics, expert systems, CAD, architecture
series	CADline
email
last changed	2003/06/02 10:24

_id	5509
authors	Koutamanis, Alexandros
year	1990
title	Development of a computerized handbook of architectural plans
source	Delft University of Technology
summary	The dissertation investigates an approach to the development of visual / spatial computer representations for architectural purposes through the development of the computerized handbook of architectural plans (chap), a knowledge-based computer system capable of recognizing the metric properties of architectural plans. This investigation can be summarized as an introduction of computer vision to the computerization of architectural representations: chap represents an attempt to automate recognition of the most essential among conventional architectural drawings, floor plans. The system accepts as input digitized images of architectural plans and recognizes their spatial primitives (locations) and their spatial articulation on a variety of abstraction levels. The final output of chap is a description of the plan in terms of the grouping formations detected in its spatial articulation. The overall structure of the description is based on an analysis of its conformity to the formal rules of its “stylistic” context (which in the initial version of chap is classical architecture). Chapter 1 suggests that the poor performance of computerized architectural drawing and design systems is among others evidence of the necessity to computerize visual / spatial architectural representations. A recognition system such as chap offers comprehensive means for the investigation of a methodology for the development and use of such representations. Chapter 2 describes a fundamental task of chap: recognition of the position and shape of locations, the atomic parts of the description of an architectural plan in chap. This operation represents the final and most significant part of the first stage in processing an image input in machine environment. Chapter 3 moves to the next significant problem, recognition of the spatial arrangement of locations in an architectural plan, that is, recognition of grouping relationships that determine the subdivision of a plan into parts. In the absence of systematic and exhaustive typologic studies of classical architecture that would allow us to define a repertory of the location group types possible in classical architectural plans, Chapter 3 follows a bottom-up approach based on grouping relationships derived from elementary architectural knowledge and formalized with assistance from Gestalt theory and its antecedents. The grouping process described in Chapter 3 corresponds both in purpose and in structure to the derivation of a description of an image in computer vision [Marr 1982]. Chapter 4 investigates the well-formedness of the description of a classical architectural plan in an analytical manner: each relevant level (or sublevel) of the classical canon according to Tzonis & Lefaivre [1986] is transformed into a single group of criteria of well-formedness which is investigated independently. The hierarchical structure of the classical canon determines the coordination of these criteria into a sequence of cognitive filters which progressively analyses the correspondence of the descriptions derived as in Chapter 3 to the constraints of the canon. The methodology and techniques presented in the dissertation are primarily considered with respect to chap, a specific recognition system. The resulting specification of chap gives a measure of the use of such a system within the context of a computerized collection of architectural precedents and also presents several extensions to other areas of architecture. Although these extensions are not considered as verifiable claims, Chapter 5 describes some of their implications, including on the role of architectural drawing in computerized design systems, on architectural typologies, and on the nature and structure of generative systems in architecture.
series	thesis:PhD
email
last changed	2003/02/12 22:37

_id	cc1a
authors	Lien, Kristian, Go Suzuki and Westerberg, Arthur W.
year	1986
title	The Role of Expert Systems Technology In Design
source	[2] 49 p. : diagrams Engineering Design Research Center, CMU, September, 1986 EDRC-06-13-86. includes bibliography.
summary	Using a scenario format, this paper first reviews the nature of chemical process design, showing that designers quickly make major decisions with minimal information and constantly revise their strategy to solve a problem. To automate this activity on a computer will require models of the process being created at several levels of abstraction as well as models that capture the beliefs of the modeler about the abilities of himself, others and the aids available and models of strategies for complex problem solving. The second section of the paper extensively reviews current expert system concepts, illustrating each of them with design examples. It is argued that expert systems are knowledge based. The authors describe many of the control strategies used in today's systems, and also consider different problem representations - rules, logic and frames - and indicate when each might be preferred. The last section presents the authors views on what will be involved in creating a future expert system for design
keywords	engineering, abstraction, expert systems, CAD, design process, representation, knowledge base, frames, control
series	CADline
last changed	2003/06/02 10:24

_id	c92d
authors	Sederberg, Thomas W. and Goldman, Ronald N.
year	1986
title	Algebraic Geometry for Computer-Aided Geometric Design
source	IEEE Computer Graphics and Applications. June, 1986. vol. 6: pp. 52-59
summary	An object description associating a tolerance with each of its topological features (vertices, edges, and faces) is introduced. The use of tolerances leads to a definition of topological consistency that is readily applied to boundary representations. The implications of using tolerances to aid in making consistent topological determinations from imprecise geometric data are explored and applied to the calculations of a polyhedral solid modeler
keywords	Algorithms; Curves; Computational Geometry; Mathematics; Education; Intersection
series	CADline
last changed	2003/06/02 10:24

_id	47c5
authors	Weiler, Kevin J.
year	1986
title	Topological Structures for Geometric Modeling
source	Computer and Systems Engineering, Rensselaer Polytechnic Institute
summary	Geometric modeling technology for representing three-dimensional objects has progressed from early wireframe representations, through surface representations, to the most recent representation, solid modeling. Each of these forms has many possible representations. The boundary representation technique, where the surfaces, edges, and vertices of objects are represented explicitly, has found particularly wide application. Many of the more sophisticated versions of boundary representations explicitly store topological information about the positional relationships among surfaces, edges, and vertices. This thesis places emphasis on the use of topological information about the shape being modeled to provide a framework for geometric modeling boundary representations and their implementations, while placing little constraint on the actual geometric surface representations used. The major thrusts of the thesis fall into two areas of geometric modeling. First, a theoretical basis for two-manifold solid modeling boundary topology representation is developed. The minimum theoretical and minimum practical topological adjacency information required for the unambiguous topological representation of manifold solid objects is determined. This provides a basis for checking the correctness of existing and proposed representations. The correctness of the winged edge structure is also explored, and several new representations which have advantages over existing techniques are described and their sufficiency verified. Second, a non-two-manifold boundary geometric modeling topology representation is developed which allows the unified and simultaneous representation of wireframe, surface, and solid modeling forms, while featuring a representable range beyond what is achievable in any of the previous modeling forms. In addition to exterior surface features, interior features can be modeled, and non-manifold features can be represented directly. A new data structure, the Radial Edge structure, which provides access to all topological adjacencies in a non-manifold boundary representation, is described and its completeness is verified. A general set of non-manifold topology manipulation operators is also described which is independent of a specific data structure and is useful for insulating higher levels of geometric modeling functionality from the specifics and complexities of underlying data structures. The coordination of geometric and topological information in a geometric modeling system is also discussed.
series	thesis:MSc
last changed	2003/02/12 22:37

_id	04dd
authors	Zozaya-Gorostiza and Hendrickson, Carlos and Chris
year	1986
title	A Network Representation and Algorithm for Task Planning
source	23 p. : ill Pittsburgh, PA: Engineering Design Research Center CMU, December, 1986. EDRC-12-08-87. includes bibliography.
summary	An activity planning algorithm based on a network representations of conditions and actions is presented. The algorithm performs backward expansions on each desired condition in order to express them as a combination of initial conditions and actions. A global problem network of actions and conditions is used to represent the history of successful conditions expansions. This representation maintains consistency and improves the efficiency of search procedure. Interpretation of this problem network leads to an actions network from which feasible plans are directly obtained. The network algorithm was implemented in LISP and is applied here to solve blockworld problems similar to those found in the artificial intelligence planning literature. However, the algorithm and the network representation are general and intended to be used as an analytical tool in planning systems that formulate sequences of multiple actions
keywords	algorithms, planning, networks, representation, AI
series	CADline
last changed	2003/06/02 13:58

_id	678e
authors	Aish, Robert
year	1986
title	Three-dimensional Input and Visualization
source	Computer-Aided Architectural Design Futures [CAAD Futures Conference Proceedings / ISBN 0-408-05300-3] Delft (The Netherlands), 18-19 September 1985, pp. 68-84
summary	The aim of this chapter is to investigate techniques by which man-computer interaction could be improved, specifically in the context of architectural applications of CAD. In this application the object being designed is often an assembly of defined components. Even if the building is not actually fabricated from such components, it is usually conceptualized in these terms. In a conventional graphics- based CAD system these components are usually represented by graphical icons which are displayed on the graphics screen and arranged by the user. The system described here consists of three- dimensional modelling elements which the user physically assembles to form his design. Unlike conventional architectural models which are static (i.e. cannot be changed by the users) and passive (i.e. cannot be read by a CAD system), this model is both 'user generated' and 'machine readable'. The user can create, edit and view the model by simple, natural modelling activities and without the need to learn complex operating commands often associated with CAD systems. In particular, the user can view the model, altering his viewpoint and focus of attention in a completely natural way. Conventional computer graphics within an associated CAD system are used to represent the detailed geometry which the different three-dimensional icons may represent. In addition, computer graphics are also used to present the output of the performance attributes of the objects being modelled. In the architectural application described in this chapter an energy- balance evaluation is displayed for a building designed using the modelling device. While this system is not intended to offer a completely free-form input facility it can be considered to be a specialist man-machine interface of particular relevance to architects or engineers.
series	CAAD Futures
email
last changed	2003/11/21 15:15

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