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CumInCAD is a Cumulative Index about publications in Computer Aided Architectural Design
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_id	4104
authors	Ervin, Stephen McTee
year	1989
title	The structure and function of diagrams in environmental design :a computational inquiry
source	Massachusetts Institute of Technology
summary	The design process often begins with a graphical description of the proposed device or system and sketching is the physical expression of the design engineer's thinking process. Computer Aided Design is a technique in which man and machine are blended into a problem solving team, intimately coupling the best characteristics of each. Solid modelling is developed to act as the common medium between man and the computer. At present it is achieved mainly by designing with volumes and hence does not leave much room for sketching input, the traditional physical expression of the thinking process of the design engineer. This thesis describes a method of accepting isometric free hand sketching as the input to a solid model. The design engineer is allowed to make a sketch on top of a digitizer indicating (i) visible lines; (ii) hidden lines; (iii) construction lines; (iv) centre lines; (v) erased lines; and (vi) redundant lines as the input. The computer then processes this sketch by identifying the line segments, fitting the best possible lines, removing the erased lines, ignoring the redundant lines and finally merging the hidden lines and visible lines to form the lines in the solid in an interactive manner. The program then uses these lines and the information about the three dimensional origin of the object and produces three dimensional information such as the faces, loops, holes, rings, edges and vertices which are sufficient to build a solid model. This is achieved in the following manner. The points in the sketch are first written into a file. The computer than reads this file, breaks the group of points into sub-groups belonging to individual line segments, fits the best lines and identify the vertices in two dimensions. These improved lines in two dimensions are then merged to form the lines and vertices in the solid. These lines are then used together with the three dimensional origin (or any other point) to produce the wireframe model in three dimensions. The loops in the wireframe models are then identified and surface equations are fitted to these loops. Finally all the necessary inputs to build a B-rep solid model are produced.
series	thesis:PhD
email
last changed	2003/02/12 22:37

_id	0f73
authors	Ervin, Stephen M.
year	1990
title	Designing with Diagrams: A Role for Computing in Design Education and Exploration
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. 107-122
summary	Environmental designers, design educators and design students using computers are a constituency with a set of requirements for database structure and flexibility, for knowledge representation and inference mechanisms, and for both graphical and non-graphical operations, that are now articulatable and to-date largely unmet. This is especially so in the area called 'preliminary' or 'schematic' design, where our requirements are related to, but different from, those of our colleagues in mechanical and electrical engineering, whose needs have dominated the notable developments in this area. One manifestation of these needs is in the peculiar form of graphics called diagrams , and the ways in which environmental designers (architects, landscape architects., urban designers) use them. Our diagrams are both similar to and different from structural, circuit, or logical diagrams in important ways. These similarities and differences yield basic insights into designing and design knowledge, and provide guidance for some necessary steps in the development of the next generation of CAD systems. Diagrams as a form of knowledge representation have received little scrutiny in the literature of graphic representation and computer graphics. In the following sections I present an overview of the theoretical basis for distinguishing and using diagrams; examine some of the computational requirements for a system of computer-aided diagramming; describe a prototype implementation called CBD (Constraint Based Diagrammer) and illustrate one example of its use; and speculate on the implications and potential applications of these ideas in computer-aided design education.
series	CAAD Futures
last changed	1999/04/03 17:58

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