Computer Graphics Building Definition System
Authors: Jeffrey Z. Gingerich
Venue: Proceedings of the 10th Design Automation Workshop (1973)

In the Architectural field many computer programs exist for design aid. They vary from space allocation algorithms to structural analysis and computer graphic design. More often than not, these programs are independent. Even though most of the architectural programs use similar data in describing buildings and/or parts of buildings and its systems, they very seldom have compatible formats. Therefore, to run a program the user must redescribe the building and/or its parts. If a firm, college, or the profession (preferably) defines a workable building definition data base for use in all programs, one can see there would be a time and work advantage. A workable data base would by definition have to be flexible enough to handle input, output, and change. It should be inclusive enough to define any and all parts down to the level necessary for the building's final construction. Just having a workable building data base would be ineffective without a powerful language to feed and retrieve the building data. When realizing this, one wonders what to develop first, the data base or the language. The approach of this study was to develop a prototype language using computer graphics. The Computer Graphics Building Definition (CGBD) System is designed with the following ideas: 1) computer graphics input and output to simulate the conventional architectural drafting language; 2) the data base prototype as a module to insure compatibility when a more sophisticated base is designed. The goal is a first step system that will allow for future change and addition. The CGBD System facilitates describing a building in an interactive set of two phases. Phase I is schematics. Here the designer lays out areas (interior and exterior) of the building which he wants to analyze or he is currently designing. (As with the conventional drafting language, design and definition can be one.) This is accomplished using the cathode-ray tube and light pen instead of paper and drafting equipment. The user defines the building (s), two-dimensionally, one level (or floor) at a time. Building area modules can be created, repeated, or manipulated and floors repeated or displayed for tracing and reference. These techniques increase the speed of the building definition process. Erasing areas, parts of areas, or buildings is also available to increase the user's efficiency. Phase II is a three-dimensional inspection package that allows the defined parts of the building to be displayed. The building may be rotated about any of the three axes as an orthographic or perspective projection. Hidden line removal can be used for viewing the building masses as a solid or may be suppressed to view interior floor or interior area configurations. The viewpoint for perspective projection can be adjusted. Scissoring and enlarging are available for closer inspection of building parts. By using the speed of a computer to simulate drafting, sketching, and visual inspection, the user can define and/or design buildings while simultaneously providing a building data base for use in other design programs.