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PDF papers
id ddss9459
authors Langelaan, Willem
year 1994
title Sequential and Concurrent Cad Layering
source Second Design and Decision Support Systems in Architecture & Urban Planning (Vaals, the Netherlands), August 15-19, 1994
summary Most CAD software allows graphical and text objects to be grouped into layers. There are two fundamentally different methods for layering: sequential layering and concurrent layering. With sequential layering, layers are attributes of the CAD database and objects are attributes of a layer. With concurrent layering, objects are attributes of the CAD database and a layer is an attribute of an object. Sequential layering emulates the pinbar drafting technique. As a result, it is output oriented. Only one layer at a time can be edited. Concurrent layering is uniquely a computer based layering method which has no manual equivalent. User specified sets of layers can be edited concurrently. It makes it possible to organize the infrastructure of the CAD database which equally facilitates input, i.e. editing design information, and output, i.e. presenting construction information on paper. Specification levels are related to design levels and to construction phases. Specification levels can serve as interfaces between input and output. In particular, a concurrently layered CAD database can be structured in layers which conform to specification levels. Furthermore, the layers can be subdivided by sub-system such as construction discipline, and by partial-system such as room finish schedules. It is demonstrated how a concurrently layered environment for computer aided design can be developed which permits deductive and inductive design activities. The appendix provides a detailed example of a concurrently layered CAD file with a default input and output environment of layers and layer groups. The environment was developed to coordinate the design and production activities of an architectural practice. The connections between layers and layer groups are illustrated in a 22 x 32 matrix.
series DDSS
references Content-type: text/plain
last changed 2003/08/07 14:36