Computer-aided building often relates to complex designed objects such as hospital buildings. The design image comprises initially an overall formal description and later a unique assembly of many separate 3D elements. The 3D design description used here for buildings accommodates both forms of description simultaneously. The level of description required for each is, however, not necessarily fully detailed. This paper outlines the approach tahen by A RC (Applied Research of Cambridge) to modelling large-scale, multiple-element assemblies that make up building designs. These techniques are employed in the BDS (Building Design Systems) supplied and supported by ARC.
Three-dimensional descriptions are central to many techniques in computer-aided design. ARC has been particularly interested in solving the problems that arise in the building field. The extent of our interest has been the design and description of large complex buildings such as hospitals, in which spaces can be multiclassified and whose design results in the assembly of very large numbers of individual components.
Computer-aided design and production techniques can be classified according to three degrees of complexity 1
β’ complexity of individual elements β’ number of elements in the design objects β’ level of integration required in the design and production processes
The first two use the mechanisms of geometrical description; the third is determined by the required scope of the overall application.
DATA STRUCTURES FOR BUILDING DESCRIPTION
In its work in computer-aided building, ARC has developed techniques and data structures for building descriptions which reflect different stages in the building design process. At early stages in building design the user is likely to be manipulating spaces and developing their specifications. Later, as more detailed work proceeds, the design requires the handling of individually located parts. The description of the individual parts themselves is of limited complexity, but they hold references to additional specification information.
The functions of 3D box geometry which are employed in the building description are outlined: