a Department of Architecture, Building and
Planning, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The
b VDO Car Communication, Navigation Lab. Eindhoven, Glaslaan 2, 5616 LW Eindhoven, The Netherlands
Most traditional CAD systems developed from 2D drawing systems to 3D drawing systems, lacking appropriate tools for 3D design. One would expect a 3D architectural design system to have a 3D-design environment with knowledge about the designed entities. Such a 3D-design environment supports the creation and manipulation of 3D shapes. The design environment should essentially be 3D as opposite to the well-known Windows environment with its menu-structured interface. Navigating and manipulating in 3D requires 3D geometrical primitives, but also a set of 3D design tools.
This paper presents the results of a research project that aimed the use of geometric constraints for support of architectural design. A set of constraint types was defined to express explicit and implicit geometric relations between building elements. A constraint satisfaction technique based on Linear Programming was introduced to achieve that the design support system responds in accordance with the users' expectations. To examine and demonstrate the application of geometric constraints in a 3D environment two prototype systems were developed. Simple experiments with the prototype systems indicate that the proposed design constraints serve the design operations as expected.
Developing design systems raises questions about user access to geometry data. There seems to be a trade off between having a complete and consistent set of design data and allowing a designer to freely edit geometry. The underlying question however is how user interaction with the design at the building element description level should be communicated with the geometries at the drawing primitives level. In this respect the prototype systems demonstrate the application of geometric constraints for the support high level design operations while maintaining consistency of the geometrical representation.