Spatial constraints in collaborative design processes

User requirements, building codes, construction rules and regulations imply constraints on a building design. Additional constraints are introduced by the different participants of the collaborative planning process through the individual body of knowledge representing their particular domain. Checking digital building models for compliance with these constraints allows detecting design errors and conflicts in an early stage. To realize this, all constraints have to be represented in a computer-processable form. However, many regulations and codes make use of higher spatial concepts, such as “must contain”, “must be above”. Today, such constraints can only be implemented by software experts using advanced geometry algorithms. In order to facilitate the definition of spatial constraints for common users, the paper introduces the concept of providing predefined metric, directional and topological operators as ready-made building blocks. The paper discusses in detail a proposed extension of the IFC constraint framework to include these spatial operators and describes procedures for embedding spatial constraint checks in the collaborative planning process.