3d digital geometric reconstruction of the urban environment fot daylighting simulation studies

In principal, the algorithms used in advanced lighting simulation software are equally applicable to interior and exterior situations [Ashdown 1994][Ward 1998]. In practice the scope is limited: a realistic CAD model of a building in a complex urban geometry can have two/three orders of magnitude more data elements than a detailed model of a room. This is reflected in the computer power needed and, significantly, in the time required for the collection and input of data. These factors, in turn, determine the usefulness of the computation within the design process and place limits on the stages in which it can be incorporated. This paper examines the techniques available at the present time that can be used to aid the collection, recording, design and reconstruction of 3D Model Geometry for use in Computer Daylighting Simulation.