Use of a building database in prediction of three-dimensional diffraction

The use of a building database and a three-dimensional formulation of the Fresnel-Kirchoff diffraction theory to compute the shadowing by buildings in the general situation where diffraction can occur by building edges of both horizontal and vertical orientation is described. The storage format of buildings in a geographic information system database is described. An algorithm for identifying the nearest diffracting building and deriving the necessary information for the evaluation of the diffraction integral is presented. Example results are presented to show the utility of this approach