Use of a Building Database in Prediction of Three-dimensional Diffraction

This paper describes 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. The storage format of buildings in a geographi_c information systems database is described. An algorithm is presented for identifying the nearest diffracting building and d~riving the necessary information for the evaluation of the diffraction integral. Example results are presented to show the utility of this approach.