Hofmann, Georg Rainer2015-10-052015-10-0519891017-4656https://doi.org/10.2312/egtp.19891012The measuring of natural objects like landscapes and already existing (not simply planned!) buildings produces natural data. That data of hue geometry typically consists of Non-planar Polygons. These may be triangulized, but the results are unfortunately: - a large increase of the number of polygons, - texture mapping becomes more complicated, - facetting effects in the rendered image. This paper addresses methods and algorithms of the direct rendering of Non-planar Polygons. Special "texture mapping" is presented to insert especially Photographic Components in Non-planar Polygons to obtain naturalistic images. With Photographic Components, a very simple illumination model is sufficient to obtain good results in rendering quality. Further on an application example is presented. The images of this example are outstanding both for their naturalism and the little computer CPU time spent for their rendering. Basics on naturalism and photorealism in Computer Graphics are discussed.10.2312/egtp.19891012