1. A process for the generation of a computer image of a coated, three-dimensional object comprising the steps of, in appropriate order: a) preparing a coating comprising a relevant coating layer with variable layer thickness on at least one test panel, b) taking a plurality of measurements of at least one optical surface property as a function of the layer thickness of the relevant coating layer, c) storing the optical data in a datafile with assignment of the layer thickness of the relevant coating layer, d) facetting the visible surfaces of a three-dimensional object by computer into a sufficient number of flat polygonal areas each being sufficiently small for the sufficiently accurate description of the surface topography, e) assigning layer thickness of the relevant coating layer and associated optical data in each case to each individual polygonal area by computer, and f) assembling the polygonal areas into a computer image of the three-dimensional object.