Recognizing the construction methods of (piecewise) polynomial or rational curves and surfaces are of great importance, e.g., for geometrical data exchange between two different modeling systems. Project aims to find conditions that would determine geometric shape of object from set of input curves and surfaces. These conditions should be able to detect: (1) whether a curve segment is a line, a circle, a circular arc or a planar curve; (2) whether a surface patch is a plane, a cylinder or a cone; and (3) whether a surface is constructed as a surface of revolution, a extrusion, a ruled/developed surface or a generalized cylinder. The detected geometric features could be added to CAD systems using their native CAD APIs. This would be achieved by choosing appropriate model parameters and creation method. In this way, we can reconstruct the geometry as it was in original. Input is received in the form of IGES files through comprehensive IGES Reader programs developed to process input geometric model. ukryj opis