The basic reqirement for the functions of an Iterated Function System (IFS for shor) is contractivity. Nevertheless the majority of recent scientific investigations is concentrating on IFSs defined through a set of contractive linear functions. Simpler handling of this kind of functions and a more predictable results is the main reason for this approach. In this work we use distorted grids (representing nonlinear functions) to specify an IFS with a higher degree of flexibility and a higher modeling capability. A program for modeling these grids with so-called high-level operations is presented. Attention is directed to the interactivity of designing the IFS and rendering its limit set. Therefore a z-Buffer for displaying the result of a stochastic algorithm is included. Example images designed with the implemented software system are presented
