Surface roughness is a key parameter for determining the quality of machined parts. A graphical model for the calculation of quantitative data affecting surface roughness of machined surfaces was developed. The model allows the determination of the accurate machined surface in cloud of points form retrieved from the visualization system buffer in a three dimensional graphics environment developed in OPENGL . Critical quantitative parameters for surface roughness, such as , and mean line, are determined from this topomorphy. The results together with the operations are visualized in a virtual machine shop environment developed in a commercial development toolkit.