In this paper we propose a tool that compares the difference of the surface and its simplified representation. Geometry-based metrics usually cannot truly reflect how the user perceives the difference when surfaces are rendered on the screen, hence we provide an alternative tool that is image-based, which complement the deficiency of the geometry-based. Two metrics are implemented in the tool: ...

Abstract Dynamic Geometry Software (DGS) includes packages such as Cabri Géomètre (also available in the Texas Instruments' TI-92), the Geometer's Sketchpad and Thales, for PC and Mac. These enable users to define objects such as points, lines (or segments, rays and vectors) and circles (or arcs) and to construct geometric objects depending on them by classical constructions (straight edge and ...