Interactive modeling system for relief-like objects by using virtual chisels and design sketches

Presents a relief modeling system in a virtual space. Since relief-like objects are basically shaved from one direction, we describe the objects as 2.5-dimensional shapes by using polygon-meshed height maps. This data description is simple, so that the objects can be easily modified. Our system offers a user interface which is similar to real relief modeling. Users can engrave various ditches on object surfaces by dragging virtual chisels. Tools that cut out primitive shapes from relief objects are also available. A design sketch is a binary image where a user draws the contour lines of a planed object. The image is used to select a closed area in order to pull it up or down in a single operation. This image is needed to mask object surfaces, and a gray-scale image is also available for creating a small relief mold. Since the height map cannot represent overhangs along slant edges, shades and shadows around those edges are not correctly displayed. We add edge attributes at each polygon vertex for rendering such edge effects