Viewer-centered geometric feature recognition

Computer aided design (CAD) and computer aided manufacturing (CAM) systems are now indispensable tools for all stages of product development. The flexibility and ease of use of these systems has dramatically increased productivity and quality of product while reducing lead times. These advances have been largely achieved by automating individual tasks. At present, these islands of automation are poorly linked. One reason for this is that current computer systems are unable to extract geometric and topological information automatically from solid models that is relevant to the down-stream application. In other words, feature information. The objective of the research reported in this paper was to develop a more generic methodology than heretofore, in order to find the generic protrusion and depression features of a CAD model. The approach taken is one relying on a more human type of analysis, one that is "viewer-centered" as opposed to the object-centered approach of most previous research in this area. The viewer-centered approach to feature recognition described is based on a novel geometric probing or tomographic methodology. A five-step algorithm is described and then applied to a number of components by way of illustration.