However, most acquired 3D models, whether created by hand or by using automatic tools, contain errors and inconsistencies. Solid modeling information is rarely available. Rather, polygon soup seems to be the rule.
Problems arise from many sources, including designer errors or software errors in the modeling tool.
Currently, techniques to reconstruct manifold models from acquired 3D models are not very robust. Other approaches based on merging features within some tolerance of each other do not work well when the size of errors are larger than the smallest feature in the model. In this case, no suitable tolerance can be chosen that both fills cracks and preserves small features. The system partitions space into convex polyhedral regions separated by planes supporting the input polygons. Once solid regions have been identified, the system can output consistent solid model and boundary representations without intersecting, coplanar, or unconnected polygons.