Coarse Registration of Surface Patches with Local Symmetries

Most 3D recording methods generate multiple partial reconstructions that must be integrated to form a complete model. The coarse registration step roughly aligns the parts with each other. Several methods for coarse registration have been developed that are based on matching points between different parts. These methods look for interest points and use a point signature that encodes the local surface geometry to find corresponding points. We developed a technique that is complementary to these methods. Local descriptions can fail or can be highly inefficient when the surfaces contain local symmetries. In stead of discarding these regions, we introduce a method that first uses the Gaussian image to detect planar, cylindrical and conical regions and uses this information to compute the rigid motion between the patches. For combining the information from multiple regions to a single solution, we use a a Hough space that accumulates votes for candidate transformations. Due to their symmetry, they update a subspace of parameter space in stead of a single bin. Experiments on real range data from different views of the same object show that the method can find the rigid motion to put the patches in the same coordinates system.