A Repartition Structure for Collision Detection and Deformation of Discrete Objects Based on 3D Wavelets

In a virtual sculpture project, we would like to sculpt in real-time 3D objects sampled in volume elements (voxels). The drawback of this kind of representation is that a very huge number of voxels is required to represent large and detailed objects. Consequently, the memory cost will be very large and the user/object interaction will be slowed down. We proposed a multiresolution representation of 3D objects thanks to a 3D wavelet transform, in order to reduce the memory cost and to adapt the processing and display times with a desired level of detail. In order to allow real-time performance during the sculpting process, we propose in this paper a repartition structure, which is an octree whose each node contains maximal and minimal density for each area of the 3D object. Moreover, we combine this structure with a multiresolution collision detection, to accelerate the sculpting process during the addition and subtraction of matter into the 3D object thanks to a tool, both with the same multiresolution representation.