Pose Transfer And Topology Optimization Of Mesh Models

Shape editing and topology optimization of mesh models are fundamental operations in digital geometry processing. Shape editing techniques can make it convenient for users to cre-ate new shape and pose, while the quality of meshes has a great impact on all kinds of mesh manipulations. This thesis conducts research on these two aspects of mesh processing.In shape editing, example-based modeling is an important technique for reusing models and is widely utilized in geometric and shape design. Deformation transfer and pose transfer, which fall into the category of such techniques, take use of reference meshes to drive a source mesh into deforming. Different from deformation transfer, pose transfer only accepts one reference model as pose indication. The difficulty of representing a pose makes pose transfer challenging. On the other hand, it is difficult to improve the quality of a quad mesh due to the specificity of quad mesh structure in which a small modification in topology might lead to structure change of a large region. The context of the thesis and our main contributions are as follows.1) Details-preserving spectral pose transfer. We propose a new pose transfer method which combines Laplace coordinates editing and pose transferring based on low frequency coef-ficients of the Laplace matrix of mesh models together in a nonlinear deformation energy. Observing that optimizing the aforementioned energy leads to a dense linear system, we inte-grate the cage-based subspace technique into the framework. This not only greatly improves the computational efficiency but also enhances the stability of solutions due to deforming degree of freedoms being reduced.2) Hierarchical pose transfer framework. Revealing the multi-scale property of the pose of a 3D model, we devise a simple hierarchical strategy to transfer the different-scale poses of the reference model onto the source one progressively.3) Helix strip generation algorithm for quad mesh optimization. The structure of a quad mesh is negatively affected by the number of its helix strips, and removing these helix strip-s may greatly improve the topological quality of the mesh. We systematically analyze the properties of irregular vertices and the relationships between helix strips and irregular ver-tices. Based on the analysis, we devise a general algorithm for searching helix strips in quad meshes. Experiments show that it is capable of effectively finding helix strips and optimizing the topology of complex quad meshes.