Subdivision-Based Space Deformation Method And Generation Of Control Meshes

Space deformation is an effective tool for shape modification in geometric modeling system and flexible motion in computer animation system. However, it's not an easy work to perform intuitive interaction by using the conventional free-form deformation methods, because of either inconvenient control tools or large time and space costs.A new interactive space deformation method based on subdivision surface is proposed in this paper. First, a control mesh is defined according to the object shape. The control mesh can possess arbitrary topology. Then it is refined by subdivision methods such as Doo-Sabin subdivision, Loop subdivision, Modified Butterfly subdivision etc. The subdivision surface of control mesh and its normal will span an intermediate deformation space. Its function is similar with the parametric volume in Free-Form Deformation method. The object to be deformed will be attached to the control mesh through the closest rule. By remaining the local coordinates of the object in the intermediate deformation space unchanged, the deformation of the control mesh will pass to the object. In the proposed deformation method, the shape of the object can be edited either locally or globally by selecting different resolution of the refined control mesh. Compared with the previous object deformation methods, the proposed method has advantages of intuitive and fast interaction.How to generate the control mesh which follows the object shape is one of the key problems to achieve intuitive object deformation or editing. A space deformation system is realized based on the proposed deformation method. In our system, arbitrary topological control mesh, which has the same topology and similar shape with the object, can be automatically generated. Here Reeb graph is utilized as the auxiliary tool during the generation of the control mesh. Furthermore, our system supplies many interactive editing tools for generating control meshes in the system, such as primitive meshes, rotational mesh, sweeping mesh, 3D Boolean operation, mesh extrusion and so on. Moreover, our system can achieve multi-resolution deformation control, thus can sculpt fine features on the object.