Research And Application Of Range Image Registration And Surface Subdivision

During the past decade, as the progress of computer hardware technology, the research on three dimensional imaging and modeling (3DIM) has been increasingly active while the applications of 3DIM have also appeared popular ever since. This tendency attributes to the fast development in the field of optical engineering, computer science and technology, as well as the microelectronics technology. Nowadays, 3DIM has gradually changed our daily life ranging from traditional manufacturing industry to preservation of historical heritages. The contents of this thesis addresses two key issues involved in three dimensional imaging and modeling, namely, range image registration and surface subdivision. The research on them as well as on the application of 3DIM is meaningful in both theory and practice.Range image registration is one of the key issues in three dimensional imaging and modeling. It aims to find out the rigid transformations of all range images captured from different viewpoints and then bring them into a common coordinate system, i.e. the world coordinate system. However, the most popular registration method, ICP algorithm, is always suffered from two serious problems: initial pose estimation and noise outliers. Therefore, we present a new concept, Surface Mean Inter-Space Measure, in this thesis for the first time in order to assist accurate registration. On the basis of the new measure we have fulfilled the registrations under two different frames, ICP and GA, respectively. The experimental results illustrate that the proposed measure is more robust than the point-corresponding method. And it's more insensitive to noises as well as more precise in measuring the quality of registration results.The second key issue to be addressed is the subdivision surface, which is an effective tool for fitting the three dimensional scattered data. Subdivision surface can be used to solve the problems such as the smoothness, precision, and level of detail modeling as well. However, there is still a constraint in conventional subdivision techniques. For example, it is hard for them to preserve the sharp features in original models. The scheme now used in most existing surface fitting systems is the Loop method modified by Hoppe. With a 1-4 split operator, this scheme would achieve limited level of details. In order to overcome this limitation, we develop a new approach that improve the rules of 3^2/1 subdivision and reconstruct the piecewise smooth surfaces. The continuity of modified subdivision surface is also analyzed. The results indicate that the presented method can introduce more levels of details and provide a better quality of fitting surfaces.The third part of this thesis involves realistic 3D facial modeling. The fast development of 3DIM brings more techniques and applications for realistic 3D facial modeling. So in this part, we present a new method for this purpose. The proposed method makes use of two orthogonal photographs and a generic facial model to reconstruct photo-realistic 3D facial models. The free-form deformation and mesh simplification are incorporated with the subdivision techniques to construct a new method to build the geometric models. At the same time, a new face detection algorithm based on fuzzy pattern matching and a new facial feature contour extraction method based on a modified color Snake model and some morphological edge detectors are presented to provide individual facial information. Both of them are necessary for realistic 3D facial modeling.