Research On Geometric Calculation And Deformation Of 3D Craniofacial Model

Craniofacial measurements have been widely employed in many fields, including the anthropology, anatomy, clinical medicine, forensic medicine, medical equipment design, national security, human identification, biomedical engineering and others. At the same time, how to make full use of the results acquired from the measurements of the three-dimensional (3D) human face models, as well as how to do fine-tuning to those models—to provide a direct and efficient way for deformation and re-edition by users, hence to change the 3D models conveniently, has been an important focus and goal for the Computer-Aided Geometric Design and Graphics (CG & CAGD) research.The Anthropologic theory on the relevance between skull and face is the theoretical foundation of this research. Aided by the computer visualization technology, the characteristics of the skull and face are studied and the 3D geometric characteristics of the skull are computed scientifically. Based on these results, the 3D face model is deformed and re-edited with the constraint of the geometric features of the skull.The main research includes:1) Study on the geometric characteristics of the skull and face. Based on the analysis of all the definitions on the skull and face features in and abroad, it sets up the elements of the geometric contents of the computer-aided measurement of the skull and face. And the study in this thesis is also under the guidance of the theories on plastic surgery and aesthetics.2) The reconstruction of the 3D face model. The computer 3D visualization technology is employed in the reconstruction of the 3D surface and volume of the original computed tomography (CT) slices. A mesh simplification algorithm is proposed based on the feature points of the 3D face. Experiment results show that this algorithm is significantly simplified and the characteristics of the skull and face are maintained.3) 3D calculation. Based on the analysis of the 3D interactive technology and the 3D space picking algorithm, it gives out the methods in calculating the distance, angles, area, volume, and other geometric parameters of the 3D face model.4) Deformation and edition of the 3D face model. A 3D model for interactive editing and deforming is carried out based on the 3D calculations. By employing the improved algorithm of point constrained deformation for mesh deformation, a nicer deformation on nose is received. Mesh deformation with hierarchical B-splines is implemented in the end.5) The design and implementation of the 3D calculation and the mesh deformation system "SkullComEditor". This system is functional in 3D reconstruction and simplification, 3D calculation and mesh deforming and editing. And it is also valuable in craniofacial morphology.This research work is supported by National Natural Science Foundation ofChina(60736008).