Real-time human model design

This thesis describes a flexible human geometric model useful for human factor studies. The model offers a solution for aligning the skeletal system with the surface geometry of the human form while maintaining computational efficiency. Most of the existing models implement surface modeling techniques. Since most of the joints in human body are not on the surface, it is difficult to embed the joint position in surface models. This makes the alignment between geometry and the skeletal system difficult. In our model, we choose free-form deformations, a volume modeling technique. We also perform segmentation to improve the computational efficiency. In reality, the geometric deformation for joints connecting short segments such as the torso and neck is different from that for free appendages such as arms and legs. Therefore, we propose different schemes to handle the two types of deformations. In simulating free appendages, each joint is inspected separately. For joints with multi degrees of freedom, we separate the twisting degrees of freedom of the joints from the bending degrees of freedom because they deform different regions. We handle joints connecting short segments by group. Each joint group is associated with one single control mesh. The number of nodes involved in each group joint is usually large. Therefore, we use a two-phase control scheme to handle the group joint. The first phase aligns the joint orientations and approximates the joint positions. The second phase clarifies the joint locations. For some implementations, we can bypass the second step to improve the computational efficiency