This study investigated the implementation of a hand model and contact simulation method for the purpose of improving the reality of object manipulation in a virtual environment. The study focused both on the hand tracking method that takes advantage of nails and also contact simulation using a deformable hand model. The manipulation of an object using a hand, is known to make more frequent use of the fingertips and palm. The proposed method seeks hand form that minimizes the position and orientation errors on those areas. Deformation of the soft tissue of the hand is considered to have an effect on both visual reality and the physical state of contact. In our implementation, the deformation was simulated by FEM and the friction of contact was introduced by the penalty method. In addition, a model that is based on metaballs (or blobs) was employed to represent the smooth surface of the object and to eliminate the problem that derives from polygon modeling. Through experimental implementation, it was proved that object manipulation such as pinching and grasping are possible and that the update rate of simulation can be approximately 50 Hz.

We propose a novel approach to haptic interact with complex inhomogeneous elastic objects like organs. In surgery simulations, representation of complex inhomogeneous elastic objects which have various physical properties and geometries is required. Also, consideration of geometric nonlinearity is required. At present, in order to simulate such objects correctly, we have to use the nonlinear FEM model with high resolution meshes. Furthermore, higher update rate (about from several hundred [Hz]) is required for stable force feedback. Therefore, computational cost becomes problem. In this paper, to solve this problem, we propose an adaptive and embedded deformation model. This approach uses both an online re-mesh deformation model and a corotational FEM model together. Our approach can update an inverse of a global stiffness matrix of a corotational FEM model quickly during the online remeshing (tetrahedron subdivision/simplification). In addition, an efficient computation algorithm by GPU is also proposed. We implemented this approach into our prototype surgery simulation system, and then we performed evaluation experiments to verify the feasibility and effectiveness of our approach.

We have developed a novel automultiscopic display, CAGRA (Computer-Aided Graphical Real-world Avatar), which can provide full parallax both horizontally and vertically without imposing any other additional equipment such as goggles on users. CAGRA adopts two axes of rotation so that it can distribute reflected light all around. In our previous work, it was proved that the display can present a black and white image of a 3D object at 1 Hz with both horizontal and vertical parallax. Here, we discuss two important problems that remain unsolved in our previous work: optimal parameter setting and the rendering method. As for finding optimal parameters, the relationship among the rotation speed of two axes and the diffusion angle of the holographic diffuser is discussed. The rendering method was implemented so that accurate view is presented in spite of the unique mechanical structure of CAGRA. Furthermore, the synchronization mechanism between projection of images and rotation of the mirror, which was also a remaining problem, is also implemented. Findings obtained through solving these problems clarify the characteristics of this novel display system, CAGRA, and lead to its further development.

This paper discusses the implementation of an automultiscopic omni-directional display. By rotating a flat-panel display whose viewing angle is strictly limited, or has sharp directivity, different and independent views are presented to different viewpoints. Design parameters including the resolution of viewpoints and update rate for viewers are clarified, and the effect of the refresh rate of display panels, speed of rotation, directivity of the panel on these parameters are discussed. Based on the discussion; the implementation of a prototype is reported. A directional filter using lenticular and slit array is devised, and its characteristic is evaluated. Also, a rendering algorithm that takes into account the effect of rotation of the display panel is proposed. Through experiments the feasibility of the proposed approach is confirmed.