Michio Shiraishi

Cyber Tai Chi - CG-based Video Materials for Tai Chi Chuan Self-Study

Tai Chi Chuan is a popular Chinese martial art, practiced all over the world. Practitioners have to memorize complicated forms of motion, which is the first hurdle for beginners. We applied CG and VR technologies to self-study video materials and demonstrated that these cyber technologies can improve practices of this traditional martial art.

Rendering Translucent Materials with Plane-parallel Solution

Lighting simulation is very important in realistic image synthesis, and the simulation of subsurface scattering has recently attracted much attention. Although the dipole/multipole model has succeeded in creating realistic images, it is still difficult to deal with volumetric features in subsurface scattering, which is important when rendering optically thin objects. This paper proposes a novel rendering method that utilizes the plane-parallel solution and the ray-marching method. The ray-marching method has been used to calculate single scattering solutions, and the plane-parallel solution has been adopted to calculate BRDFs. By combining these techniques, the proposed method efficiently captures volumetric features in multiple subsurface scattering events. In our experiments, the proposed method demonstrated a performance superior to that of previous methods in terms of accuracy.

Real-time rendering of dynamic clouds

This paper presents a fast cloud rendering method for dynamic scenes, where cloud shapes and lighting environments dynamically change. Although the Harris method [Harris and Lastra 2001] has been widely used for static cloud rendering, it can be fatally slow for real-time applications when, for example, light directions change. By introducing the 3D attenuation buffer and re-arranging the algorithm, we improved the rendering speeds of dynamic clouds by a factor of 10--100 times. The image quality is also improved due to a finer representation of light distribution.

Multiple scattering approximation in heterogeneous media by narrow beam distributions

Fast realistic rendering of objects in scattering media is still a challenging topic in computer graphics. In presence of participating media, a light beam is repeatedly scattered by media particles, changing direction and getting spread out. Explicitly evaluating this beam distribution would enable efficient simulation of multiple scattering events without involving costly stochastic methods. Narrow beam theory provides explicit equations that approximate light propagation in a narrow incident beam. Based on this theory, we propose a closed‐form distribution function for scattered beams. We successfully apply it to the image synthesis of scenes in which scattering occurs, and show that our proposed estimation method is more accurate than those based on the Wentzel‐Kramers‐Brillouin (WKB) theory.

A Simplified Plane-parallel Scattering Model for Rendering Densely Distributed Objects such as Foliage

Fast computation of multiple reflections and scattering among complex objects is very important in photorealistic rendering. This paper applies the plane-parallel scattering theory to the rendering of densely distributed objects such as trees. We propose a simplified plane-parallel scattering model that has very simple analytic solutions, allowing efficient evaluation of multiple scattering. A geometric compensation method is also introduced to cope with the infinite plane condition, required by the plane-parallel model. The scattering model was successfully applied to tree rendering. Comparison with a Monte Carlo method was made and reasonable agreement was confirmed. A rendering system based on the model was implemented and multiple inter-reflections were effectively obtained. The view-independent feature of the model allows fast display of scenes. The pre-computation is also modest, permitting interactive control of lighting conditions.