Yoshiaki Usami

A simple method for extracting the natural beauty of hair

A simple differential equation method is proposed for modeling the aesthetic features of human hair. In the method, a simplified cantilever beam simulation is employed for hairstyle modeling, which allows hairdressing variations with volumetric and realistic appearance. In order to describe the dynamical behavior of hair in an animation, one-dimensional projective differential equations of angular momenta for linked rigid sticks are also derived. For the problem of collision detection between hair and a human head, the “rough” approximate solution is provided, which gives visually satisfactory results by solving the projective equations under a ps~udo-force field. The hair’s pliability can be controlled by using a set of stiffness parameters in the method. In addition, a fast rendering technique for anisotropic reflection is introduced, which is derived from Blirm’s specular model. The efficiency of the proposed method is illustrated by the still images and short animations obtained. CR

A practical method of constructing surfaces in three-dimensional digitized space

We propose a new, practical algorithm for constructing the surface of a three-dimensional object from its planar cross-sections. This algorithm deals with a general case where each cross-section of the object is given as a two-dimensional digital image and no topological information about these two adjacent cross-sections is assumed. In particular, it can handle the case where there are several connected components with some holes in each cross-section. The algorithms principle is derived from the “region growing” technique. which is well-known in two-dimensional image processing. By combining this algorithm with existing shading techniques, we can obtain a realistic image of a three-dimensional object.