Physically-Based Subsurface Scattering Simulating

With the development of technology to enhance the graphics and computing capabilities, photorealistic rendering technology in film and television animation, video games, simulation and other areas more widely. Material highly realistic rendering an important role in the whole process, as the current mainstream PRman, Arnold and other film-commercial renderer has its own material system, the artist by combining a variety of materials and adjust their parameters, you can use The renderer of photorealistic images, and ultimately these stunning pictures made into a movie is presented to the audience.Business renderer provided material can be divided into two categories, which can be used to simulate the basic material of glass, plastic, stainless steel and other hard surfaces as difficult to achieve low and early development has matured, and like the skin of this particular have subsurface scattering characteristics of the material because of the difficulty of achieving high and late development has been an important factor to judge the merits of a photorealistic renderer. On the other hand, since all organisms have a non-conductive subsurface scattering characteristics, so the application of this material in the film and the game is very extensive.The use of pure physical simulation of subsurface scattering material because convergence is too slow and can not practice, then approximate simulation of subsurface scattering materials have come into being. However, these approximation methods have advantages and disadvantages, and some fast rendering complex process but the general effect, and some simple effects of class but the rendering process is slow, and the current research on the real-time sub-surface scattering of small, Xu Quintilian only way out Objects can be applied to the case of constant light conditions.Paper studies two different subsurface scattering algorithms and renderman renderer specification as a platform on how to achieve sub-surface scattering material in-depth study in the class renderer, finally give a complete implementation, and The experimental results were compared and analyzed. Then, combined with the previous method, proposed subsurface scattering algorithm for real-time GPU-based, which is divided into two steps, the first step in the use of sampling methods BSSRDF importance sampling point texture coordinates of each point depends coloring and they are stored in the map, while the second step is calculated for each colored dot, according to the texture coordinates obtained in the previous step will direct light surface are fused to obtain colored spot color.The main work of this paper are:1, based on rapid hierarchical point cloud surface scattering, the point cloud to implement this method in architecture REYES renderer optimized distribution when combined with multi-level surface scattering algorithm, surface roughness of a quick minute with level surface scattering algorithm that can simulate smooth jade.2 presents a realization BSSRDF importance sampling subsurface scattering algorithm-based approach, we propose a simple and efficient method for constructing BVH tree lighting and scene Intersection in renderman renderer specification, and the reactor before rendering Ray and quadrilateral Intersection algorithm is improved.3, a new importance by BSSRDF sampling points precomputed and stored in a way that maps based on real-time GPU subsurface scattering algorithm, which for the first time allows the illumination of objects can be changed in real time environment.