Realistic Hair Rendering In Renderman

Due to the rapid development of the industry of films and animations, technology of photo-realistic rendering in computer graphics has been widely carried out. In the early years of the development of Computer Graphics, limited by computer hardware conditions, photo-realistic rendering did not get enough attention. Later, due to the rapid development of computer hardware and software, realism had gradually become the main objective pursued by the film and animation producers. The realism of roles in films and animations is not only depended on the realism of the skin and the eyes, but also the realism of the hair. In another word, the realism of rendered hair partly determined the realism of the role in film and animation.In the existing commercial film and animation producing pipeline, hair of the role is usually modeled by Maya Hair or Shave and a Haircut, and rendered by certain render engine. Due to the lack of hair rendering of our Renderman-compliant renderer-Bleman, and in order to meet the functional requirements of commercial rendering engine, we added a module to our renderer for hair export and rendering.Based on the existing system framework, we introduced several ways to achieve the goal of hair rendering. Three ways could be used for Maya Hair rendering and two ways could be used for Shave Hair. We also analyzed the merits and faults of each method, and gave the experimental result.In our work, we found a issue named Near-field hair rendering-when the camera is near to the hair, the render result of hair will be looked like ribbons. For this case, we introduced a solution named Fake Normal to solve the problem. At the same time, we also introduced a photo-realistic Shader to our rendering engine. What’s more, the Shader could be used for Maya Hair rendering without changing any parameter or model of original scenes.As a result of our work, Bleman supports models of different hair style in Maya. In the end of this article, we compared the rendering results of our renderer with the results of a commercial Renderman renderer-3Delight, and gave the analysis of the results. The results show that our work can meet the need of hair rendering in commercial films and animations.