Research Of Real Time Shadow Rendering Algorithm

Recent advances in Graphics technology have produced a shift in focus for real time rendering application, which includes Interactive 3D graphics modeling programs, virtual reality and 3D simulation system, computer animation, games and so on. Regarding graphics demonstration quality, a higher request was put forward in addition to display more triangles as quickly as possible. The rapidly evolution of graphics display card and GPU technology make many new rendering effect were Widespread used, such as anti-aliasing, motion blur and real time shadow technology. The shadow effect has play an important role in the generation of photorealistic image as well as the judgment of objects related position, Although many mature shadow generation algorithms have been used successfully in computer games, animation and virtual reality systems,In the dynamic scenes ,rending a realistic soft shadow in real time is a huge challenge.Shadow algorithms can be used to determine the surfaces which can be seen from the light source, the surfaces which are not visible to the light source are out of shadow, While the surfaces which are visible to the light source are in the shadow. Because of the mutual occlude ring of different objects, the shadow region's shape and size are depended on objects shape, mutual relation of position, the shape and size of the light source. To a 3D scene, shadow have great three-dimension performance ability. First, they help understand relative object placementin a 3D scene by providing visual cues. Second, they dramatically improve image realism and allow the creation of complex lighting ambiance. The rapidly development of modern hardware make the bring up and realization of new shadow generation algorithm possible. But most of the popular algorithms or satisfy the rendering rate of real time, or complement precise shadow effect. there are no soft shadow algorithm can generate precise shadow effect while rendering in real time. Our paper concludes most of the different algorithms and discusses the advantages and disadvantages, limitation, quality, and the order of the complexity, Then put forward a new real time soft shadow rendering algorithm, It can not only compute the precise boundary of the shadow, but also rendering the shadow in real time, it can deal with most of the systems which need high real time performance. At last, we prospect the development direction of real time soft shadow ,then bring up some directions which worthy to research of real time soft shadow.The content and contribution of our research can be summarized into the following four phases:1.We put forward a new algorithm to compute soft shadow of convex polyhedra rapidly.2.We put forward a rapidly and precisely shadow algorithm for point light source.3.We put forward a new soft shadow algorithm for sphere light source which can not only compute precise boundary of shadow but also can satisfy the request of real time rendering.4.In the view of the point cloud model which be more and more popular, we first put forward a effiency algorithm to computer the shadow for point cloud model.