Research Of An Algorithm Of Real-time Shadow Rendering Based On Shadow Map Anti-aliasing

The shadow exists in the real world, it will be appeared where the light and objects, it is an indispensable part in the real world. Realistic and real-time shadow rendering technology in computer graphics and image processing,3D animation video,3D games and many other aspects of computer simulation has played a significant role and has been widely used. But realistic and real-time rendering of the shadow is a contradiction problem, and it is an important puzzle must be solved.Shadow realistic problem was mainly due to the generated shadow will produce jagged aliasing, which is caused by insufficient shadow map sampling, if the higher resolution of the shadow map is, the smaller jagged aliasing problem shadow produce, however, to solve the realistic problem of shadow by increase the resolution of the shadow map is not realistic, because the texture cache space is very limited, and it will also affect the real-time shadow rendering. Shadow real-time problem was mainly due to the generated shadow need a great lot of calculation which make shadow rendering speed difficult to reach per second 15 frames, it can not attach the minimum requirements for real-time.Through the research of shadow rendering techniques at home and abroad, the real-time shadow rendering technique can be divided into two categories:shadow map algorithm and shadow volume algorithm. They have both advantages and disadvantages. Shadow Map algorithm is simple and can attach real-time shadow rendering, but the shadow which is generated has the phenomenon of aliasing, making the formation of the shadow is not enough real; Shadow Volume algorithm can generate correct and clear shadow, but it will consumpt a large fill rate and needs a greate lot of calculation, it will need a long time to render shadow, so it is not reach a real-time. The problem on aliasing of shadow map and slow rendering of shadow volume, This paper gives an algorithm of real-time rendering shadow based on image space and object space by combination of shadow map algorithm and shadow volume algorithm, firstly, this algorithm makes use of Shadow Map algorithm based on image space to determine the shadow boundary region and render the non-shadow boundary region, and then using Shadow Volume algorithm based on object space to render the shadow boundary region, it not only solves shadow aliasing problem generated by shadow map algorithm, but also realizes real-time rendering shadow in the scene. In addition, this paper proposes a method using NURBS curve to generate the outline edge of the shadow in order to fleetly achieve a clear shadow boundary. A large of experiments prove the algorithm can make shadow generated to meet the requirements of realism and real-time in the three-dimensional virtual scene.