Research Of Real-time Soft Shadow Rendering Technology

Shadow plays an important role in 3D virtual scene. First, the shadow can help us understand complex geometric information about receiver; Secondly, the shadow can help us understand the size and location of the relationship of objects in 3D space; Finally, the shadow will help us understand geometric shapes of occluder. Therefore, how to generate real-time and realistic shadows for 3D virtual scene is very important.With the development of computer graphics, people to improve the realistic of computer generated graphics.At this time, soft shadows arises at the historic moment. There is no doubt to soft shadows in the role of realistic, but it has also brought a new challenge real-time. So, computer graphics bounded in thinking about how to keep the premise of real-time performance in improving graphic realism? From perspective existing soft shadows generation algorithms, there are many improved strategy, but there are still some problems. Some algorithm cannot generate self-shadows, Some algorithm restrict the type of occluder and receiver, Some algorithm ignore light's size and shape and some algorithm just formed inside the penumbra at penumbra or the penumbra, and so on.Along with the computer graphics processing unit (GPU) to appear, In order to generate more vivid, lifelike scenes, The hardware manufacturers directly support shadow rendering in its graphics processing unit. All this, providing broader research space in 3D virtual scene to generate high quality of the shadow.Shadow volumes consumed large time in dealing with large scene, reduced the algorithm efficiency, can not reach the requirement of real-time. Although Shadow mapping algorithm better than shadow volumes algorithm in real-time, its realistic is bad. Because it produces the hard shadows.In computer graphics real-time and realistic contradiction. This thesis forward rendering fake soft shadows based on the erosion and dila-tion. We improve the classic shadow mapping algorithm and it does not reduce frame rate. Still using twice rendering, but with classic shadow mapping algorithm is different. We operate expands outward and inward corrosion in the second times before rendering to get the new shadow figure, finally render the scene. In addition, in order to improve the real-time, we fully utilize the programmable graphics processor parallel computing capabilities, explore accelerate scheme, improve GPU effici-ency, enhancement algorithm real-time.Experiments showed the proposed algorithm can produce realistic soft shadow and has certain anti-aliasing function. Although this method is not the precise calculation based on physics, it simulates the soft shadow to generate more realism fake soft shadows and can be applied to form soft shadows in a large scale in 3D situations. So this algorithm has huge application prospect.