The Research Of Sub-pixel Hard Shadow Anti-aliasing Technique

Shadowscan help to improve the reality of the virtual scene and the user's immersion,the realistic rendering technology of shadow has become the main research of computer graphics.At present,there are three main ways to render real-time shadows: ray tracing algorithm,shadow volume algorithm and shadow map algorithm.Among them,the shadow map algorithm is the main method of rendering the real-time hard shadow,and it is the most widely used methodcurrently.A new sub-pixel shadow map algorithm based on deep extrapolation(DESM)is proposed to solve the aliasingproblem of shadow map algorithm.Thealgorithm improved the accuracy of sub-pixel shadow by optimizing the formula of depth derivation;In order to solve the shadow defect caused by the information of incomplete geometry,the algorithm used depth extrapolation detection method to estimate the depth value of pixels.The experimental results showed that the algorithm is suitable for hard shadow rendering of the simple primitives.A sub-pixel shadow map algorithm based on anti-aliasing filtering(AFSM)is proposed for the hard shadow rendering of fine primitives or complex geometric primitives.Firstly,the relevant geometrical information is stored tightly to reduce the memory consumption.Then,the irrelevant shadow samples are eliminated by the anti-aliasing filtering technique,and the subpixel shadows are reconstructed by interpolating the relevant samples.At last,we used the idea of morphological estimation to fuse the completely separated sub-pixels.Experiments showed that the sub-pixel shadow map algorithm based on anti-aliasing can repair more shadow details and get more accurate shadow silhouette.