A Generic Shadow Map Method for Generating Shadows

Abstract

The invention discloses an auxiliary technology for generating shadows from a general shadow map, including: pre-calculating the contour line template to obtain a contour line sampling point lookup table; drawing the scene from the light source space, and combining the shadow map algorithm based on uniform point sampling to form a linear Shadow map; draw the scene from the viewing space, transform the pixels to the light source space, and classify the pixels into contour pixels and non-contour pixels; use linear interpolation to calculate the depth of the occluder for the non-contour pixels, and compare the depth values ​​​​to get the shadow result ; For the contour line pixels, the contour line sampling points are read in the pre-built contour line sampling point lookup table through the local similarity relationship, and the shadow result is obtained according to the positional relationship between the pixel coordinates and the contour line sampling points. The invention provides an auxiliary technology for generating shadows from shadow maps. On the basis of existing shadow map algorithms, the shadow generation quality or algorithm performance of these algorithms is improved with less additional performance overhead.

Description

Technical field [0001] The invention relates to the field of computer graphics shadow drawing, in particular to a method for generating shadows from a general shadow map. Background technique [0002] Shadow is one of the important elements of the real world, and it is also an indispensable part of the realistic rendering of synthetic images. It carries important information such as the position of the light source and the direction of light transmission in the scene. Although the shadow drawing algorithm has been a classic problem in computer graphics, the problem of how to generate shadows efficiently and robustly has not been completely solved. The two mainstream algorithms for drawing shadows are the shadow map algorithm and the shadow volume algorithm, which represent two hard shadow generation ideas based on image and geometry respectively. The biggest feature of the shadow map algorithm is simple and efficient, and the performance of the algorithm is basically independen...

AI Technical Summary

Problems solved by technology

where warping / fitting (Lloyd DB, Govindaraju N K, Quammen C, et al. Logarithmic perspectiveshadowmaps[J]. ACM Transactions on Graphics, 2008, 27(4): Article No.106) and z-segmentation (Lloyd DB, Tuft D, Yoon S e, et a1. Warping and Partitioning for Low ErrorShadowMaps [C]. Proceedings of the 17th Eurographics Conference on Rendering Techniques. Aire-la-Ville: Eurographics Association Press, 2006: 215-226) method is more efficient, But they can only make the aliasing evenly distributed in the scene, the processing effect of aliasing is still heavily dependent on the size of the resolution, and the warping / fitting method cannot deal with projection aliasing

Adaptive segmentation (Fernando R, Fernandez S, Bala K, et al. Adaptive shadow maps [C]. Proceeding of the 28th annual conference on Computer graphics and interactive techniques (SIGGRAPH'01). New York: ACM Press, 2001: 387-390) Algorithms such as Aila T, LaineS.Alias-free shadow maps[C]. Proceedings of the FifteenthEurographics conference on Rendering Techniques. Aire-la-Ville: Eurographics Association Press, 2004: 161-166) can theoretically completely avoid shadow maps. Aliasing problem, but the efficiency of the algorithm is low, and it does not directly play a big role in real-time applications

On the other hand, compared with the original shadow map algorithm, which only needs to store a single-channel depth map, methods such as z-segmentation, adaptive segmentation, and aliasing removal require more additional shadow map storage space.

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