Generalized linear perspective shadow map reparameterization

Shadow mapping is an efficient approach for real-time shadow rendering, but it usually suffers from inherent aliasing artifacts due to the image-based nature. The aliasing errors of shadow mapping can be classified into two categories: perspective aliasing errors and projection aliasing errors. In this paper, we present the Generalized Linear Perspective Reparameterization (GLPR) of shadow maps to reduce perspective aliasing errors. The generalized perspective reparameterization function is formulized first, in which three parameters are taken into account: 1) the cross angle between the view and light direction, 2) the distance from the projection reference point to the near plane in the perspective warping frustum, and 3) the pixel's depth. The distribution of perspective aliasing errors of all currently existing perspective reparamterizations can be uniformly described by this function. Based on this generalized representation, the direction-dependent warping transform is chosen to keep the linear perspective aliasing distribution when the light direction is not perpendicular with the view direction.

[1]  Lance Williams,et al.  Casting curved shadows on curved surfaces , 1978, SIGGRAPH.

[2]  Franklin C. Crow,et al.  Shadow algorithms for computer graphics , 1977, SIGGRAPH.

[3]  Pierre Poulin,et al.  A survey of shadow algorithms , 1990, IEEE Computer Graphics and Applications.

[4]  Kok-Lim Low,et al.  Computing a View Frustum to Maximize an Object's Image Area , 2003, J. Graphics, GPU, & Game Tools.

[5]  George Drettakis,et al.  Perspective shadow maps , 2002, ACM Trans. Graph..

[6]  Donald P. Greenberg,et al.  Adaptive shadow maps , 2001, SIGGRAPH.

[7]  Jukka Arvo,et al.  Tiled shadow maps , 2004, Proceedings Computer Graphics International, 2004..

[8]  Pat Hanrahan,et al.  Shadow silhouette maps , 2003, ACM Trans. Graph..

[9]  Michael Wimmer,et al.  Light Space Perspective Shadow Maps , 2004, Rendering Techniques.

[10]  David Salesin,et al.  Rendering antialiased shadows with depth maps , 1987, SIGGRAPH.

[11]  Dinesh Manocha,et al.  Interactive shadow generation in complex environments , 2003, ACM Trans. Graph..

[12]  Tiow Seng Tan,et al.  Anti-aliasing and Continuity with Trapezoidal Shadow Maps , 2004, Rendering Techniques.

[13]  Simon Kozlov.  Perspective Shadow Maps: Care and Feeding , 2004 .

[14]  Jeremy D. Wendt,et al.  A lixel for every pixel , 2004 .