ABSTRACT
In this chapter, wewill concentrate on sampling error introduced in the initial sampling phase (i.e., undersampling) and present several methods to improve sampling. One of the simplest methods is to t the frustum of the light source to the view frustum (Section 4.1). is is also a requirement for the more advanced methods, for example, warping the shadow map to achieve a better parametrization (Section 4.2) or partitioning the shadow map globally (Section 4.3) or locally (Section 4.4) in order to spend more shadow-map samples where they are needed. Even higher quality can be achieved by calculating shadows for the exact view-
sample locations visible in the nal image (Section 4.5). Alternatively, the reconstruction algorithm can be improved to provide smoother edges (Section 4.6). Finally, temporal aliasing as well as sampling accuracy can be improved by temporal reprojection of shadow-map samples (Section 4.7).
