Sintorn, ErikEisemann, ElmarAssarsson, Ulf2015-02-212015-02-2120081467-8659https://doi.org/10.1111/j.1467-8659.2008.01267.xThis paper introduces an accurate real-time soft shadow algorithm that uses sample based visibility. Initially, we present a GPU-based alias-free hard shadow map algorithm that typically requires only a single render pass from the light, in contrast to using depth peeling and one pass per layer. For closed objects, we also suppress the need for a bias. The method is extended to soft shadow sampling for an arbitrarily shaped area-/volumetric light source using 128-1024 light samples per screen pixel. The alias-free shadow map guarantees that the visibility is accurately sampled per screen-space pixel, even for arbitrarily shaped (e.g. non-planar) surfaces or solid objects. Another contribution is a smooth coherent shading model to avoid common light leakage near shadow borders due to normal interpolation.10.1111/j.1467-8659.2008.01267.x1285-1292