Ray Maps for Global Illumination
In Eurographics Symposium On Rendering, Kavita Bala, Philip Dutré (editors, Vlastimil Havran, Robert Herzog, Hans-peter Seidel · 2008
Fast rendering of high quality images with global illumination is still a challenging task. A popular technique addressing this topic is photon mapping [Jensen 2001]. Photon mapping uses a global photon map for indirect illumination and a caustics map for caustics. In order to achieve visually pleasing results a costly final gathering step is commonly used with the global photon map since a simpler direct visualization would produce significant boundary artifacts. The artifacts are caused by using only photon hits on object surfaces: photons passing nearby an object are not accountedfor which underestimates indirect illumination on the object boundaries (see Figure 2, right top). We have developed an efficient technique that eliminates the boundary artifacts and thus it helps to avoid the final gathering. We have extended the concept of photon maps to ray maps. Instead of storing only the photon hits the ray map stores also the photon