Coarse irradiance estimation using curvilinear skeleton

Light flux can take complex paths to reach the observer, especially in large and sophisticated scenes. In such situations, global illumination algorithms are used: irradiance caching, path tracing and radiosity allow to precisely compute the irradiance at any point of the scene, but remain quite slow. Our present work aims to evaluate, very coarsely, the irradiance of any point of a scene, allowing to give global illumination algorithms some information about the main direction and intensity of the light flux. We use a coarse representation of the scene using a skeleton of its voids (where the light propagates). We present two heuristics to compute a coarse radiance estimation and the main light stream orientation. Our work gives the possibility to define many other heuristics.