Refinement criteria for global illumination using convex funcions

In several computer graphics areas, a refinement criterion is often needed to decide whether to goon or to stop sampling a signal. When the sampled values are homogeneous enough, we assume thatthey represent the signal fairly well and we do not need further refinement, otherwise more samples arerequired, possibly with adaptive subdivision of the domain. For this purpose, a criterion which is verysensitive to variability is necessary. In this paper, we present a family of discrimination measures, thef-divergences, meeting this requirement. These convex functions have been well studied and successfullyapplied to image processing and several areas of engineering. Two applications to global illuminationare shown: oracles for hierarchical radiosity and criteria for adaptive refinement in ray-tracing. Weobtain significantly better results than with classic criteria, showing that f-divergences are worth furtherinvestigation in computer graphics. Also a discrimination measure based on entropy of the samples forrefinement in ray-tracing is introduced. The recursive decomposition of entropy provides us with a naturalmethod to deal with the adaptive subdivision of the sampling region

El démon: la inteligencia en el mundo

From Hesiod on, Gctiywv denotes a passionate figure, useful to ffee divinity from the charge of evil. Plutarch conceives Gaiywv as an active and changeable entity between God and rnatter; he must complete a catharsis that makes him better (more akin to God; Being in a higher degree). The task of Gaiyov is to take care of oracles and to guide human lives. If this task has been done correctly, Gaipov ascends to the sun; if not, he falls down to the earth.