Materials tab - PI-VR GmbH

» Caustic Lookup Radius: The caustic lookup radius specifies the radius around ascenes’s hitpoint used by the raytracer to find caustic photons around the hitpoint.a larger radius allows the raytracer to find more photons but may result in slowerlookup times. For caustics, only the closest photons are actually used.» Indirect Lookup Radius: The indirect lookup radius specifies the radius around ascene’s hitpoint that the raytracer uses to find indirect illumination photonsaround the hitpoint. A larger radius allows the raytracer to find more photons butmay result in slower lookup times. More photons result in smoother results.» Final Gather Quality: There are two ways to use the photon map. The first approachis always used for caustic photons. It gathers photons around a hitpoint tocalculate the incoming illumination. This approach gives very fast interactive performanceand is capable to calculate all light pathes in a scene, but it may requirea very high photon count to get a clean image.the other approach is to use final gathering. In final gathering a one bounce indirectillumination is performed before evaluating the Photon Maps. This is the defaultPhoton Tracing approach in VRED since it generates high quality images ina very short time.Setting the final gather quality to 0 enables the first approachwhile setting it to any other value uses the second approach.» Final Gahter Refresh: Setting the Final Gather Quality to 1 or higher, the updatefrequency of the Photon Map may be set. By default the Photon Maps are updatedfor each image sample, sending a large number of photons into the scene. Whilethis is necessary if final gather quality is set to 0 it is often sufficient to update thephoton Map only once per frame and use it for each image sample to reduce therender times.» On Each Sample: This updates the Photon Map for each image sample. This is thedefault setting since it also works for scenes with animated objects that may causeflickering otherwise.» On Scene Change: The Photon Map is updated once per frame only unless motionblur is activated. Since caustics require many photons, the Caustic Map will stillbe updated for each sample while the indirect illumination Photon Map will only beupdated once. This setting often results in the best rendering performance but289