6 modules - PI-VR GmbH

6.4 Renderingsamples set to 256 will result in 25.600.000 photons send into the scenefor a frame. More photons result in smoother results.• Use Automatic Photon Radius: A preprocess is doing a lookup of the 16closest photons for each photon in the scene and calculates two times theaverage lookup radius. This feature works for most situations.• Photon Radius: The Photon Radius specifies the radius around a scenes’shitpoint used by the raytracer to find photons around the hitpoint. A largerradius allows the raytracer to find more photons but may result in slowerlookup times.• Final Gather Quality: There are two ways to use the photon map. The firstapproach is always used for caustic photons. It gathers photons around ahitpoint to calculate the incoming illumination. This approach gives veryfast interactive performance and is capable to calculate all light pathes ina scene, but it may require a very high photon count to get a clean image.The other approach is to use final gathering. In final gathering aone bounce indirect illumination is performed before evaluating the PhotonMaps. This is the default Photon Tracing approach in VRED since itgenerates high quality images in a very short time.Setting the final gatherquality to 0 enables the first approach while setting it to any other valueuses the second approach.• Final Gather Radius: Sets the lookup radius used to find the nearest finalgather point during raytracing. Using a smaller radius will increaseperformance but it requires more photons to avoid dark regions. Tip: Toevaluate the final gather points use the “Indirect Illumination Rendering”with photon mapping and final gathering turned on. For a good qualityresult the final gather points should have very few black regions whereno photons are stored.• Final Gather Refresh: Setting the Final Gather Quality to 1 or higher, theupdate frequency of the Photon Map may be set. By default the PhotonMaps are updated for each image sample, sending a large number of photonsinto the scene. While this is necessary if final gather quality is set to201