6 modules - PI-VR GmbH

6 MODULES148· Indirect Only: Uses photon tracing to calculate the indirect illuminationin a scene. This is the most common mode.· Caustics + Indirect: Uses Photon Tracing to calculate indirect illuminationand caustics due to specular materials in a scene.• Interactive and still frame count: The two photon count values specify thenumber of photons being sent into the scene for each image sample. Specifyinga photon count of 100000 photons while having set the image samplesset to 256 will result in 25.600.000 photons send into the scene for a frame.More photons result in smoother results.• 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. Thefirst approach is always used for caustic photons. It gathers photons arounda hitpoint to calculate the incoming illumination. This approach gives veryfast interactive performance and is capable to calculate all light pathes in ascene, 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 a one bounceindirect illumination is performed before evaluating the Photon Maps. This isthe default Photon Tracing approach in VRED since it generates high qualityimages in a very short time.Setting the final gather quality to 0 enables thefirst approach while setting it to any other value uses the second approach.• Final Gather Radius: Sets the lookup radius used to find the nearest finalgather point during raytracing. Using a smaller radius will increase performancebut it requires more photons to avoid dark regions. Tip: To evaluatethe final gather points use the “Indirect Illumination Rendering” with photon mappingand final gathering turned on. For a good quality result the final gather pointsshould have very few black regions where no 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 Photon