Probabilistic Volumetrics – If – hen Probabilistic Volumetrics is enabled, the volumetrics will select a only few samples along each ray (based on the smoke density) along each camera ray, and evaluate the volume lighting at those points. If When disabled, the volumetrics will evaluate the lighting at each step of the raymarching algorithm. The probabilistic mode regular intervals using many steps along each camera ray, and thus each pixel will take longer to render, but when it's finished, it will have no noise at all. Enabling Probabilistic Volumetrics is particularly useful when using the progressive sampler Progressive Image Sampler in V-Ray, as well as when using complex lighting on the volume. The Probabilistic Volumetrics option makes the shading much faster, but also it can result in noisier renders with low sample counts. This mode only applies to the Volumetric Grid (VRayVolumeGrid) currentlycurrently. When using V-Ray GPU renderer, this option is not available in the UI, but is turned on and the Num. Samples and Num. GI Samples are set to 1.
Num. Samples – The – Specifies the number of probabilistic samples to use when when Probabilistic Volumetrics is is enabled. For the best rendering performance, use a higher number of samples for transparent smoke, and lower number for dense smoke. With A very high number of samples , the sampling basically converges to a will converge to standard ray-marching.
Num. GI Samples – The – Specifies the number of probabilistic samples to use for GI rays . The number of samples depends on whether the volumetric has emissive component. Brighter emission requires more samples, while pure smoke can work with fewerwhen Probabilistic Volumetrics is enabled. This should be kept as a relatively small number in order to speed up GI calculations.
