This page provides information about the V-Ray's new implementation of the volumetric rendering.
Overview
The new implementation of volumetric rendering in V-Ray introduces a completely new system. It enables artists using V-Ray for Houdini to build shading graphs for volumetric rendering and replaces the previous 'blackbox' solution based on the V-Ray VolumeGrid Shader.
The system introduces three new nodes:
- V-Ray Volume Shader – The core node for volumetric shading graphs. Supports VDB volumes only.
- V-Ray Volume Float Sampler – Samples float fields from the VDB file.
- V-Ray Volume Color Sampler – Samples vector fields from the VDB file.
The new system resolves limitations of the previous implementation and offers significant improvements in both functionality and performance.
Improvements
The new implementation of volumetric rendering provides the following improvements over the old 'blackbox' solution:
Motion Blur Improvements
- Resolves inconsistent behavior when non-default Motion Blur Duration and Motion Blur Offset are used.
- Supports downsampled velocity fields for smoother motion blur and reduced VDB cache sizes. In some cases, artists downsample the velocity to reduce the VDB cache size on disk as well as to produce smoother motion blur results.
Light Path Expression Improvements
- Illumination for volumes supports light path expressions. This allows the artist to sample information such as the voxel position, or the ray bounce level through the V-Ray Sampler node to build advanced effects.
Performance Gains
- Produces significantly faster rendering results.
Realistic Volume Rendering
- Features like Density Falloff and Anisotropy Falloff allow for realistic cloud rendering by reducing smoke opacity (denisty) and phase function anisotropy on each ray bounces.