Volume Rendering

Volume mip maps The Arnold volume node now accepts OpenVDB files with mip-mapped grids, which gives substantial speedups in volumes with a lot of scattering (for example, clouds).

Faster GPU volume rendering

Volume mip-mapping

The Arnold volume node now accepts OpenVDB files with mip-mapped grids. The different mip-map levels are distinguished by '_level_N' suffixes, where N is the mip-map level. Arnold then automatically chooses the appropriate mip-map level during rendering, which gives substantial speedups in volumes with a lot of scattering (for example, clouds) in exchange for mostly small differences in look. Volumes with more mip-map levels can have larger differences in look. Users can also specify mipmap_bias on a volume node or on its instance (by declaring user data of the same name), which adjusts Arnold's automatic mipmap selection by that amount. (ARNOLD-14453, ARNOLD-15056)