This page provides general information about the Mesh sub-section of the Rendering tab of the V-Ray Volumetric Grid.
Displacement is a technique intended to add detail to the simulation during the rendering. The idea of displacement is similar to the usual geometry displacement: a texture is sampled and the point is shifted in a direction at a distance determined by the texture.
Displacement Amount | rendDispl, rendDisplEnbl – Specifies a displacement strength multiplier.
Texture | rendDisplFine – Specifies the displacement map. Depending on the Type option selected, a monochrome map or a color map could be required. If a colored map is specified when a monochrome map is needed, the strength of the displacement is determined by the total intensity of the color. If a monochrome map is specified when a vector map is needed, the entire displacement points in a single direction. See the Advection Displacement with a Monochrome Map example below.
Type | rendDispltSurf – Specifies the displacement technique. In Mesh rendering mode, vector displacement is always used.
Gradient driven – Requires a monochrome texture map. The point is shifted toward the field's gradient by the texture brightness. This method is suitable for smoke and fire.
Surface driven – Requires a monochrome texture map. The point is shifted by the texture brightness toward the normal of the point's projection on the isosurface. The texture is also sampled at the projection point. The Surface driven method is slower than Gradient driven but produces better results that are more similar to displaced geometry.
Vector – Requires a colored vector texture map (with negative and positive values). The point is shifted by the texture color interpreted as a 3D vector. This displacement mode is intended to be used with the Ocean Texture | PhoenixFDOceanTexture texture but can be used with any other vector displacement texture.
Advection – Requires a colored vector texture map (with negative and positive values). A very similar method to Vector, but does not produce grainy structures for fire and smoke. Can be combined with the Grid Texture | PhoenixFDTexture, with the Grid Texture's Channel set to Velocity, to produce render-time advection. For more information, see the Advection Displacement example below.
The difference between Surface driven and Vector displacement is that vector displacement can produce more complicated surfaces. For example, a wave texture in Vector mode produces waves that have a convex back side and a concave front side, in contrast with the symmetrical forms produced by Surface driven displacement.
Example: Advection Displacement
Regular smoke and fire, 5M cells
Advection displacement with the simulation's own velocity,
using a PhoenixFDTexture and multiplied by a noise map.
Example: Advection Displacement with a Monochrome Map
This example illustrates how displacement is affected when a monochrome map is passed when a vector map is needed.
Advection Displacement with a vector map between -1 and 1
Advection Displacement with a monochrome map between 0 and 1
Note that the displacement effect points in a single direction.