||Select V-Ray Volume Grid|| > Modify panel > Rendering rollout > Volumetric Options... button > Volumetric Render Settings window
Based on | difSource – Specifies darg – Specifies the source channel used to determine the smoke color. By default, it is a uniform simple color.
Disabled – Disables the diffuse color.
Temperature – Uses the temperature channel.
Smoke – Uses the smoke channel.
Speed – Uses the magnitude of the velocity channel.
Texture – Uses an external texture map.
Constant color – Uses the color in the Constant color swatch.
RGB – Uses a plain color.
Fuel – Uses the fuel channel.
Texture | difTexture dtxt – If the Based on parameter is set to Texture, or if Modulate is enabled, this slot specifies the texture to be used.
Modulate | difModulate mod_d – When Based on is not set to Texture and this option is enabled, the Texture slot is enabled and the color is multiplied by the texture in the Texture slot.
Reset to Defaults – Resets the settings to their default values.
Constant Color | difSimpleColor simple_color – Specifies the color to use if Based on is set to Constant color.
Use Light Cache | difLightCache – lightcache – Enables light caching for each voxel of the grid. This speeds up rendering considerably when the voxel size of the grid is significantly larger than the rendering pixel. If the grid resolution is large enough compared to the rendering resolution, disabling the light cache will speed up rendering.
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Light Cache Speedup | difLightCacheSR subred – This value affects the amount of light sampling. Lower values cause less sampling, which speeds up the rendering but decreases the smoke's quality and increases noise. This option is available only when Use Light Cache is enabled.
Scattering | difScattering – noscatter – Controls how the light rays are scattered inside the volume.
Own Light Scatter Mult | difOwnLightsBoost transfown – Multiplies the distance that light from emissive lights travels through the volumetric. This value doesn't alter the visual density of the smoke to the camera, and only applies to the illumination. This value affects the lighting only when Scattering is set to Analytic or Analytic+shadows.
External Scatter Mult | difExtLightsBoost – transfext – Multiplies the distance that light from all external light sources travels through the volumetric. This value doesn't alter the visual density of the smoke to the camera, and only applies to the illumination. This value affects the lighting only when Scattering is set to Analytic or Analytic+shadows.
Shadow Strength | difShadowStrength shad_strength – Multiplies the opacity of the shadow that the volumetric casts on other objects.
Master Multiplier | difMult difmul – A general multiplier for the diffuse color. This value is ignored when Scattering is set to Ray-Traced (GI only).
Color gradient | dcolorx_t, dcolory_t, dcolorx_s, dcolory_s, dcolorx_v, dcolory_v, dcolorx_f, dcolory_f – If Based on is set to a channel of the VRayVolumeGrid, this parameter controls how the smoke color appears based on the channel's value. The selected channel's data range is denoted by a blue-green line.