||Select V-Ray Volume Grid|| > Modify panel > Rendering rollout > Volumetric Options... button > Volumetric Render Settings window
Based on | difSource – 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 – If the Based on parameter is set to Texture, or if Modulate is enabled, this slot specifies the texture to be used.
Modulate | difModulate – 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 – Specifies the color to use if Based on is set to Constant color.
Use Light Cache – | difLightCache – 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.
|UI Text Box|
Light Cache Speedup | difLightCacheSR – 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 – Controls how the light rays are scattered inside the volume.
Ray-Traced (GI only) – If Global Illumination is enabled, this mode enables the scattering of light rays. Otherwise it is the same as Disabled.
Disabled – In this mode the scattering of light through the smoke is disabled. The Master Multiplier can be used to correct the brightness of the diffuse color in this mode.
Analytic – Without actually altering the rays, an analytic formula is used to calculate the contribution of the scattering to the illumination. Brighter smoke transfers light further than dark smoke. This effect can be controlled from the Constant color box. This option is not supported when Mode is set to Volumetric Geometry.
Analytic+shadows – Same as Analytic, but geometry is also affected via the shadows. This option is not supported when Mode is set to Volumetric Geometry.
Own Light Scatter Mult – | difOwnLightsBoost – 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 – 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 – Multiplies the opacity of the shadow that the volumetric casts on other objects.
Master Multiplier | difMult – A general multiplier for the diffuse color. This value is ignored when Scattering is set to Ray-Traced (GI only).