Volumetric lighting allows effects such as the scattering of light, by fog or smoke, in a scene. To use this effect, select the Scattering check box on each light. A Scattering Medium foreground effect must also be in use (see Foreground Effects for more information).
Note: You may need to adjust the Medium Density and Medium Ambient parameters of the Scattering Medium foreground effect to suit your model. If no volumetric effects are visible, the Medium Density is too low. If the rendered image is entirely white, the Medium Density is too high.
The default medium is plain white. Optionally, a density shader may be set to any solid (not wrapped) color shader, to create the effect of a non-uniform (inhomogeneous) medium. Examples of shaders that can be used are Blue Marble and Solid Clouds. A shader that has been designed explicitly for this purpose is the Turbulent shader.
The key points when using volumetric lighting are:
- Remember to turn the Scattering parameter of light sources on if you want to see their volumetric effects.
- Use Medium Density and Medium Color to define brightness and color of the lit medium.
- Use a solid color shader set as density shader for simulation of density variations in the medium.
- Decrease the Error Bound parameter, if image appears spotty outside shadow areas.
- Increase the Min LOD parameter, if areas with volumetric shadows appear spotty.
- For fast previews, set the Error Bound parameter high, and the Min LOD parameter small.
- For best results, set the Fall Off option to Inverse Square Law, and turn on Auto Exposure.