What are the suggested settings to use billboards in my scenes ?

It depends of the renderer. These are some tips:

Scanline

  • For shadow maps, use the XShadow plugin.
  • For raytrace shadows, be sure to assign the light in the "Shadows" rollout.
  • Use "Forest Material" with any material as base.


Mental Ray

  • Always assign the light in the "Shadows" rollout.
  • Don't use XShadow plugin. It's not compatible with MR.
  • Use "Forest Material" with a Standard Material as base, and enable "Forest Shader" checkbox in FM. This combination enables a custom shader optimized for MR and billboards.
  • The "Forest Shader" parameters are found in the "Material" rollout of Forest. Use "Self-Illum factor" and "Irradiance Color" parameters to adjust the illumination of the billboards.


VRay

  • Always assign the light in the "Shadows" rollout.
  • Don't use XShadow plugin. It's not compatible with VRay.
  • You can use "Forest Material" with any material as base, as VRayMtl.
  • Enable the Indirect Illumination (GI) to get the best results.