VRayFur GI behaviour

[insanetk]

What is it that irradiance map do when it renders VRayFur? It's so incredibly fast at it, as if it sees the polygons as just clusters and just gives an average colour. How can I turn this function on for other very detailed polygon objects, like polygonal hair?

[vlado]

For VRayFur, V-Ray only places irradiance map samples along the middle of a fur strand and computes full-sphere irradiance, rather than using just hemispheric sampling. This reduces a lot the number of irradiance map samples, and it is possible because each hair segment is a single primitive and there is no possible self-shadowing.

With geometry, V-Ray does not know that it renders hair, so it must place a lot of samples across the width of individual hairs to capture irradiance properly.

Best regards,
Vlado