algorithm used for importance sampling in Vray?

V-Ray V-Ray for 3ds Max General
1

Hi,

Can Vlado or anyone mention which specific importance sampling algorithm is used in Vray for the Dome Light if an HDR env. map is plugged in? Is it based on a particular SIGGRAPH paper? Is it bi-directional, i.e. based on the BRDF of material as well as the energy distribution in the map? Is the Rect Light being treated by the same algorithm?

I am doing research using Vray as the choice of renderer and would like to add in a bit detail on the technical side.

Thanks.

2

I did not use any particular SIGGRAPH paper for the current implementation (however the algorithm is quite simple and obvious so it’s quite possible it’s described somewhere; I haven’t looked). V-Ray uses multiple importance sampling to blend the results from importance sampling the BRDF and the light separately, rather than sampling the BRDF/light product directly. The texture-mapped rectangle light is treated in a similar way, yes.

Best regards,
Vlado

3

Thank you so much, Vlado, for the reply and explanation on this.

Cheers,
Jason