Hello Mr. Legrenzi,

as you show in your caustics tutorial you create the caustics with a spot light with a huge multiplier at 50000 and an inverse square decay with 1cm very near to light start. The result is that the caustics are very nice and bright.

1. When I turn the light multiplier of the spot light to 1 and don't use decay settings the result is that the caustics are not detailled and look bad. Why is this so? I thought that only the caustic subdivisions settings should be important for the caustic detail.

2. When I take a direct light with light multiplier set to 1 the caustics are fine. Why is here a difference to spot light where you get no good results of caustics with light multiplier 1?

Can you or anybody please explain and give some background knowledge.
Thanks.

Daniel Krüger

Hi archvispro,

I think that we must use the decay due to the physical aspect about VRay.
About the difference to Spot and Direct, this is a "in depth" question, so I think you must ask directly to Chaosgroup.
Anyway, the spot light can "shoot" the photon only in the light cone. The Vray Light everywhere. This is why ofter it's better use a spot/direct light.


bye

cecofuli