caustics thread no. 12456535

[super gnu]

as usual, caustics are a problem.

i have a scene with condensation on a can. it could really do with some sparkly caustics stuff going on.

its both still and animation.. still is 10k res, and there are over 5 million tiny water droplets. animation has droplets flying round a lot.

droplets look kinda flat.

4 large area lights, gi turned off.

in both cases the photon-mapped caustics dont really stand chance. i had a couple of attempts, but after the usual "its calculating for 10 minutes, filling my ram, and there are no caustics visible" effort, i gave up. no way itll work anyway on a scene like this. ram is almost full with the particle calculations anyway.


i understand that brute force GI does its own caustics, but thats only from indirect lighting? is there a way to use that for direct caustics?


is today the day when Vlado says "actually ive found a nice way to do quick raytraced caustics at full detail with no settings to tweak"???

or maybe not.

[kosso_olli]

Photon mapped caustics will not work, because the droplets are too small. Had that a number of times. Brute Force GI caustics worked quite well in this case.

[super gnu]

Photon mapped caustics will not work, because the droplets are too small. Had that a number of times. Brute Force GI caustics worked quite well in this case.

yeah but in that case i cannot use vralights to light my scene? only vraylightmtl? because unless i understand wrong, the refractive gi caustics will only generate caustics from indirect light sources.

[kosso_olli]

yeah but in that case i cannot use vralights to light my scene? only vraylightmtl? because unless i understand wrong, the refractive gi caustics will only generate caustics from indirect light sources.

Thats wrong. Here is an example of pure brute force caustics, only lit by an HDRI and a tiny disc light with huge intensity: https://forums.chaosgroup.com/forum/...s-on-car-paint

[super gnu]

ahh yes, i guess once a ray has passed into a refractive object, its considered a secondary ray, so direct lights are covered. it seems to work very nicely! i can get away with only primary gi engine to keep things relatively speedy... also have quite good control over strength of effect by adjusting generate gi multiplier of droplets. it never occured to me to turn off "affect shadows" when i didnt have photon mapped caustics enabled. i do seem to get some over dark shadows around the edges of the drops, but that can probably be fixed..

thanks

i have no idea, in this case, why the (awful) photon mapped caustics is even still present in vray?

[kosso_olli]

it seems to work very nicely! i can get away with only primary gi engine to keep things relatively speedy.

Don't do this. The light cache is used in numerous situations in order to speed the render up, at least since Next. Having only primary GI is not good...

[super gnu]

Don't do this. The light cache is used in numerous situations in order to speed the render up, at least since Next. Having only primary GI is not good...

well from my testing , on this particular scene, no GI is fastest, then primary only, then BF/BF, and finally BF/LC.. no idea why.

[Ihno]

Turning off or raise Max ray intens. might have a big influence on this. Depending on the energy of your light sources of course.