What a stunning image. Couldn’t believe it was all 3D until I found it on Evermotion.
I wish vray had a better caustic method 
I’ve recently completed a project with underwater caustics. It was tough to set it up for every shot. Since the water was covering a large area, moving the directional light around for a big coverage proved difficult and also I had objects traveling for large areas so having crisp caustics was tough, I had to have the photon count super high, like 50,000 
It all comes down to - use pin light source like spot light or dir light as oppose to area light - it will produce soft caustics.
Use low threshold the lower the search distance the more precise the caustic will look, but you will need to increase your photon count a lot for it to look good. If you see in picture below this is with very low caustic search distance, and photon count of 5000 still noisy, so I would raise that to 10000 and it will probably be fine.
2014 max scene attached.
caustics.zip (252 KB)
I’m sure that will be really useful (and to others too), many thanks Dmitry. Forgive me if I don’t give more feedback, don’t have time to play around with it right now!
Np. My issue is with a scene like I attached there, it does not scale well to other scenes/projects. If I was to move this light around, scale the plane etc, the caustics will totally change/disappear (what was happening to me in that project).
That’s a reliable approach if you don’t need to see the caustics through mirror/glass materials. However you don’t need to render several frames. Instead, set the max. density for the caustics to some reasonably small number (2-3 cm perhaps). Then the render will take some RAM, but because nearby photons will be merged instead of simply added to the photon map, it will typically not run out of RAM.
Best regards,
Vlado
Indeed very good tutorial for reflective caustics, but how does one tackle refractive caustics then?
you dont! it’s just to get large scale light patterns to overlay in post later. works real good on external building glass and unique light fixtures - big ones that even a client would notice were missing.
Thanks for that tip vlado!
so refractive caustics arent shown when ‘directly visible’ is ticked?
They will be shown, but only if they are directly visible. Caustics seen through the refractive surface itself will not be.
For the spring service pack we are working in a solution for caustics that works well with the progressive sampler and can handle these cases much much better.
Best regards,
Vlado
Its a bout time to have a better caustic sollution. I’m so tired of having to change render engine to render efficiently my 9-10k caustic passes
Yes, now that we have the progressive sampler, it is a lot easier to implement multipass caustics compared to the bucket sampler.
Best regards,
Vlado
finally. my dreams come true. I can render caustics.
Tommi from work is Tamas Medve from MIR?
Having to do caustics again and just wondered if there was any news on this Vlado? anything in the nightlies to test yet?
I’m curious as to if this solution would include some kind of photon overide for the light so instead of the photons for caustics being cast the same as the photons for diffuse etc you could control a cone that fires them much more tightly/specifically at an area ?
just bumping this thread..
and also wondering if there is any way to render the caustics pass without rendering the main rgb pass?
If you only want the directly visible caustics, turn on the “direct visualization” option and then turn on “don’t render final image”.
Best regards,
Vlado
unfortunately its caustics through water so no directly visible, unless there are some tricks like not renderable geometry or something?
I’ve done that a few times. Turn off the water, render the caustics on black, camera project it back onto the object in an additive mode and render the full image with the water on.