Water caustics question

[mathos]

First of all thanks for the new caustics solver to Ondra and the team! In most cases (metal, glass etc) it works awesome! Now since we were really keen on trying proper water pool caustics that would work both under water as refractive caustics and on the ceiling as reflective caustics I had to jump into it but there something I can't get my head around. The refractive works well - as seen on the picture, but at the same time it produces these hotspots on the ceiling. As soon as the caustics checkbox is disabled in the material it goes away. What are these dots and is there a way to get rid off them?

Second part of the question - is anyone able - or is it even possible to produce the reflective caustics with the same water material? We are able to get something reasonably nice reflecting on the ceiling if the water gets really reflective (metal level of fresnel) which makes the water surface look unnatural - or with another "fake" water plane with rayswitch material that has basically mirror material plugged into the GI slot.

Thank you in advance!

[mathos]

Ok, got an answer to first part of the problem - the spots - that comes from the environment - once unchecked its fine....

[maru]

Hi,

Ad question 1) How long did you render your image and on what hardware? Did you use region rendering?
Caustics can sometimes take longer to converge to high quality result. They should however definitely become splotch-free after some time.
When using regions, they are calculated in a slightly different way, and this is currently expected, so the "splotches" may actually remain for a longer time then when regions are not used.
Also, did you change any render settings? Have you tried resetting them to factory defaults? (Render Setup > Scene > Reset settings)
And lastly, make sure you are using Corona 4 Hotfix 1, not just the regular Corona 4 release.

Ad question 2) Yes, it should be possible with a "standard" water material with refraction and reflection IOR @ 1,33. It depends on many things, mainly light intensity and direction. What kind of lighting are you using?
You should also model your water as a solid box, with the top face displaced, and contained within some kind of pool, rather than a plane with no thickness floating above the ground. (if that's the case, I am not sure)