Page 1 of 1

Caustics on pool

Posted: Fri Dec 13, 2019 10:19 am
by rivera-b
Man, I keep failing to get any caustics on my pool water. Any obvious reasons anyone can think of? I am following the SKindigo water tutorial to the letter. So far, nothing gives me the caustics. Also, takes forever to develop.

Re: Caustics on pool

Posted: Mon Dec 16, 2019 8:04 am
by Polinalkrimizei
Hi rivera-b,

please share more infos about your scene, and if possible an example. Are you rendering with MLT?
And yes, caustics are a bitch considering render times...

Re: Caustics on pool

Posted: Tue Dec 17, 2019 3:23 am
by rivera-b
I've rendered this pool from different angles and under different light conditions. Here I have two Light sources inside it, I like the texture and light filling the pool, but on the night or day scenes, I still get no caustics, even after an all night render time.
I suspect it is a mistake on my part, but I can't put my finger on it.

Re: Caustics on pool

Posted: Tue Dec 17, 2019 3:30 am
by rivera-b
Anyway, I like this water and I think it is fine.

And perhaps I just don't understand the nature of caustics.

Re: Caustics on pool

Posted: Tue Dec 17, 2019 9:15 am
by Polinalkrimizei
Hi rivera-b,

I am no caustics expert either. BUT I would expect that in real life, there would probably be no caustics in your night scene, as caustics happen when a strong light source (=sun) hits the pool from above, causing caustics on the pool walls and floor by interacting with the ripples of the water volume.

So I would think that in your daylight scene, caustics should appear if
- the light source is strong enough and hits the water directly (perhaps you can play with the angle of the sunlight?)
- the pool has real ripples for the sun to deal with

How do you "ripple" your water? When using a displacement map, make sure the subdivison of the water is really high, and perhaps try another map. When using a shader, just play with the values to get more ripples/make the ripples a little deeper.
Rendering with MLT enabled (=using CPU only) should make the caustics appear early on.
Have you tried following the tutorial step by step, without the nice villa in the background?

Best of luck :-)

Re: Caustics on pool

Posted: Tue Dec 17, 2019 9:21 am
by Polinalkrimizei
... just found an old render from 2012 which followed pretty much the tutorial, it seems to work ;-)

Re: Caustics on pool

Posted: Tue Dec 17, 2019 9:24 am
by rivera-b
Thank you! Will tweak the subdivision and the sun angle and see what happens.
Cool image by the way! lol