Caustics - can of worms?

[tricky]

Never really had much practice/success with caustics. We're doing an image of a swimming pool so I thought I'd have a go with them again and make the vray sphere lights below the water around the edge of the pool create a casutic effect through the water so that I could get some nice patterns across the ceilings and walls.

So far, I've managed to achieve a whole bunch of dots across the walls and ceilings, but not a whole lot else.

I'm likely to just fake them (as I always do!) in the end, but wondered if anyone had any pointers on what I should be doing.

The surface of the water is just a mixture of varying sized noise maps in the bump channel.

[vlado]

Can you post an image and your caustics settings?

Best regards,
Vlado

[Drawehn]

I am struggling with caustics as well. I have a glass lamp with bubbles which is lit from inside with a sphere shaped vray light and the only things that's changing when i activate caustics, is the render times (through the roof). Will try and post image and settings one of these days.

I have the real version of the lamp so I know the caustics really should be amazing.

[tricky]

Can you post an image and your caustics settings?

Best regards,
Vlado

Once I've spent a bit of time messing, I will post my setup.

[Drawehn]

Here is my render plus settings. Any hints on how to get the caustics to appear greatly appreciated.

[Dave_Wortley]

Put your Caustic Multiplier on your light up to something silly like 50,000 and then 200,000 to see some caustics working, then tweak settings from there.

[simmsimaging]

I have this quote from Vlado I refer to when doing caustics:

The answer to that would depend on how you are lighting the scene. But in general, I myself would use just the normal caustics (not the directly visible ones), max. photons set to 0, and max. density locked to 1/3rd to 1/4th of the search distance. Then I would play with the Search distance to reach the amount of blurriness that can be tolerated, and then its just a matter of shooting more photons until they become relatively noise-free. Also, I would try to use relatively small light sources or point light sources (large area lights might take a very long time to clear up the caustics in this way).


I still find it very problematic to set up, but these guides help. In your case you may need to increase the intensity, but I think the crazy high numbers are usually only needed with non-vray lights. If your scenes is at fairly normal scale your search distance may be way high though. I tend to do bottles, and at size (say 20cm high) I use search distances that are <1cm quite often, so may try a really low one and see what you get.

b

[vlado]

Do you have the "Affect Shadows" option for the glass material on or off? It needs to be turned OFF for any caustics to appear from that material.

Best regards,
Vlado