View Full Version : Caustics in a indoor room render possible?

01-09-2018, 12:36 AM

tried a test scene which comes out ok if caustics is off.
As soon as I enable it, there seems to be no way to get a noise free result.
The image attached is from caustics off. If it is on I can through as many samples as I want, it never cleans.
I tried Env. light, Portal light, high min / max. AA, high individual samples for the various buffers, brute force, interpolated, etc etc.

Did anybody had more luck with such an indoor scene?

(image is a little blurry because Filter Radius was to 1 instead of 0.1)

01-09-2018, 12:53 AM
Hi, can you post the scene? Is it from content?

01-09-2018, 06:09 AM
Not from content.
Will post it when back home in the evening.

01-09-2018, 03:08 PM
Tried to upload the scene and objects. It fails with no hint what's wrong. Maybe files size? The zip is 8.6 MB.

01-09-2018, 05:04 PM
Try to upload on to dropbox or similar service and share the link.

01-10-2018, 12:00 AM
Dropbox Link


I used a highres HDR for Textured Environment. That file is to big to upload and the usage rights do not allow it anyway. So expect to get a warning about missing image.

01-10-2018, 02:52 PM
Have tested it and it is difficult to get rid of fireflies, also the effect is increased due the reconstruction filters.
Clamping does not help. It should be separated clamping for indirect and direct rays.

I have to make more testing.


01-11-2018, 04:04 AM
Well, it seems caustics go to diffuse indirect pass, so you should increase gi samples a lot.

01-11-2018, 09:19 AM
So, render times in case of caustics are still high. Seems so this is a rule of thumb: "if you want caustics then invest time".

01-11-2018, 10:07 AM
I think lw is not made for caustics, nor other unidirectional path tracers.

01-11-2018, 01:59 PM
It's not very easy to get right anyway. And I don't know if it correctly splits the white into a spectrum of colors either.

01-12-2018, 12:00 AM
Don't seems to be spectral. Only a few renderers are.
But I might be wrong.

01-12-2018, 01:18 AM
I haven't had any success with that so far at least.