LuxCoreRender Forums

Hi all,

Since some while I noticed a strange thing while trying to render caustics in a pool with Luxcorerender 2.5 or 2.6.
The strange thing is:

With older scenes created with older Luxcorerender 2.3 or 2.4 I can get caustics in Luxcorerender 2.5 or 2.6 when using caustics light cache.

Newer scenes created with newer Luxcorerender 2.5 or 2.6 alpha (Daily builds) I can`t get any caustics in Luxcorerender 2.5 or 2.6. when using caustics light cache.
With the luxcorerender test scenes I can get caustics (as an example setting the DanishMood or HallBench scene under water ) when using caustics light cache.

I watched every tutorial about getting caustics - it doesn`t work when I create a new scene. When using Light Tracing the caustics are only below the water surface, not visible from above the surface. I checked the normals.

I have attached a test scene where I would expect pool water caustics, but don`t get it. Like there is a invisible switch for caustics ...

Any clues what is going wrong here?

In your file the world background is set to HDRI with no image attached, the white background is blowing out the caustics from the sun.
Once I switch to Sky background the caustics appear: The lighting system was changed in a previous version, possibly that's why sun + white background works in v2.4 but not v2.6.

Yup, same here or what

I have to drop the opacity of the glass below 1 for the caustics to show back through the plane.

epilectrolytics wrote: Sun Apr 10, 2022 8:29 pm In your file the world background is set to HDRI with no image attached, the white background is blowing out the caustics from the sun.
Once I switch to Sky background the caustics appear:
screenshot.jpg
The lighting system was changed in a previous version, possibly that's why sun + white background works in v2.4 but not v2.6.

And that´s exactly what doesn´t happen here. With no HDRi image attached there is no white sky, switch back to Sky background still no caustics
(When I zipped the file, I noticed the HDRi is still too big, so removed them)

bdjones wrote: Sun Apr 10, 2022 9:31 pm I have to drop the opacity of the glass below 1 for the caustics to show back through the plane.

With Light Tracing it seems indeed the case to do so...
But without Light Tracing (but GI cache on) I still don`t get any caustics as I got used to a while ago...

With a proper lighting it work here: https://polyhaven.com/a/veld_fire
Also optimise settings a bit : You can also turn of dispersion for even faster render.

File Render:

HHS wrote: Mon Apr 11, 2022 3:20 pm

bdjones wrote: Sun Apr 10, 2022 9:31 pm I have to drop the opacity of the glass below 1 for the caustics to show back through the plane.

With Light Tracing it seems indeed the case to do so...
But without Light Tracing (but GI cache on) I still don`t get any caustics as I got used to a while ago...

I'm late to the party didn't see 2.3 and didn't play much with 2.4, I think it needs the Light Tracing on now. Which would speed things up if caustics are not needed.

Sharlybg wrote: Mon Apr 11, 2022 4:41 pm With a proper lighting it work here: https://polyhaven.com/a/veld_fire
Also optimise settings a bit : You can also turn of dispersion for even faster render.

File
CausticsTest.7z

Render:

untitled.jpg

Thanks- that`s what I got with your unchanged file after hitting the render button:

bdjones wrote: Mon Apr 11, 2022 4:59 pm
I'm late to the party didn't see 2.3 and didn't play much with 2.4, I think it needs the Light Tracing on now. Which would speed things up if caustics are not needed.

You usually don`t need Light Tracing for caustics under water- here the underwater Paintings Scene from the example files. I removed volume and dispersions for speeding things up, and I used a hdri here- still I get caustics here and visible from above the water