Caustics Problem

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HHS
Posts: 7
Joined: Sun Apr 10, 2022 11:50 am

Caustics Problem

Post by HHS »

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?
Attachments
CausticsTest.zip
(508.11 KiB) Downloaded 90 times
epilectrolytics
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Re: Caustics Problem

Post by epilectrolytics »

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.
kintuX
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Re: Caustics Problem

Post by kintuX »

Yup, same here :? or what

CausticsTest.blend.jpg
bdjones
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Joined: Sun Feb 14, 2021 9:30 pm

Re: Caustics Problem

Post by bdjones »

I have to drop the opacity of the glass below 1 for the caustics to show back through the plane.
HHS
Posts: 7
Joined: Sun Apr 10, 2022 11:50 am

Re: Caustics Problem

Post by HHS »

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)
Attachments
SkyAttached.jpg
HHS
Posts: 7
Joined: Sun Apr 10, 2022 11:50 am

Re: Caustics Problem

Post by HHS »

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...
Attachments
HDRi_noCaustics.jpg
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Sharlybg
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Re: Caustics Problem

Post by Sharlybg »

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
(328.37 KiB) Downloaded 103 times
Render:
untitled.jpg
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bdjones
Posts: 7
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Re: Caustics Problem

Post by bdjones »

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.
HHS
Posts: 7
Joined: Sun Apr 10, 2022 11:50 am

Re: Caustics Problem

Post by HHS »

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:
Attachments
Sharlybg_try.jpg
HHS
Posts: 7
Joined: Sun Apr 10, 2022 11:50 am

Re: Caustics Problem

Post by HHS »

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
Attachments
UnderwaterPinating_wo_LT.jpg
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