Underwater caustics

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LuxNoob
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Underwater caustics

Post by LuxNoob » Sun Aug 02, 2020 6:52 pm

Hi, after all thanks to devs for this amazing render engine!

So my question is how to make a very basic scene with underwater volumetric caustics like in example scene "Underwater Paintings".

I've already downloaded the example scene, but I dont understand how a mesh without thickness can have a volume, and I cant also replicate the results in my scenes. When I try to replicate the volumetric caustics, they are not so obvious and barely visible. However, caustics in sand are very visible.

Thanks in advance and sorry for bad english.

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B.Y.O.B.
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Re: Underwater caustics

Post by B.Y.O.B. » Sun Aug 02, 2020 7:08 pm

LuxNoob wrote:
Sun Aug 02, 2020 6:52 pm
but I dont understand how a mesh without thickness can have a volume
In that scene, the materials and camera have correctly set interior/exterior volumes.
It should be enough to set the exterior volume of the camera and the interior volume of the water surface though, usually you con't need to specify the exterior volume on every material.

LuxNoob
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Re: Underwater caustics

Post by LuxNoob » Sun Aug 02, 2020 8:13 pm

Thanks for your reply.

However i dont understand: why set up a volume in the camera?

And still, how can i make the volumetric caustics more evident? With possible "tricks" I mean, because mine are barely visible.

Thanks a lot for your support.

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B.Y.O.B.
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Re: Underwater caustics

Post by B.Y.O.B. » Sun Aug 02, 2020 8:28 pm

LuxNoob wrote:
Sun Aug 02, 2020 8:13 pm
However i dont understand: why set up a volume in the camera?
To tell LuxCore which volume the camera rays start in. It is the volume surrounding the camera.
LuxNoob wrote:
Sun Aug 02, 2020 8:13 pm
And still, how can i make the volumetric caustics more evident? With possible "tricks" I mean, because mine are barely visible.
You could try to use a higher scattering scale in the volume.

LuxNoob
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Re: Underwater caustics

Post by LuxNoob » Mon Aug 03, 2020 1:25 pm

Thanks everyone,

I tried your tips, but volumetric caustics are still barely visible. And if I increase the scattering, the scene becomes too bright.
I uploaded the scene if it helps.

Thanks a lot for your patience.
Attachments
vol_caustics.blend
(732.29 KiB) Downloaded 18 times

kintuX
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Re: Underwater caustics

Post by kintuX » Mon Aug 03, 2020 2:01 pm

Basically, you get finer Scattering Scale control with Scattering (color) = Value 0.01
Scale is then set to 50 & with a few other changes to amplify, exaggerate the volume caustics alike...
vol_causticX.jpg
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vol_causticsX.blend
(666.73 KiB) Downloaded 18 times

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B.Y.O.B.
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Re: Underwater caustics

Post by B.Y.O.B. » Mon Aug 03, 2020 2:01 pm

You simply have so many intermingled volumetric caustics in front of each other that they mix together into a uniform mess.

Here is a rendering of your scene with a cover over the water, blocking all the sunlight save from a quadratic spot.
As you can see, you need to take away some caustics in front and behind the ones you want to show in order not to drown them out.
Or modify the water surface so they are focused stronger.
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untitled.jpg
vol_caustics2.blend
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LuxNoob
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Re: Underwater caustics

Post by LuxNoob » Mon Aug 03, 2020 3:51 pm

Thanks a lot kintuX and B.Y.O.B., both of your solutions works pretty well.
This render engine deserves even more users!

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