Caustics - Glitches and Freckles

Corona Corona for 3ds Max Help Required
1

Hi Folks,

I wanted to create some nice caustic details for a close-up image.

We came across some problems. Below you will find a screenshot showing the problem and light setup. We created a copy of the scene with only one simple light. Do you have any idea what might cause the problem (glitches in the caustics, looks like some subdiv problem)?

Thanks in advance for the help.

Tests with sigle Corona Light:

M5wZE3f.jpg
M5wZE3f.jpg1064×547 80.1 KB

jccbfJd.jpg
jccbfJd.jpg1113×1138 115 KB

Test with Corona Sun:

sz6sCBv.jpg
sz6sCBv.jpg466×332 59.7 KB

Corona Light Setup:

27F2BhW.jpg
27F2BhW.jpg375×828 55.4 KB

Material setup:

ziPbK9A.jpg
ziPbK9A.jpg829×725 130 KB

2

Hi,

I have some further questions.. Which version of Corona are you using?

Secondly, Caustics are known to be problematic when using render regions. Does this issue also occur when you are not using regions?

Thanks,

Rowan

3

We are using Corona 4.

Yes, we tested with and without regions and the problem still occurs.

4

Hi,

Thanks for the information.

There were some Caustics improvements between Version 4 and the current daily build. So there is a chance that this was already fixed.

Would you be able to try in the current daily build? (v5 27-08-2019) Or alternatively you can send over your scene and we can look into it, instructions on how to do this are in my signiture.

Instructions on how to get the latest daily build can be found here: Daily Builds

Thanks,

Rowan

5

As Rowan said, please try with the newest daily - https://coronarenderer.freshdesk.com/support/solutions/articles/5000570015
Another option is pumping up photons, but careful with that - https://forum.corona-renderer.com/ Lots and lots of white blotches with new caustics #msg153189
We would be also interested in your scene. Can you share it with us?

6

Maru, Rowan,

Thank you for your answers.

Below you will find an example using new Daily Build. Unfortunately, there wasn’t any improvement.

e7btS7Y.jpg
e7btS7Y.jpg1000×1000 184 KB

We have uploaded the scene via Scene Uploader and scene archive(with textures) via Dropbox Uploader. I hope you will be able to open it.

Meanwhile, we will check if bumping up the photons will help in any way.

Cheers,
M

7

Having similar issues with the C4D version in an interior scene. The splotches never go away and caustics never fully “form”. Even the denoiser can’t get a usuable result :\

8

Hi,

Thanks for sending over your scene.
So far I haven’t been able to reproduce your issue. Can you tell me if there are any further reproduction steps I need to take with your scene?

Thanks,

Rowan