Author Topic: Caustics rendering dark during network/DR rendering  (Read 587 times)

2021-05-28, 16:20:50

RecentSpacesSam

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Hey all,

I'm having a bit of an issue when trying to render caustics - doing a local low res test render they look great - really bright and looking great, however when I try to render over deadline or through DR at high res, they come out much darker.

I've tried doing a quick render at high res (6k vs 2k) and after 3 passes the caustics once again look great. I increased the photons to 15000 to compensate for the high resolution but this doesn't seem to have helped.

I haven't yet tried sending a local render for a long time but may give this a go over the weekend.

All machines are running the same version of max/windows/corona (Max 2020.3, Corona version 6, hotfix 1)

Cheers

2021-05-28, 17:56:55
Reply #1

maru

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Hi Sam!

I need a bit of clarification here:
1) doing a local low res test render they look great
2) when I try to render over deadline or through DR at high res, they come out much darker
3) I've tried doing a quick render at high res (6k vs 2k) and after 3 passes the caustics once again look great

Do I understand right that the issue with dark caustics only appears when rendering in high res over Deadline or DR?
What exactly do you mean by high res?

Generally, there is a known issue with caustics rendering darker as the resolution goes up. This can be worked around by increasing the "initial lookup radius" in the caustics solver's devel settings.
I would recommend doubling the value first, and checking how it works. If they are not bright enough, you can try doubling it again, and so on.
I am not sure if increasing the photon count is a good idea, but if it doesn't result in super high RAM usage and too slow rendering, you can keep the boosted number.

Also, caustics don't currently work correctly with render regions. If you are rendering a region, it just won't work. The only way to make sure they render fine is running a full production render.

(Internal ID=566135445)

2021-06-01, 11:35:05
Reply #2

RecentSpacesSam

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Hi Maru,

By high res I'm referring to 6000x4000px vs 2000x1333px for low res.

I'll try the initial lookup radius value next.

I haven't tried a full test locally but as I mentioned, after 3 passes at 6k it seemed to look ok.


Thanks

2021-06-10, 10:17:38
Reply #3

RecentSpacesSam

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Hi Maru,

Increasing the Lookup Radius worked perfectly for my water, although I did start to notice a lot more fireflies from reflected caustics in the scene.
As such I've been sending two deadline renders
- one for the main scene with lookup radius on 1
- one for just the objects with dark caustics with the radius on 2 or 4

This works great for now but is there any sort of fix on the way for this in future versions?

Cheers

2021-06-11, 13:47:02
Reply #4

maru

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Hi Sam, would you be able to share the scene with us? Or maybe a simplified version of it? Yes, we are planning multiple caustics fixes for the upcoming versions of Corona, and such scenes with issues would be very valuable to us.