Region render passes darker than original

[Pixelcon]

This is an utter pain. It means I cannot region render... Waiting 6 hours for a region, then finding that I will have to do the entire frame again because of this problem is not a minor issue.

It has been persistent for some time now, but it's time to bring it up (again if it has been before).

A region render produces darker passes. Render loaded from history. The denoiser opacity slider is < 1. Running the denoiser from the elements rollout will not fix it. Max 2019. vray_adv_50006_max2019_x64_30545
Attached are some samples.


VrayLighting:


VrayReflection seems to be unaffected.



RawTotalLighting:


GI:

[fixeighted]

This can happen when you have auto-exposure on, which calculates for the region and not the full frame. Just a thought.

[Pixelcon]

No I don't have auto-exposure on. Thanks anyhow!

[Joelaff]

I think any time you use LightCache this can happen because the light cache is being calculated based only on the rendered region.

If you cache your light cache to disk with the full frame initially then you could re-use that cache with identical results... I think...

Or I may be totally wrong.

[Pixelcon]

I think this is an issue that needs to be looked at by Chaosgroup. I appreciate the input guys, but I'm looking for a fix, not a workaround.

[Joelaff]

I'd have to see the scene, but if it is the light cache issue this is by design, and the only FIX is to cache the LightCache or use Brute force

But maybe it is some other GI related issue..

[Pixelcon]

That is not a fix, that is a workaround.

[Joelaff]

You have any bitmap nodes for your textures? If so, try replacing them with VRayBitmaps. We have seen random gamma shifts from Bitmaps. Otherwise, I don't know.

I hope you find the fix you seek. Sadly, the business is all about workarounds.

[Pixelcon]

I should clarify:

It's everything outside the render region that is darkened. The rendered region itself is fine.
If I have a region active, and render mask set to selected, the darkening happens outside the render region, as opposed to everything not selected.

There goes another 4 hours today because I cannot simply region render an update, I have to update the entire image...

Can someone from Chaosgroup please respond?

[fixeighted]

Aaah...I had a feeling it was render mask related when I saw the aliasing....so that is it. Render mask makes this absolutely happen and is a pain.
I posted about this a couple of years ago afair and believe I was told that it is simply is what it is and can't be fixed

[Joelaff]

Are you saving these images out and comping the region over the original image in something like Photoshop or Fusion, etc.? Could you just mask the new image and comp it over only in the region that matters?

Are you using any VFB post layers (lens effects, tone mapping, etc.) at all, or just the render itself? I tried a simples test and could not get the issue you are having to crop up.

Good luck. I hope you get it figured out.

[Pixelcon]

No it's not specifically related to render mask, and in my opinion it shows that it isn't related to render mask (darkening happening only outside region, not outside render mask).
This happens regardless of render mask being enabled or not.

Edit: Also happening when denoiser opacity slider is at 1.


fixeighted: I don't believe this behavior was in vray 3.x so I don't accept this this is now normal behavior

[Pixelcon]

Are you saving these images out and comping the region over the original image in something like Photoshop or Fusion, etc.? Could you just mask the new image and comp it over only in the region that matters?

Are you using any VFB post layers (lens effects, tone mapping, etc.) at all, or just the render itself? I tried a simples test and could not get the issue you are having to crop up.

Good luck. I hope you get it figured out.

I believe you have to load an image from the vfb history and region over the top of that.

I am but every time I do a region on an image, I need another whole set of passes stacked on top? Then I need to combine multimatte selections? No thanks...

[fixeighted]

This is the post from 2019...a fix was apparently on the way...

https://forums.chaosgroup.com/forum/...ent-brightness

[Pixelcon]

This is the post from 2019...a fix was apparently on the way...

https://forums.chaosgroup.com/forum/...ent-brightness

Thank you!