Region render does not work if Vfb effect is used

[mgibeault]

If I use effects like exposure correction or lens effect, the region render tool does not work, it produces an image with different contrast/exposure...

[Peter.Chaushev]

Hello, Marc,
I was not able to reproduce the issue.
Could you please provide a step-by-step description as well as a screenshot illustrating the problem?

Kind regards,
Peter

[mgibeault]

Hi Peter,

I made a test with 3.6 and I did not see the problem... I'll report if I see this again.

Thanks!

[Peter.Chaushev]

Thank you! Any bug or workflow reports will be appreciated.

Kind regards,
Peter

[palosanto]

Rendering with region render in the Vfb on top of a previous render, (useful to correct small errors or omissions), clears the rest of the area outside the red outline when the render finishes ! However, the previous image seems to be still somewhere in memory because if I render again with region, the full images re-appears in the Vfb when I start the new render but it disappears again when the render finishes leaving everything black except the selected area rendered. Please fix this asap !

[Peter.Chaushev]

I assume you are probably using Denoiser or Lens effects. Both their output is displayed in the VFB's EffectsResult render channel which is created based on the rendered data from the other channels.
This channel is cleared every time the render process is initiated. If you've cropped a region, upon re-rendering only the image within the boundary will be present in EffectsResult while the rest of the channel remains black. This is expected behavior.
If you switch to the RGB channel you will be able to see the previous render output when you start region rendering.

Kind regards,
Peter

[mgibeault]

Peter, this kinda mean that render region is not usable when we use Denoiser or Lens Effects. That's the problem I was seeing and reporting in the first post above.

[Peter.Chaushev]

Correction: In v3.6 this should happen only if there have been no valid auxiliary render elements prior to region rendering. (e.g. previous render was not done with Denoiser on).

[palosanto]

Peter, I just noticed that this has not been fixed ...
I have no denoiser or lens effect active and if I render a region (selected in the viewport not the red rectangle in the VfB), the previous render clears and the VfB window resizes and only the region is rendered. The previous render is gone even though I'm in the RGB channel.

[palosanto]

I assume you are probably using Denoiser or Lens effects. Both their output is displayed in the VFB's EffectsResult render channel which is created based on the rendered data from the other channels.
This channel is cleared every time the render process is initiated. If you've cropped a region, upon re-rendering only the image within the boundary will be present in EffectsResult while the rest of the channel remains black. This is expected behavior.
If you switch to the RGB channel you will be able to see the previous render output when you start region rendering.

Kind regards,
Peter

Going back to this issue with region render. I hear what you are saying and yes, I'm using the denoiser. The problem is that, after re-rendering the croped region, the denoiser is applied to only that small region and I loose the denoise effect in the rest of the image. The only workaround is to save the whole denoised image first, re-render the region, then save again and work out the final image in Photoshop which defeats the purpose of using the render region in the VfB. Is this the only way ? Any way to re-apply the denoiser to the whole image right in the VfB?

Incidentally: Why is the region rendering icon on the VfB labelled "Link VfB to PDPlayer"

[Peter.Chaushev]

Any way to re-apply the denoiser to the whole image right in the VfB?

Let's say you've rendered an image and denoised it. Then, you want to re-render a specific region and denoise it as well. To get the combined result of both denoised renders, you can do the following:
1. Render the whole image once, have the Denoiser enabled (it will create its own auxiliary channels as well)
2. Make changes to the scene and re-render only the region encompassing the changes. The effectsResult channel will appear black outside the region frame
3. Deselect the region (click the VFB region button once), then open the Asset Editor's right Settings Panel, navigate to the Render Elements > Denoiser section and click the Recalculate button at the bottom
4. The updated effectsResult channel will contain both denoised outputs.

Would this workaround be sufficient to your needs?

Incidentally: Why is the region rendering icon on the VfB labelled "Link VfB to PDPlayer"

This is a known issue. The mismatched labels will appear correctly in the next major version. The buttons themselves behave as they should.

Kind regards,
Peter

[palosanto]

Thanks Peter. That worked !