Author Topic: New Noise spread in the whole render while Rendering Regions  (Read 3267 times)

2020-10-08, 14:26:47

zules

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Hi there !
I dont understand, when I render Regions after a full render, even if "don't clean VFB between renders" is ticked, noise spread in the whole render while rendering the regions.
Why do this happen ?

Thanks !

2020-10-08, 14:30:50
Reply #1

TomG

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What host software, what version of Corona, all scenes (even a simple test one) or just one? Also to confirm you mean, do a full, non-IR render; enable render regions, and do another non-IR render; the parts of the render outside the region then appear noisy, even once the render is complete and denoising has done its work?
Tom Grimes | chaos-corona.com
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2020-10-08, 16:53:26
Reply #2

maru

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As far as I understand you are rendering new regions on top of an old noise-free image, is that right?
In such case it is expected that the newly-rendered parts will be noisy compared to the previous noise-free render. This is because you are overlaying a noisy image on top of a noise-free image.
Marcin Miodek | chaos-corona.com
Chaos Corona Support Team Lead | contact us

2020-10-29, 16:30:00
Reply #3

zules

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Hi there, sorry I didnt receive any notification of your replies.

TomG : 3ds 2020.3 Crn 6, doing a new scene right now, cant share the whole pic but you can see new noise on noise-free part on the top, free noise part staying free in middle, then region being rendered below.

Maru : yes this it, so its normal ? So I dont understand how it's useful to use region render if the rest gets noisy...

2020-10-29, 16:40:56
Reply #4

TomG

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As a note, Marcin is asking about the parts being re-rendered, that is, the parts in the render region. I believe you are saying something different than what he was asking which is, you render an image and let it finish, you set a render region, you start rendering within that region, and the parts outside of the region become noisy.

My question still stands - do the parts outside the region remain noisy once the render using regions is complete and the denoising has finished?

I'll also ask whether "Clear VFB between renders" is enabled in the System tab of the Render Settings (if it is, then the VFB will indeed "delete" everything outside the regions when you start the new region render). I know you said it is disabled, but are you sure? :)

Everything is working as expected here - I have Clear VFB disabled; I render to completion (final render); I draw a region; I start another final render; the previously rendered parts stay as final, and the region gets noisy and finally clears up.

And, are you using just one render region, or multiple? Do you have some feathering enabled for the region (your image looks strange, as there is the region being re-rendered, a clean part around that, then a noisy part around that even further away). Is anything changed, such as resolution? IR isn't being used at all at any step?

I keep adding questions, sorry :) You are only using Corona VFB regions, you haven't enabled Max Render Regions at all?
« Last Edit: 2020-10-29, 16:44:28 by TomG »
Tom Grimes | chaos-corona.com
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2020-10-30, 15:08:19
Reply #5

zules

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Wow, nice support keep asking ;)

This is it : you render an image and let it finish, you set a render region, you start rendering within that region, and the parts outside of the region become noisy
The render end, then I do some mofification in the scene, draw a region, then render : the region become noisy that's normal, but also so parts of the image.

Yes they stay noisy.

Clean VFB is not ticked, sure.

No : Everything is working as expected here - I have Clear VFB disabled; I render to completion (final render); I draw a region; I start another final render; the previously rendered parts stay as final, and the region gets noisy and finally clears up. : in my case, the previously rendered parts become noisy at some place, not the whole frame.

I use both, but here it was multiple ones.

2020-10-30, 15:44:32
Reply #6

TomG

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Well, we have to keep asking to have a clear picture of what is going on, so we can try to replicate it here (because it's not happening for us, so there must be something different in your set up). Any chance of the scene itself by private uploader, with the regions set up in that you use? That would remove the need to ask questions :)

(also - no Max render regions used just the VFB? IR never used at any point? Any feathering set around the edges of the Render Regions?)
Tom Grimes | chaos-corona.com
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2020-11-03, 17:26:42
Reply #7

maru

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I wasn't able to reproduce this. Used Corona 6 HF1 and Max 2021. Here is my repro:
- Create/open a scene which is noisy when rendering (used a random interior scene)
- Make sure "Clear VFB" is disabled in Render Setup > System
- Render the whole image to reasonable quality (so that the noise is barely visible) - regions disabled, just regular full-frame render
- Stop rendering
- Draw a Corona region in the middle of the VFB (using the region button in the Corona VFB)
- Start rendering again, wait for the image inside the region to refine
- While rendering the region, observe the area around the region - I did not notice any decrease in the quality or change in the noise level - it just stayed the same as in the originally rendered image
- Stop rendering
- Again inspect the region and the area outside of it

I tried this with no denoising and with the Corona High Quality denoiser enabled. It was always the same.

Are you using some kind of denoising here?
Are you able to share your scene so that we could try reproducing this?
Marcin Miodek | chaos-corona.com
Chaos Corona Support Team Lead | contact us