Author Topic: 01.2022 compositing issues  (Read 10711 times)

2022-01-29, 23:22:43

user116

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Hi. Can you please fix this ? This just does not look right.
Needles are opacity cards. When you render them agains bright background they just dissolve and thus the trees lack any volume. It does not matter if the background is HDRI or Corona Sky, does not matter how high you set up Hihlight compression, if you set up Highlight clamping or not.

2022-01-30, 03:18:38
Reply #1

lupaz

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Actually I was curious about the same thing. Alpha channels come with a black (or whatever background there is) contour. Can the alpha take alpha as transparent as opposed to the background while rendering?

2022-01-30, 09:21:59
Reply #2

user116

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Yes, the difference is obvious and brutal. Better example where the trees do not overlap - impossible to build any volume with single tree which is somewhat dense in itself. Bright background, dark override, and composited image saved with alpha channel and background added in post.
Pretty please address this guys. Thank you

2022-01-30, 09:27:02
Reply #3

LorenzoS

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2022-01-30, 16:42:23
Reply #4

Yuriy Bochkaryov

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Quote
Hi. Can you please fix this ? This just does not look right.
Needles are opacity cards. When you render them agains bright background they just dissolve and thus the trees lack any volume. It does not matter if the background is HDRI or Corona Sky, does not matter how high you set up Hihlight compression, if you set up Highlight clamping or not.
I also wrote about this problem, but no one answered me
everyone is silent

2022-01-31, 11:43:53
Reply #5

piotrus3333

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just render on black or do not replace background. there is nothing to fix hence the silence.
Marcin Piotrowski
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2022-01-31, 12:19:01
Reply #6

Yuriy Bochkaryov

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just render on black or do not replace background. there is nothing to fix hence the silence.
strange offer
why render on black?
how is this justified?
maybe you need to fix the error and there will be no more problems
2022 - and we need a black background to render coniferous plants
I think it's wrong

2022-01-31, 12:51:40
Reply #7

piotrus3333

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on the edges of those conifiers green pixels with value of 0.25 are mixing with blue sky pixels well above 1.0. you are just loosing them: 0.25 and sky will often blend to 1+. not so green any more.
you want to preserve this green 0.25 for future compositing? every possible pixel of it? render on black 0.0.
Marcin Piotrowski
youtube

2022-01-31, 12:57:29
Reply #8

Yuriy Bochkaryov

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on the edges of those conifiers green pixels with value of 0.25 are mixing with blue sky pixels well above 1.0. you are just loosing them: 0.25 and sky will often blend to 1+. not so green any more.
you want to preserve this green 0.25 for future compositing? every possible pixel of it? render on black 0.0.
does everything work correctly?
there is no problem, nothing needs to be fixed, everything works correctly?

2022-01-31, 13:36:17
Reply #9

lupaz

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on the edges of those conifiers green pixels with value of 0.25 are mixing with blue sky pixels well above 1.0. you are just loosing them: 0.25 and sky will often blend to 1+. not so green any more.
you want to preserve this green 0.25 for future compositing? every possible pixel of it? render on black 0.0.

Rendering on black is fine. The issue is that the alpha channel leaves pixels on the contour. So you need to keep on working on post to remove them.

2022-01-31, 13:48:52
Reply #10

piotrus3333

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on the edges of those conifiers green pixels with value of 0.25 are mixing with blue sky pixels well above 1.0. you are just loosing them: 0.25 and sky will often blend to 1+. not so green any more.
you want to preserve this green 0.25 for future compositing? every possible pixel of it? render on black 0.0.

Rendering on black is fine. The issue is that the alpha channel leaves pixels on the contour. So you need to keep on working on post to remove them.

and it is ok in Corona 7?
Marcin Piotrowski
youtube

2022-01-31, 14:24:26
Reply #11

Dionysios.TS

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just render on black or do not replace background. there is nothing to fix hence the silence.

This is not the solution!

I've tried many times in the past and the black background leaves small black artifacts on the edges of the foliage objects.
As a fast workaround, I render the image with the background I'll use in post so the defect is minimized but in any case is still there.

I agree with Yuriy, there is something wrong and needs to be fixed.

Thanks.

2022-01-31, 14:32:38
Reply #12

LorenzoS

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I've tried many times in the past and the black background leaves small black artifacts on the edges of the foliage objects.
As a fast workaround, I render the image with the background I'll use in post so the defect is minimized but in any case is still there.
same workflow for me

Quote
I agree with Yuriy, there is something wrong and needs to be fixed.
+1

for who work with external views I think it is a big limitation.



2022-01-31, 15:08:17
Reply #13

lupaz

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on the edges of those conifiers green pixels with value of 0.25 are mixing with blue sky pixels well above 1.0. you are just loosing them: 0.25 and sky will often blend to 1+. not so green any more.
you want to preserve this green 0.25 for future compositing? every possible pixel of it? render on black 0.0.

Rendering on black is fine. The issue is that the alpha channel leaves pixels on the contour. So you need to keep on working on post to remove them.

and it is ok in Corona 7?

No.

This should be a separate thread for Corona in general.

2022-01-31, 15:50:39
Reply #14

maru

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Hi. Can you please fix this ? This just does not look right.
Needles are opacity cards. When you render them agains bright background they just dissolve and thus the trees lack any volume. It does not matter if the background is HDRI or Corona Sky, does not matter how high you set up Hihlight compression, if you set up Highlight clamping or not.

^This is the message the whole compositing discussion originated from.

This behavior is expected in any renderer, and it also happens in real life.

If a thin or transparent object is against a bright background, its borders will contract.

Yes, you CAN negate that effect by using highlight clamping (see the attached examples, max scene, comparison):
https://corona-renderer.com/comparer/nrPkPH

If you cannot reproduce this in some other renderer or in photography, please post some examples and explanation how you did it.

Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us