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.
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?
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
maybe the “issue” is related to this?
https://forum.corona-renderer.com/ Alpha channel retain refraction information
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
just render on black or do not replace background. there is nothing to fix hence the silence.
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
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.
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?
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?
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.
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
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.
No.
This should be a separate thread for Corona in general.
^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):
If you cannot reproduce this in some other renderer or in photography, please post some examples and explanation how you did it.
opacity-light.max (1.11 MB)
Another issue from the above posts:
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you render something in Corona against some background
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you want to replace the background or move the object into some other place of the image
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you render a mask of this object, save in 32-bit exr with alpha channel, no post processing, and do other fancy stuff to make sure all is fine
-
in the end… OMG BORDERS!
Why?
Because Photoshop is unable to interpret the alpha channel correctly!
Use Fusion (it’s free) or other software that is made specifically for compositing. It will handle just fine whatever complex alpha-channel-masked-32-bit-exr you throw at it.
If you are having issues with this - again, please send us sample files (max, exr, other) and let us know how to reproduce your issue. We will look into it.
I’ll try with fusion later. But yes. With photoshop this is the result:
See below please.
I have two tall boxes. One with physical material and the other with legacy, to discard reflections.
Rendered against an empty background.
I save the image as PNG with alpha included.
In photoshop I add a white background and I can see a darker grey contour.
Edit: I added the Max file
temp.max (832 KB)
Maru thanks for moving the post here and excuse us for the “contamination” of the Daily 8 one.
Anyway, I remember in the old mental-ray days, to proceed with the compositing video process in Combustion I was saving in TGA format with the Pre-Multiplied Alpha option enable and this defect was gone. Now I don’t know how to replicate the same fix in Photoshop as Combustion had a special future for the Alpha channels when they were Pre-Multiplied or not.
Yea, sorry for posting in daily thread.
Concerning the topic - sorry but watching some pictures I still think something is off.
Image credits - Wikipedia
The trees sustain their volume. One can also pretty much see the individual needles.
Is there really no way to mitigate this effect without having to resolve to compositing and work freely in WYSIWG using the (awesome) interactive renderer? Highlight clamping is also no solution as the image gets extremally flat.
