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Chaos Corona Forum
Chaos Corona for Cinema 4D
[C4D] General Discussion
opacity mask problem
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Topic: opacity mask problem (Read 4748 times)
2021-04-30, 16:10:40
mitchino
Active Users
Posts: 86
opacity mask problem
I'm rendering a yoghurt pot. I want to create an opacity map so the top of the yoghurt fades away to transparency over a short distance. I have created this as a black and white map in Photoshop, blurred it, and applied it to the opacity channel. I'm getting an ugly darkening at the transparent edge of the mask. This doesn't happen if the map is not blurred.
This pic demonstrates the problem, to exaggerate it I've created a map with castellations.
How can I fix this and have the edge fading to transparency cleanly?
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2021-05-01, 11:56:33
Reply #1
mitchino
Active Users
Posts: 86
Re: opacity mask problem
Anyone care to comment?
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2021-05-01, 15:27:58
Reply #2
burnin
Active Users
Posts: 1537
Re: opacity mask problem
idk and from description, undefined
so start by providing your test scene.
otherwise, does this look fine?
16bpc EXR used for opacity / Pixel values show no darkening
Edit:
& Here's version using jpg for opacity.
Edit2:
No PS here, I'm using GIMP ;)
«
Last Edit: 2021-05-01, 15:42:57 by burnin
»
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2021-05-01, 22:35:35
Reply #3
mitchino
Active Users
Posts: 86
Re: opacity mask problem
yours looks fine yes
my material is uv mapped to a slightly conical shape, could you try yours that way?
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2021-05-01, 22:36:47
Reply #4
mitchino
Active Users
Posts: 86
Re: opacity mask problem
looking at mine, I can't see the darkening on the inside of the pot shape at the back, only on the front faces
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2021-05-03, 12:56:32
Reply #5
mitchino
Active Users
Posts: 86
Re: opacity mask problem
I've attached a zip file with a c4d file and an opacity map.
I just cannot figure out why this is happening.
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2021-05-03, 12:58:06
Reply #6
mitchino
Active Users
Posts: 86
Re: opacity mask problem
How the file renders. The problem only visible on the cone.
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2021-05-03, 13:41:18
Reply #7
mitchino
Active Users
Posts: 86
Re: opacity mask problem
Here's the problem with a newly created texture. Same material applied to a sliced cylinder primitive using cylindrical projection, and a plane using flat projection.
The cylinder does not show the edge problem, the plane does.
In fact the problem shows up on every mesh I've tried except a cylinder.
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2021-05-04, 12:59:54
Reply #8
Beanzvision
Former Corona Team Member
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Posts: 3873
Bengamin
Re: opacity mask problem
Hi, what happens if you enable "Clip" in the opacity channel? ;)
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2021-05-04, 15:28:41
Reply #9
mitchino
Active Users
Posts: 86
Re: opacity mask problem
tried that - the soft edge is replaced by a hard edge
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2021-05-05, 18:37:33
Reply #10
burnin
Active Users
Posts: 1537
Re: opacity mask problem
My usual suspect is photoshop and how it handles things...
PS
attached file has a map made with GIMP
«
Last Edit: 2021-05-05, 18:57:23 by burnin
»
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2021-05-06, 09:58:34
Reply #11
mitchino
Active Users
Posts: 86
Re: opacity mask problem
I can't render that file as I don't have Corona 7 with the new Physical material installed.
To be honest I've given up on Corona for this job and switched back to Octane - I have a deadline to meet.
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2021-05-07, 10:46:51
Reply #12
burnin
Active Users
Posts: 1537
Re: opacity mask problem
Well, you could simply test in your scene using included texture & next time start with your specs...
Enjoy
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2021-05-09, 10:19:54
Reply #13
mitchino
Active Users
Posts: 86
Re: opacity mask problem
Could you use my c4d file showing the problem from earlier, and create a similar map in GIMP and see if it works on my cone mesh?
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Chaos Corona Forum
Chaos Corona for Cinema 4D
[C4D] General Discussion
opacity mask problem