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Deep Glow on green screen footage causes transparency

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Noah Green
Deep Glow on green screen footage causes transparency
on May 6, 2019 at 9:53:11 am

When creating 3D projects I usually export the subject out of Cinema 4D in an mp4 format and with a green backplate. I then remove the green with Keylight, pre-comp, then apply deep glow. This sets the background to black so I check the 'Unmult' box to remove the BG, and my subject becomes transparent. I would apply the glow to an adjustment layer instead but then the whole project glows. I need a way of isolating the glow around the subject and not turning the black in the layer transparent.

Thanks
Noah Alexander Green
Hybrid Visuals


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Steve Brame
Re: Deep Glow on green screen footage causes transparency
on May 6, 2019 at 12:11:09 pm

I'm curious as to why you would export to MP4 with a green plate.

Steve Brame
creative illusions Productions


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Cassius Marques
Re: Deep Glow on green screen footage causes transparency
on May 6, 2019 at 1:05:21 pm

1- It should be applied to everything, just adjust the threshold to a more suitable value.

2- If by any reason you still don't want to. There's no way you can unmult the black from an image that has black in it without having it become transparent. Saving by masking.

I'm sure you know those two things, but I say it because the reason you're getting trouble is that your pipeline is all messed up. If you want just some parts to glow, isolate those directly from your renderer. When glows look real they usually happen everywhere that's bright.

I'd render stuff with alpha if possible, or luma mattes. Unmult works too but changing the blend mode to add is better when working with glows. Don't exaggerate values and don't forget to work in 32bpc.

Unless you post some pictures, what you're doing does work. But it may not be optimal so without seeing I can't say if you can tweak something or if you have to go back in the pipeline and render in another way.

Cassius Marques
http://www.zapfilmes.com


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Dave LaRonde
Re: Deep Glow on green screen footage causes transparency
on May 6, 2019 at 3:04:58 pm
Last Edited By Dave LaRonde on May 6, 2019 at 8:35:06 pm

Instead of making an mp4 you should make a movie in a codec that supports an alpha channel or an image sequence with an alpha channel. There would be no need for a chroma key or an iffy blend mode.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Andrew Somers
Re: Deep Glow on green screen footage causes transparency
on May 11, 2019 at 9:24:38 am
Last Edited By Andrew Somers on May 11, 2019 at 9:25:26 am

When creating 3D projects I usually export the subject out of Cinema 4D in an mp4 format and with a green backplate.


I read that sentence three times to make sure I wasn't missing something.

First, stop doing this. PLEASE. mp4 is approximately the worst format for an element you are going to do further work on. Second, putting in a green screen in said mp4 is beyond non-sensical. You're cutting off your nose to spite your face. mp4 is exactly the kind of format you never want for any kind of green screen work. YIKES! Please stop shooting yourself in the foot, eventually you're going to blow a hole in the floor and annoy your downstairs neighbors.

TRY THIS:
Export from C4D using ProRes4444 with an alpha channel. OR use an Avid DNxHD codec with an alpha. But please stop using mp4 with a rendered green bg! Doing just this change will solve your problem.

Andrew Somers
VFX & Title Supervisor
https://www.GeneralTitles.com


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