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Partial transparency question

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Sam Steti

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Partial transparency question

PostTue Apr 18, 2017 8:40 am

Hi guys,

I'm on a project where a lot of keying is involved. I can do it in - at least - 3 different pieces of software, but I chose Primatte in Fusion to stick with other co-workers habits, and it's ok this way...

Now, I'd say 12 to 15% of last and recent green BG clips were not really well shot imho, and some are very important to us, leading to my question : we have to wipe out some parts of images where we see... the wall, and not the green bg :D And we cannot re-shoot, of course. I prefer a question now before falling into a never-ending polygon trick...

Although I have my own ideas, what would you use as a repeatable and specific workflow to make this part transparent before export in PR 4444 ?
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Sander de Regt

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Re: Partial transparency question

PostTue Apr 18, 2017 8:47 am

I don't know what you mean by the 'neverending polygon trick' but I think you need to create garbage mattes - and yes that probably will involve polygons - although you can also use circles, rectangles etc.
You can do this straight on the Primatte tool to do it all in one go.
Sander de Regt

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Sam Steti

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Re: Partial transparency question

PostTue Apr 18, 2017 10:23 am

Thx a lot for this advice. I thought some may suggest matte controls stuff etc, but this is quite logic...

Actually my OP came from the fact that a co-worker exported 4444 PR keyed in Primatte, but not only the green had to be erased and he lazily did not, resulting in clips like donuts :) : talents over transparent BG, BUT the whole scene surrounded by orange walls and stuff...
Then, before taking these clips back in fusion, I preferred asking.
Thx again.
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Sander de Regt

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Re: Partial transparency question

PostTue Apr 18, 2017 10:27 am

Matte control tools are also very useful for situations like these. I don't know the shots, but it's hardly ever a one button solution. It might even be useful to pre-garbage matte the footage, before feeding it into Primatte, so that Primatte will get footage that is as clean as possible.
Sander de Regt

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Sam Steti

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Re: Partial transparency question

PostTue Apr 18, 2017 10:34 am

Thank you again, this is exactly what I concluded too ("pre-garbage matte the footage, before feeding it into Primatte, so that Primatte will get footage that is as clean as possible"), to focus on potential fine-tuning.
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Sam Steti

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Re: Partial transparency question

PostMon Apr 24, 2017 8:39 am

Hi again...

Ok, let's summarize now that I've gone deeper in the project : I took the clips and tried things from scratch. At this point, I know some things for sure :

1/ The first problem is something's changed compared to the experience I had on Primatte in FCP7... but I don't know what so far. Let's put this aside (but I'm getting upset because it's waaaay not the 1st time I'm pulling a key and it's starting to look like 15+ years of experience are useless here, very frustrating) ;
2/ For 80% of these 40 clips, I'll have to deal with 2 colors to erase, not only the single green it was supposed to;
3/ I really want to do it in Fusion, for the workflow is ideal here (including Resolve). So far I didn't do it in Fusion Connect as I wanted to, I just loaded clips straight in Fusion.

What's good is these 2 colors are easy to isolate (green obviously but also unexpected orange) and don't occur in talents clothes; what's bad is that... I can't reach my goal so far, and moreover I don't get the reason why, except that I must have a problem with the garbage matte.

=> Let's get to it. Say the green key is done yet. Now I wanna fix the orange, which is the wall color that appears from time to time around the green (classic noobie angle mistake but lights were quite good on the other hand).
Actually I've come to the conclusion that the best way to do it is to isolate the orange wall part of the image in a (garbage) matte and then key this orange. The matte is important because you know, I cannot afford selecting this very color in the whole image for it's to close to talents skin.
I've also tried to feed one primatte node with another primatte node (green done) to work on each color separately, but in both case, it looks like (imho) the polygon mask is not taken into account (OR Primatte may not work with anything else than green and blue ? which would blow my mind honestly).

So roughly I have : Loader -> Primatte5 for green (done) output -> input Primatte5 for orange <- Polygon mask (in garbage matte input, selecting orange).

So what do you guys would do to fix that ? It should be sooo basic, I don't get it...
For example how would you pre-garbage matte ? I guess with a matte control, not a primatte, would you ? And is it possible to have multiple garbage matte on one single primatte node ?
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Sam Steti

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Re: Partial transparency question

PostTue Apr 25, 2017 8:23 am

Ok... I've understood the problem, and the difference with my long experience with Primatte 5 in FCP7.
The solution is not to pipe one Primatte node into another (tracks version could allow 2 filters on the same image), but to pipe them into the FG and the BG of a matte control node.
And above all, "post multiply image" was unticked for some reason, and that drove me crazy but it was just there :oops:

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