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Check out this busted key - what are we doing wrong?

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Travis Turner
Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 3:57:08 pm

We're shooting on an HDX 900 to DVCPro HD tape , 66 min at 9 microns - 720p 59.94, 30p camera mode. I'm trying to pull a key on this footage using After Effects CS5 with keylight. We keep getting these horrendous grid type artifacts that show up around the key. They look like chroma sub sampling regions but I'm not completely sure that's what it is - and I'm attaching a grab of what I'm seeing. Anybody ever run into this before? So far we can't find a workaround. The Avid is able to pull a decent key but after effects keeps giving us these results so I'm totally confused
thanks





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Nick Rosier
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 4:14:40 pm

I came across this recently - for me I simply had to change the 'interpret footage' settings. Nothing to do with keylight as far as I'm aware. Aspect ratio correction?


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Philippe Lessard
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 6:25:23 pm

First:There a button under your composition window, its a little box with a double tiped arrow over it, click on it, you should see your footage a litte scewed, but with no artifact.

Second:Have you change your footage interpretation? Because your dvcpro hd is not square pixel, but if you have interpreted it square pixel after making a comp by dragging your clip on the make new comp button (on the bottom of the project window), then you have a problem because your comp is not in square pixel but your clip is!I dont know what is your ouput setting, but if you work in dvc pro hd and your output/comp setting is dcvpro hd, you have to use the toggle pixel aspect ratio correction button in order to see your footage in the proper aspect ratio, like i writed it never look good in after effects (its just a preview mode) in any other aspect then square pixel, but you render will be ok.

Hope this help


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Dave LaRonde
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 4:19:36 pm

Two things come to mind:

As I look at the Keylight settings, it appears that you've only used the eyedropper. There are a BUNCH of parameters in Keylight, and it isn't the kind of plugin you can use intuitively. If this is your first foray into using it, I STRONGLY recommend looking at tutorials here on the COW, and it would not hurt one bit to download the Keylight tutorial from The Foundry's web site.

It would also appear that you're scaling the footage up. Yes, I see that the comp window is at 200%, but I also see the footage highlighted in the project window, and your subject is really tiny in that shot, which is why I think you're scaling the footage up. In that case, Keylight's done a bang-up so far just with the eyedropper.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Nick Rosier
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 4:21:59 pm

Don't think keylight is the problem here - I had the exact same vertical lines in a piece of footage without any effects applied.


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Travis Turner
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 4:27:01 pm

Indeed - thanks for the replies guys, I don't think it's a keylight thing either. I'm seeing the same artifacting in keylight as I am in Boris Chroma key - I've tried adjusting pixel aspect ratios and switching to 16 bit mode in the project , none of which has worked - so you can see why we're at a loss



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Dave LaRonde
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 4:45:35 pm

Thought about using a garbage matte so you're not keying an entire HD screen, which may have widely-varying shades of green? Especially a really tight garbage matte? Here's how it's done:

http://podcasts.creativecow.net/after-effects-tutorials-podcast/super-tight...

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Philippe Lessard
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 5:31:17 pm

For me it's look like just to be the "toggle pixel aspect ratio correction" preview in after effect, since dvcpro hd is not square pixel you have to use this preview mode to see the proper ratio in after effect on your square pixel computer screen, but is never look good!

Hope this help


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Philippe Lessard
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 5:44:15 pm

Sorry, just to be clear, if the toggle aspect ratio correction preview mode is the problem, then you have no problem, just render your comp and it should be ok.


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Philippe Lessard
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 6:43:28 pm

You surely have a wrong aspect ratio, because your talent is scewed horizontaly and your toggle aspect ratio correction button is set to off!Your clip must be scaled or your interpretation footage vs your comp setting is wrong.

Do it from scratch by dragging your footage on the make new comp button at the bottom of the project window, then put keylight on your footage...etc and try the toggle aspect ratio correction button to see what it do.


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Travis Turner
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 6:54:16 pm

We're actually doing just that. I dragged these clips on to the make comp button to begin with - toggle aspect ratio button doesnt help either - so far its still a mystery



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Travis Turner
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 6:52:54 pm

Yea - we looked into pixel aspect ratio too but that isn't it either. I'm bringing the clips in square pixel but i've tried manually using the DVCpro presets with the 1.33 p.a.r. and that didnt do anything to help - I'm attaching another image to maybe better show what we're dealing with - it's this "grid" I'm calling it that's carving into the key - you can see it best on her shoulders in this shot where there's about a one pixel series of lines going into her shoulder on the left and extending from it on the right - neither of these markers appear on the unkeyed footage - so strange




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Philippe Lessard
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 7:03:11 pm

Well is maybe just a chroma issue, since you work in dvc pro and dvc pro is 4:1:1, dv is maybe the worst codec for keying!!

Try a chroma blur before keylight with low value, it should help


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Kevin Camp
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 7:25:53 pm

it does look like there is a par issue... but there are several places things could have gone wrong.

you shot to dvcprohd 720p60 in 30p mode... dvcprohd 720 is natively 960x720 with a 1.33 par, but these files were captured form tape... so they could have been captured as square px (1280x720) in avid and could have been captured as a different codec.

then they could have been exported from avid in a different par and codec then they were captured with.

so there are many places that where this issue may have occurred. open the bad file that you have in ae, in a quicktime player and see if you see those vertical artifacts in qt. if you don't then the problem is with ae somewhere, if you do, then the problem is before ae, either capture or export from avid...

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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Travis Turner
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 7:41:44 pm

That's the thing - you can turn keylight off and you can't see the "grid". I've tried all manner of par combinations but I still think this looks like a chroma sampling thing - which would mean you shouldnt see it in unkeyed footage anyway - I just didn't know if there was something obvious I'm missing



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Dave LaRonde
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 7:55:31 pm

You're seeing this problem using two different keyers. So I'm inclined to agree with Kevin: it's more of a footage problem than it is a keyer shortcoming.

Double-check the footage in Avid -- is it still in the DVCPro HD codec? Something else? Was it transcoded along the way into AE? Did the pixel aspect ratios get messed up en route to AE?

It's kind of obvious, but the closer you can stay to DVCPro HD and 960x720 with a 1.33 ratio -- which is how it was recorded in-camera -- the better off you'll be.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Philippe Lessard
Re: Check out this busted key - what are we doing wrong?
on Sep 10, 2010 at 7:23:34 pm

It definitly look like a chroma issue, since you didnt see the "grid" in source footage it must be chroma.
Like i writed, try using a chroma blur third party plugin9(because AE didnt have one).

Or if your have the hardware, capture your footage from HD SDI output or event SD(if your ouput doest need to be hd), because your camera HDX900 have one and you'll be able to capture 4:2:2 with a lot better chroma and overall picture quality!

Hope this help


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