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Compositing problems (green screen)

Posted: Fri, 1st Aug 2008, 10:22am

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cottonproductions

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Hi,

I have been having problems with keying out my green screen correctly for a while now. I never seem to be able to get it looking perfect. I can get rid of the jaggads around the edges of my body but I get this flickering effect around the edges of me that I cant seem to stop no matter what I do. I feel that I am well lit enough that it shouldnt be much of a problem. I use two work lights placed on each side of the green screen (1000w each) and one 250w to light me.

I have a Sony Handycam Mini DV which I know probably is part of the problem due to low resolution. I keep all of my videos at 320x240 cause that is what the cam films at. I use uncompressed .AVI or .MOV and I have had the same problem with Compositelab Pro AND Keylight 1.2 in AE CS3.

I hate to admit it but I have seemed to have better luck with Keylight but still if its not my edges flickering, its something on my clothes like my jeans.

If anyone can help me I would be willing to post a link to download my raw footage so maybe someone who knows what they are doing can try keying it out and see if they have the same problem.

Thx,

Trea
Posted: Fri, 1st Aug 2008, 10:32am

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Simon K Jones

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cottonproductions wrote:

I have a Sony Handycam Mini DV which I know probably is part of the problem due to low resolution. I keep all of my videos at 320x240 cause that is what the cam films at.
Whaaaaaaat??

If it's a miniDV camera it definitely does not record video at 320x240. If the video you're capturing off the camera is that res, you're doing something seriously, seriously wrong and are losing massive amounts of data somewhere along the line.

What are you using to capture the footage? Are you connecting the camera to the computer via USB or firewire?
Posted: Fri, 1st Aug 2008, 10:37am

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Xcession

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I'd be very surprised if anyone can pull a better key with 320x240 resolution footage. Attempting to key footage of those dimensions is frankly ridiculous.

Imagine having an actor standing as tall as the video height, so their feet touch the bottom and their head touches the top. At 320x240, one pixel will account for several square inches on your actor's body. You can't get any more accurate than a pixel, so how is any software possibly meant to get a decent key, if one pixel accounts for several square inches of key subject?

Your problem is your footage.
Posted: Fri, 1st Aug 2008, 11:04am

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cottonproductions

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Tarn wrote:

cottonproductions wrote:

I have a Sony Handycam Mini DV which I know probably is part of the problem due to low resolution. I keep all of my videos at 320x240 cause that is what the cam films at.
Whaaaaaaat??

If it's a miniDV camera it definitely does not record video at 320x240. If the video you're capturing off the camera is that res, you're doing something seriously, seriously wrong and are losing massive amounts of data somewhere along the line.

What are you using to capture the footage? Are you connecting the camera to the computer via USB or firewire?
LOL!! Ok I PROBABLY AM doing something completely wrong then.. I'll let you tell me what the resolution is cause for some reason I read something one time then I thought it was 320x240.

This is my cam: http://www.sonystyle.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10551&storeId=10151&langId=-1&productId=11040247

Sony MiniDV Handycam DCR-HC32

The way I capture is through Sony Vegas 8 Platinum and I use USB. So I guess I need to know how to set the capture so that it gets it at the correct resolution. I FEEL A BREAK THROUGH COMING LOL
Posted: Fri, 1st Aug 2008, 11:10am

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Simon K Jones

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Use Firewire instead of USB and all your problems will be solved. smile
Posted: Fri, 1st Aug 2008, 11:18am

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cottonproductions

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Tarn wrote:

Use Firewire instead of USB and all your problems will be solved. smile
Ok.. I assume you mean the DV iLink cable that you can buy for this camera when you say firewire. Can you look at the link and tell me what the resolution of this camera actually is? I just tried changing my settings in vegas to NTSC (720x480 default) and recaptured some footage but when I looked at the footage properties afterwards it still says 320x240x24.
Posted: Fri, 1st Aug 2008, 11:25am

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Simon K Jones

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Yeah, capturing via USB will reduce the quality.

Here's some info on firewire:

http://en.wikipedia.org/wiki/FireWire

It's the standard method for transferring miniDV and HDV footage from camera to computer. If you weren't provided with one with your camera, or at least advised to get one when purchasing, then it's pretty poor service.
Posted: Fri, 1st Aug 2008, 11:33am

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cottonproductions

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Tarn wrote:

Yeah, capturing via USB will reduce the quality.

Here's some info on firewire:

http://en.wikipedia.org/wiki/FireWire

It's the standard method for transferring miniDV and HDV footage from camera to computer. If you weren't provided with one with your camera, or at least advised to get one when purchasing, then it's pretty poor service.
Ok awesome! Yeah poor service definately. I can't beleive all this time I have been losing my quality no wonder I cant get good keys. I will have to go out and get that cable ASAP I need a 4pin to 6pin I think. I'll let you know when I do and how it turns out in this forum.
Posted: Tue, 5th Aug 2008, 8:17am

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cottonproductions

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TARN!! Your the best... I got the firewire now and it makes ALL the difference.. I can't beleive all this time I was using USB and getting 320x240 .. now I get 720x480 and it looks so much better! Thanks for all of your help in these forums you definately make like alot easier for alot of us.. lol.

Trea Cotton
Cotton Productions
Posted: Tue, 5th Aug 2008, 8:18am

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Simon K Jones

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Glad to be of help! Happy filmmaking. smile
Posted: Tue, 5th Aug 2008, 6:47pm

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Bryan M Block

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Also, in Vegas there are some things that can help you- you can use a color corrector effect before the chromakey effect to work with your greens- adding a bit of contrast etc. might help seperate the subject from the green- and don't forget to use the ChromaBlur to soften the keying edges. All of these effects are also keyframable as well, so if things get weird you can adjust the settings over time. If things get really bad, you can use the masking features in the Pan/Crop dialogue for your clip to completely cut out the background, although that would be a bit time consuming.

-B
Posted: Wed, 6th Aug 2008, 4:33am

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cottonproductions

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Bryan M Block wrote:

Also, in Vegas there are some things that can help you- you can use a color corrector effect before the chromakey effect to work with your greens- adding a bit of contrast etc. might help seperate the subject from the green- and don't forget to use the ChromaBlur to soften the keying edges. All of these effects are also keyframable as well, so if things get weird you can adjust the settings over time. If things get really bad, you can use the masking features in the Pan/Crop dialogue for your clip to completely cut out the background, although that would be a bit time consuming.

-B
Yes, I get so caught up in the features of all of my other effects programs that I sometimes forget how many different features Vegas has. I will try that the next time I capture, I need all the help I can get with my compositing but its coming along alot better now that I got my resolution problems fixed.
Posted: Wed, 6th Aug 2008, 8:25am

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Simon K Jones

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Just thought I'd mention that you can do all of those things in CompositeLab, too. smile
Posted: Wed, 6th Aug 2008, 9:13am

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Mellifluous

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Lol, I shouldn't really but this topic is pretty hilarious. How long have you been working with video with that quality?

Glad to you're on your way to righting yourself though smile
Posted: Wed, 6th Aug 2008, 1:56pm

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cottonproductions

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Mellifluous wrote:

Lol, I shouldn't really but this topic is pretty hilarious. How long have you been working with video with that quality?

Glad to you're on your way to righting yourself though smile
I guess for about a year but only really been compositing about half that time.
Posted: Wed, 6th Aug 2008, 2:36pm

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Avenging Eagle

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At least you were working with digital. My first camera was an old 8mm Canon UC2000. It DID only capture at 320x240...interlaced. Trying the chromakey that footage was near enough impossible.

Happy compositing!

AE
Posted: Sun, 10th Aug 2008, 1:47am

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cottonproductions

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Hi everyone.. just an update on my green screening problems. I have noticed now that I am using firewire that when I capture my video in Vegas 8, it is interlaced (lower field first.) What I used to do with my USB captures is render the capture out as progressive and I never noticed any interlacing. Now that I am getting all my resolution, rendering the capture as progressive with no deinterlacing is not working.

So I found a way to get rid of it using the deinterlacing BLEND fields method along with square pixels. The field order is still set to progressive though. Should it be lower field first or should I leave it progressive? BTW this footage is going to be watched on computer not TV.

I am still seeing some artifacts around my body when keying that are hard to get rid of. I think PART of the problem according to Axeman (from reading other forums) is that instead of being 5-6 feet from the green screen, I was about 3 feet from it. In the future, I will make sure to stand further from the green screen and just scale it down while compositing but for the mean time, what can I do to help with the artifacting?

I am using blur and spill supression. I also only notice it in my clips that are close ups rather than the scaled down shots. I guess what I am wondering is.. is the raw interlaced footage causing more problems while I key. If so, I could render the video capture out the the deinterlacing turned on and THEN key if it is better that way.

Hope I didn't confuse everyone cause I think I confused myself lol.
Posted: Sun, 10th Aug 2008, 2:15am

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Axeman

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Interlacing will not cause any problems at all with the key, as long as it is captured properly. You may be able to impprove your results by adjusting your settings a bit in your key, using a different kind of key, or using more than one key on the footage. Are you currently using any Key Grading? Some adjustments there could greatly help as well. If you can post a sample of the footage in question, we may be able to provide more specific guidance as to where to make adjustments, or what key settings to use.
Posted: Sun, 10th Aug 2008, 3:48am

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cottonproductions

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Glad to see you in here Axeman,

I am uploading a few seconds of my raw footage for the shot I am talking about. I did it uncompressed so that it wouldnt loose any quality and the only way I could make it less than 200mb was to make it a few seconds long but the part where I am standing, facing the green screen is where the artifacts are showing so you should be able to see it. I know the first thing your going to say is that I am too close to the screen cause I notice it now after reading some of your other posts and I am casting some shadows. But whatever we can do for the time being would be great!



Here is my best attempt at the final shot, I uploaded it to youtube for you: http://www.youtube.com/watch?v=B666YQ0CVMA


Here is a few secs of the raw uncompressed footage: http://ia311229.us.archive.org/2/items/GreenScreen_680/test_fxhome.avi
Posted: Sun, 10th Aug 2008, 6:11am

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Axeman

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Right, I'm downloading the clip now. Watching the Youtube composite, it looks kinda like you have added a slight blur to the key. I could be wrong. In most cases, this does more harm than good, as it tends to blend the greenscreen with the actor along the edges, which Spill Suppression then turns into a grey line. If there isn't a blur, disregard that. I may have more input once I have a chance to look at the original footage.
Posted: Sun, 10th Aug 2008, 6:54am

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Axeman

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OK, while the greenscreen is fairly evenly lit, and shadows don't seem to be a problem, the entire setup could benefit from more light. The problem caused by being too close isn't so much shadows being cast, but spill from the backdrop. In your clip, it is most noticeable on the pants. There is a fairly obvious green cast to the pantlegs along the edges, especially along the left side which is more in the shadows. This is the "spill" that spill suppression can help with, but in this case, it is a bit severe. Based on the composition of the youtube clip, I assume that you noticed that the pants were the biggest problem area.

I actually think the key you pulled is nearly as good as you will get from that particular footage. One other tip you can try; rather than using a blur on the footage, right-click the thumbnail in the media inspector, select "Media properties..." and adjust the UV blur settings. You can try shifting it both ways to see if you can improve your edges.

Sorry I couldn't be of much help, but maybe someone else can get a better key. I played with the footage for a bit and couldn't really improve on the results you had already achieved. More separation betwen your greeenscreen and your actor will certainly help though, as would having more light.
Posted: Sun, 10th Aug 2008, 7:05am

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cottonproductions

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Hey thanks for the help Axeman! I figured that my footage was probably too bad to do anymore with than I already had on the youtube clip. I am lighting my green screen with two 1000 watt work lights (1 on each side that actually has two lights on each stand) and I have a 250 watt work light in front of me but to an angle. I am not sure what other steps to take to light things up better other than buying one of those expensive light kits with soft boxes which I cant afford just yet.

But based on what you said about the spill, I think that is my main problem and that maybe if I back up from the screen another 4 feet or so, it will work out better in the future.

I know you said you got the green line bad around my pants but in my youtube clip, I cut out the bottom half of my body so the main area I notice that gives me trouble in this particular clip is my shoulders.

Did you get the same flicker that I did?

My pants were a slight problem in another shot that I composited where I was sitting down but I managed to get it somewhat looking good.
Posted: Mon, 11th Aug 2008, 8:13am

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Simon K Jones

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You probably shouldn't deinterlace until you've finished the project. You can then deinterlace it for computer viewing. However, deinterlacing during the editing process will only reduce the quality, and potentially make compositing more difficult. So keep the footage interlaced and in its original state during post-production, if possible.
Posted: Mon, 11th Aug 2008, 10:05pm

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Bryan M Block

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You could always use diffusion and top-light the greenscreen so you get less shadows, but that can get really tricky without appropriate grippage...
Posted: Mon, 11th Aug 2008, 11:29pm

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Axeman

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I was guessing that you cropped out the pants in that shot, because of the keying difficulties.

Setting up some sort of diffusion in front of the lights may enable you to get them closer to the screen without creating hot spots. I'm surprised though, it seems like with the lighting you described you should have plenty.

And yeah, even with the exact same lighting setup, getting a few feet farther away from the screen should help tremendously.
Posted: Tue, 12th Aug 2008, 2:25am

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cottonproductions

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Tarn wrote:

You probably shouldn't deinterlace until you've finished the project. You can then deinterlace it for computer viewing. However, deinterlacing during the editing process will only reduce the quality, and potentially make compositing more difficult. So keep the footage interlaced and in its original state during post-production, if possible.
Thanks I will try to keep it interlaced in all of my programs until I get it into vegas for the final render. Anybody have any opinion on using those "dryer sheets" to cover the works lights and achieve some diffusion? I know that get really hot so not sure if that is a good idea or not just trying to come up with every little trick I can for lighting until I can get a professional lighting kit.

Also Tarn, if you get a chance can you review my demo reel I uploaded in the Box Office? smile Thx
Posted: Tue, 12th Aug 2008, 3:23am

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Axeman

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Here is a gel kit of some diffusion filters, 10"x12", designed for using on hot lights. Last one in the list. Only $16. It is a kit, but it doesn't say exactly how many gels are included. A quick call to the seller could probably answer that though. When it comes to working in the extreme heat those lamps put off, you are much better off playing it safe and using something that won't melt or burst into flames. Even so, finding a way to mount it at a bit of a distance from the light is still a good idea, to prevent warping. Its actually fairly standard on set to use wooden clothespins to hold gels, in lieu of a real frame. They call then C47's.