I've got the green screen blues

L

LukeWilbanks

Hi,

I'm in production for a music video I decided to do for fun. Most of my shots involve using a green screen. My plan was to use Final Cut Pro 4.5 to key in the plates. I thought it would go over really well in editing since I lit the screen and foreground so well. Unfortunately, that's not the case. All the edges of my foreground subject have become wavey lines. Is final cut pro not very good for chroma keys or am I doing something wrong? I have already checked what the manual says about keying but no quality differences when I follow their directions.

Would it be better for me to use Shake or After Effects?

Thanks for your input,

Luke
 
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I have access to Keylight and Primatte - two industry leading keyers. I could try running the files through my system if you would like.

Shake is Mac only and AE operates under both. Both are rather expensive for a single job though - unless you are getting payed well :).
 
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Shaw said:
I have access to Keylight and Primatte - two industry leading keyers. I could try running the files through my system if you would like.
Click to expand...

Hey Shaw,

That would be awesome if you could throw my stuff through your system. I wouldn't burden you with all my green screen shots. Maybe I could give you a 5 or 10 second clip. If it turns out that the problem is with my lighting I can re-shoot. Otherwise, I'll buy whatever software I need to get decent compositions. Would the alpha layer transfer over, or would I also have to give you my plates?

Thanks a lot,

Luke
 
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Honestly, I'm not sure :). A 10 second clip or so sounds great. That way we can see if this will work and what output would require. I'll send you a PM.
 
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Mmm yes, Ultra can produce nice results. Some keyers work best in some situations while others work better in others. It's interesting to see actually though it's damn annoying as I feel the need to acquire all of them just in case!

Did you shoot this footage with a single chip camera? It is indeed harder to key than it should be! Maybe I'm just spoiled with my DVX. The lighting is quite good but the green may be a little too light.
 
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The camera we were forced to use was a 3ccd consumer level Panasonic camera. I don't know the model # off hand.

I too have never had so much trouble with a key. The process is normally pretty smooth for me.

If anyone else would like to try their hand at this composition, there is a 9 second clip at http://www.lukewilbanks.com/shorttermfiles/greenscreen.mov.zip

For future reference, what materials do you folks use for green screens? There are a lot of different kinds of products out there and I'd like to invest in something that will pull its own weight. I'm within weeks of buying an XL2 or a dvx. That should greatly improve my capture quality.

Right now, I'm using a canvas material and I'm lighting it with halogen. Would I get a better effect lighting with flourescent?

Thanks,

N
 
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Spaulovich made a great greenscreen guide, found here. :yes:

_______

Looking at your clip, one can see with the naked eye the variances in lighting on the greenscreen. It's a lot darker on the left side, than the right.

If you use something like After Effects, you can add multiple chroma-keys to the same clip. That can be useful when you have colour changes. It's much more precise than lessening the sensitivity of a single key.

_______

You're also shooting through glass... I'm not sure if the camera is in or out of the car, but regardless, there's at least one (possibly two) layer of glass in the way which can do odd things to light, no matter how well lit your screen is.

That happened to the good folks at Other Side Cinema, in their last film.

Hope some of that was useful. :)
 
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Thanks Zen,

I didn't imagine that a pane of glass could mess the key up so bad. I'll definetely keep that in mind for the future.

The camera was inside the car mounted to the dash board and had a wide-angle lens.

That was an awesome guide. Thanks for leading me there.

Luke
 
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SPaulovich said:
I've got a copy of Serious Magic ULTRA - the ultimate keying software. I'll try running a 10 second clip through for you to see how it looks.
Click to expand...

Okay - ULTRA handled the keying with no problem. Here's the result

A couple of notes:

* The source input was MOV - it would probably look better working with raw AVI.
* I used a static background, it would look more convincing with a clip behind it.
* The result is squeezed down to 512K Streaming MOV (< 500KB)
 
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Thanks Steve,

That is an excellent result. I am going to start thinking about a third party keying software. I guess Final Cut Pro isn't cut out for the meaty compositing techniques. I'd like to find something that will be compatible with FCP.

Thanks again,

Luke
 
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Lefteye, I can upload my results and PM a link to you if you wish. Ultra is giving a better key though so I would definitely suggest going with it in this case. Primatte did relatively well but not nearly well enough. It makes me wonder why this footage was so problematic for chroma keyers (like you and I used). It may be because the backdrop was far too similar in tonality and luminance to the rest of the scene. I know I've pulled so great keys using Primatte in the past so I'm a bit disappointed with the results this time.
 
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Hi Shaw, I am interested in seeing your results, regardless of how they turned out- that is, if you have the time/energy/will to upload the file.

What should I have done differently to offset the tonality of the screen? I understand the luminescence issue- In the future I will use flourescent lighting as opposed to halogen. Is tonality a function of luminescence?

Thanks for your efforts,

Luke
 
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From my experience, Ultimatte's AdvantEdge is pretty damn good at keying. After Effects built in Keyer is good too but it takes a lot of getting use to.

The problem with keying miniDV footage has everything to do with the 4:1:1 color sampling and the 5:1 compression. No matter how well lit your screen is, you're going to have a fringe to deal with. The easiest way to handle the problem is to choke the matte but if you choke it too much, the image that you're superimposing could look like the edges are wavey. After effects has a setting under its choke utility that allows you to smooth the edges out before choking them. This does a lot to take away the wavey thing..

Check out some of the blue/green screen clips on my site: http://www.morphicmotion.com/

when you get there, look for "spaceship fly by" and "clones" Both clips made use of a blue screen.
 
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Ai, Ultimatte is great because it attempts to reconstruct the missing chrominance. I was, in fact, using AE (with Primatte) to attempt the key. Didn't get very good results this time though I have gotten perfectly decent keys before. Strange how this piece of footage is so tricky!

I'm uploading a .mov of the composite. I'll PM you a link when it finishes (don't have to bandwidth for lots o' downloads). :)
 
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