Green Screen

[Don Greening]

I guess the first question that needs to be asked is whether or not you had the picture gain on the camera cranked up. There is a direct relationship with pixel noise and the picture gain setting. Shoot with the lowest gain setting you can. Some cameras can be set with a minus gain setting (such as -3) for the least amount of pixel noise. Of course, you have to throw more light on the green screen and the talent to compensate. for the lower gain setting.

– Don

[Jeremy Fonkert]

Thanks. The gain was as low as I could set it. I forgot to mention that it is the cinealta version of the Sony xdcam.

[Craig Seeman]

I’ll second what Don says. -3 or 0db max for green screen. Noise is a bad thing to battle against when keying.

Also, given that XDCAM is generally 4:2:0, shooting progressive can key a bit better than interlace. Of course the PDW-700 can shoot 4:2:2 so that’s an exception (for the moment).

I’ve heard some will dial down detail and dial up frequency in the picture profile to help soften edges too.

[Clint Fleckenstein]

I just got done keying several dozen clips shot in a cramped office with a portable blue screen and minimal lighting. They’re all turning out fantastic. Don’t be disheartened if you don’t get the results you want right away.

First off, since you’re in After Effects, it’s important that you use the Keylight keyer that was included with AE. If you don’t have that effect installed, install it from your original discs.

Second, don’t be afraid to hit the “reset” button on your key settings and start from scratch. Sometimes you just need to wipe the slate clean and take a new approach.

Third, don’t expect magic. Sometimes there will be areas that simply will NOT key properly and will have to be done with a mask. Other times you will use the eyedropper to select your background color and instantly have a key that’s almost finished quality.

In Keylight, one quick and dirty way to get close to where you want your key is to clip the matte black as high as you can, the white as low as you can, then pre-blur and soften your matte edges just a hair so they don’t look unnaturally hard. This will take out the garbage noise in your background area, yet fill out the area you want to remain keyed. From there you’re basically refining the edge.

I came to XDCAM EX from keying DV footage, so working with EX green screen footage is like being a kid in a candy store by comparison!

Cf

[Larry]

Was it blue screen? Or green screen you were shooting with the XDCAM EX? I would think blue screen would be a bit of an issue with the EX.

Larry Warner
LWP, Inc.
http://www.lwp.com

[Jeremy Fonkert]

It was a green screen. The noise issue was with the subject, her darks on her clothing were blocky. Have used the same lighting set up for beta for years and have not had this problem.

[Sean Morton]

Hey There.

i am having the same problem.. did you find a solution..
in order to fix it “for now” i used remove grain to
get it looking a little better.. would like to have shot
it properly.

Help???

[Jeremy Fonkert]

Sean,

I will talk with our other editor, but if I recall he just kept playing with the key light settings in AE and had to do some masking. It turned out fine but when the subject moved quickly it became time consuming. I did do some testing with the camera and tried the two settings sony gave us when we had training. Niether of them were as good as the default carmea settings when it came to keying. Good luck and will post again if I find anything different.

[Curt Pair]

Jeremy,

I will tell you honestly that LIGHTING is the absolute “key” (no pun intended) in a successful chroma key shoot.

I’ll tell you that I have a friend who works at Lucas Arts… he was visiting once, saw how we “keyed…” laughed at me and then shared some amazing advice and knowledge! NOW… I’m hired all the time to go back and RE SHOOT for those who have screwed it up! I actually go to the length of telling clients if they can’t key our footage in three mouse clicks or less in Keylight, cleanly, we’ll give it to them for free! That’s how solid the methodology is! (often, I only have to click once in Keylight to get the key, and it’s incredible! Time to export!)

I will tell you that you MUST use a waveform monitor to light your subject. I refuse to give away ALL of my techinques in this forum, after all, I want to stay employed, but if you wish to contact me directly, I’d be happy to share what I have learned over the years.

It is critical to KNOW what platform will be editing your footage, by that I mean, Premiere, Avid, FCP, Edius, Vegas, Quantel, etc. Each have an optimum range for key illumination. I have found a great “mid-range” of lighting the key background somewhere between 68-72 IRE.

I’d frame the shot, at it’s WIDEST point, and remove the talent. Then I would light the background. Keep an eye on your vector scope! You are trying to create a SOLID, thin line, as straight as possible in the 68-72 IRE range… if that line has some “bulk” to it, your lighting is NOT even! You can pan a light, add a light what have you to rectify the problem.

Typically, in the past, and it’s slightly modified now, for head and shoulder shots, I use a Westcott TD5 Spider light, in softboxes with grids for the key and fill, a 1K Mole, fully flooded with 216 gel, on each side for the background, and then, depending on the person or persons, I will use either Mole 150s or Dedo Lights as a hair/shoulder light.

Here’s the important tip: Once you have the background exposed properly and have a thin, flat line between 68-72 ire, DO NOT TOUCH THE IRIS again! This is VERY IMPORTANT!

To light the talent, walk lights in closer or move them back to light by eye, or what you like on your monitor. If you can’t get what you want, don’t touch the iris, change instruments… often people of darker complexions need more lighting… we do a lot of this type of shooting with professional athletes… I will have a 1K Mole in a softbox standing by for the extra punch, if necessary.

My VERY FIRST “PAID” SHOOT with my F350 XD Cam HD camera was a green screen shoot for NASCAR! I was nervous beyond belief… I’d NEVER tried keying with this camera… we shot 130 driver “tag line” type things with various stars of NASCAR… (in a single day! The clips were between 10-30 seconds each.) Using the Lucas method, I was able to take the footage to the office, copy the disc to the system and be in After Effects inside a half an hour… I then AUTOMATED the key process by opening the MXF file, applied Keylight, clicking in a corner, removing the green, and saving the file with alpha. NASCAR wanted the files uploaded to their server… they gave me an FTP site. I set up the automation and went to dinner… when I came back, all the keying was done. I started uploading to their server…. they had everything by noon the next day! They had given me 14 days to complete the project… you can imagine how impressed they were! I was able to pull this off for NASCAR with a single click in Keylight. I checked the matte first before automating.

Chroma Keying is all set up. I won’t kid you… I do have a few more “secrets” but a man has to keep a few things to himself! This was presented to me by someone who does this full time at Lucas Arts, and it worked fine for me for years… So much so that we came behind many in the pro sports world to reshoot things for national broadcasters and arenas needing chroma footage. When Star Wars Episode 2 came out, Luscas modified the methodology, we now emplore that and it works even better. I have shared that with folks, but they get mad at me when they don’t get the same results… Oh the padawans…

Curt Pair
Picture This Productions
Sony ICE Team
F900/F350/700/EX1/EX3/D790/D600
Adobe Premiere Pro CS3 HD/Matrox
Phoenix, AZ

[Ronn Trevino]

Curt
Great Info thanks.. I love keylight it makes up for a lot of slop, however lighting is key. We need to get a portable waveform monitor to work on your method. I do have a question though. You mentioned importing .mxf files into after effects. We have an XD-cam and as much as I’ve tried AE CS3 doesnt support MXF files at least not ours. So how did you do it?
Have you used On-location does this have a waveform that would allow for the same type of control? I honestly havent used it but the idea just popped into my head.

its all fun and games till some one loses a match frame… – Me