GL2 Greenscreen camera settings

[Aaron Nanto]

Hi all,

I've not seen this posted anywhere so I'm gonna ask - What are the optimal settings for the GL2 when shooting motion greenscreen work?

When I say "settings" I mean sharpness, color gain, setup level, etc. Can any of these things help out in getting a better key (esp. around the edges of my subject?)

Thanks for any help!

[Rob Lohman]

I've never shot greenscreen footage, but the most important
thing I hear is lighting the screen and seperating your forground
subjects from the background (to avoid spilling green on your
subjects).

I can imagine that you would not want ANY gain (so put it as
low as possible) which should not be a real problem if you light
the screen [just get enough light in there]. Setup level doesn't
have much to do with greenscreen but more with the latitude
you are working with [amount of contrast you can use] and
whether it must be TV safe.

Sharpness is an interesting question.... I would say not too much
but perhaps a notch more might help. It also might not though <g>

[Aaron Nanto]

Yah, I know about proper lighting (I have shot green before) but just mostly wanted to know if there was anything camera-wise to help out in keying.

Gain is a gimme, but I would assume that the sharpness is also something that can greatly alter the way the key will look. Well, I still need to do some tests, but just wanted to ask anyway.

[Mark Jefferson]

Hi Aaron,

This is a first-time post for me, so be gentle...

I've done quite a bit of green-screening, and this mini-tutorial will work with any video editing app that has layers (I use Adobe Premiere 6.5, but I don't see why this technique wouldn't work with any editing app). This info applies specifically for Adobe Premiere, however.

Most editing packaged that offer compositing functionality give less than satisfactory results. I've found a way to get very professional looking composits using only the editing package itself:

1. Shoot your green-screen footage. It's good to have a well lit green-screen, but even lighting is more important then brightness (You'll see why in a minute).

2. Capture your footage. Once you bring it into your editing app, load your footage on the first overlay track (layer 2 for Premiere)

3. Adjust the saturation levels of this video clip to 200% or better, especially for the green. This will really bring out the green background.

4. In the transparency settings, choose Chroma-Key from the drop down and use the eye-dropper to sample the green background, then choose "Mask Only" on the right side of the dialog. Close the Transparency window.

5. Sometimes, you will have to clean up parts of this mask, so if you need to do this, simply create a title and apply WHITE (all 3 colors set to 255) shapes to the imperfections in the white areas to get rid of any trouble spots.

5a. At this point, you can either create a virtual clip or render out this video into another clip. We'll be using this clip to create a "cookie-cutter" for our composited final video

6. Make a new project, load your clips, including the mask you just created, and put your plate footage (thats the background footage on which you will lay everything) on the first track (1a for Premiere)

7. Put the mask you just created on track 2 and change the transparency settings for this clip to "Alpha Channel".

8. Place your original greenscreen clip On track 3. Change the Hue so the clip is relatively close to the same color as your plate footage. This goes a long way towards eliminating a white or black line around your composited image

9. Put your original greenscreen clip on track 4, and change the opacity of this clip to around 70%. You may have to adjust the saturation to add a little color back into to image.

10. Render your image.

Sounds like a lot of work, but the results are worth it. No more fuzzy edges. No more green or blue tinted composits. Crisp, clear images. Who needs Ultimatte!

Sorry for such a long post, but this is the exact procedure I use, and I get better results this way then when I use AfterEffects.

Cheers,
Mark

[Aaron Nanto]

Welcome Mark! Thanks a lot for posting that mini-tutorial - I use Combustion 2 and Premiere, so I will try your method tonight to see what comes up...Sounds like it is very effective!

I did want to ask what camera you used on your green-screen shoots and if you captured directly to the camera or not. I know that you can get around this issue by capturing directly to the PC (uncompressed video) but I don't have the hardware available, so software manipulation is the only route for me at the moment.

[Mark Jefferson]

I have two camera's (both Canon's): A GL2 and a ZR20. Both are Firewire, so I import directly into my PCs. I use Scenalyzer Live! to import, saved me a boatload of trouble.

I actually developed this procedure for the ZR20, but it works really good with the GL2 also. If you're a Premiere user, you know how crappy the default method of green-screening works. Let me know what you think.

Cheers,
Mark

[Mark Jefferson]

Sorry, I made a mistake...(I'm a bonehead!)

On step 7, I said to set transparency to Alpha Channel, but I ment set it to Track Matte. Also, all your overlay tracks need to be set to track matte when you are doing your composit.

Sorry for the confusion. I wrote those instructions from memory, and since my memory doesn't do to well beyond five minutes...well you get the point. Now, what was I talking about...


Cheers,
Mark

[David Walding]

I was curious if frame movie mode would work better for green screen work since it is semi-progressive. I have shot some with my GL2 and when I was compositing I noticed that the interlacing seemed to give it some problems. You would think since frame is kinda like still pics it would give clearer and give better key's anyone tried it yet???

[Mark Jefferson]

Depending on if your greenscreen has a lot of motion, you may have to de-interlace your footage. I use my GL2 for just about everything anymore, and only use my ZR20 when I need a second camera. I only shoot in Frame-Movie mode. Some people say you only get about 320 vertical lines of resolution in this mode, but I don't notice any difference in resolution.

From a green-screen point-of-view, de-interlaced video is a lot easier to work with. Some Chroma-keyers like ZBig and Ultimatte can work directly with interlaced video, but they cost big bucks, and I'd have to do some fast talking to my wife to get permission to buy them!

Cheers,
Mark