Green screen test using Reflecmedia Litering, Keylight 2.0, please critique

N

Nicholas Natteau

Veteran
Please critique this footage I shot on my AF100 and composited using Reflecmedia Litering and then Keylight 2.0

http://www.vimeo.com/29286886

I'm trying to improve my chromakeying results. I posted this so I can learn from more experienced shooters and compositors and because I also believe others will find this useful.

Thanks in advance for any feedback.
 
You need to feather in your image. I still see a rim of highlights around your head.

Plus, always remember to light appropriately for your FG and BG plate to match.
 
Hi Doc, thanks very much for your help. For "feathering in the image", what tab should I be using?

Are you referring to Screen softness tab inside Keylight? Or applying a Matte Choker then Matte Feather in FCP?

Thanks.
 
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I believe it is choke in FCP. Basically, it shaves pixels down around your image. Make sure it is a soft choke though. If it is too hard, you will still have that hard edge around the FG footage that is the bane of greenscreen work. The key is to make the FG look like it belongs there, rather than just placed there. Basically you soften the edge, think a small eraser that gradiates the amount erased from center to edge. I use that trick in Photoshop all the time when pasting in objects from other photos. It only takes a little to make a big difference.

LOL, I know what it is, but I cannot remember the exact steps and filters to do it. Maybe one of our resident guru's will chime in and help me not look totally foolish.........
 
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Also light wrap, its where it spills a bit of the color of the background onto your subject, its a bit more complicated then a simple choke but it makes it look like the layers blend together in the same space rather then one layer sitting on top of another. I haven't done it by hand in FCP, but a quick google gave me this...
So what is lightwrap? Keying a blurred version of the background over the edges of the foreground with falloff into the foreground, using an apropriate composite mode.

So how do we do it? (Assuming you use a filter in fcp to pull the key.)

1. On the video track above your composite add a copy of the keyed foreground. (Just copy the clip you have keyed for your Composite. Set the display mode to matte.

2. Add another copy of the keyed foreground to the next videotrack (above) and set this to display matte as well. Change composite mode of this clip to Subtract. On this clip you can now use the Edge control softening to add suitable falloff into the foreground matte.

3. Nest the two clips. This nest is the matte for your edges.

4. Add a copy of your background above the "matte nest". Blur using whatever method and settings please you. Set composite mode to Travel Matte - luma. Now you have the blurred background composited over the edges of your composite with a falloff into the foreground.

5. Nest the "matte nest" and the blurred background. Change the composite mode of this nest to your liking. Usually Lighten is good, but you can experiment with Screen or anything else.
Click to expand...
 
The first thing I see a a shadow around the head and chair. It looks like you lit the talent from the front and he cast a shadow on the screen. Not good! Screen and talent should be lit separately. So the talent should not cast a shadow on the screen. It helps to have the screen far away from the talent. I think that shadow is what's causing the white edges.

Secondly, the color on the screen is uneven. Again lighting the screen to get it really even is important. When I look at the color values of the screen, most pixels have a lot of red and blue in them. It's best if it's pure green. Experiment with lighting the screen only, and see how pure of a green you can get.

The talent should be lit as if they were in the final composite. In other words, if it's outdoors on a cloudy day, then use a diffuse source. If the final composite has the sun on the actor's left shoulder, then the green screen footage should match. So in the last composite, when he's in a church, he should be lit as if he's really in that church.
 
stuckfootage said:
The first thing I see a a shadow around the head and chair. It looks like you lit the talent from the front and he cast a shadow on the screen. Not good! Screen and talent should be lit separately. So the talent should not cast a shadow on the screen. It helps to have the screen far away from the talent.
Click to expand...

True with traditional green screening, but just the opposite with a litering system such as the Reflecmedia LED system. Subject should be close to the screen and the littering system illuminates the screen.
 
Thanks, David, for pointing out my ignorance. (ooops) :embarasse

So if the subject were closer to the screen, the shadow ring would get smaller and the white ring in the key would disappear?

One question, though, why is the screen not very green? I see green values close to 1., but red and blue are both between .3 and .4. That's not ideal for the color-difference calculation.
 
I've been testing this for a couple of days.

Fill light 15 degree of camera to the right. 12-18" between reflecmedia screen and subject. about 10 feet between cam and reflecmedia screen.

camera on axis to screen and subject. best to zoom and light to about f4.2 or so.

That minimizes the halo, but of course both halo and shadow still might be very, very slightly visible in key.

Don't oversaturate or blow out the led lighting with the controller. 0 to +1 on mine work real well.
 
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