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View Full Version : Live set mattes and cameras



nedb
05-11-2009, 09:34 AM
I am using Panasonic AG-DVX100 cameras with Live Set. I light the chroma key set evenly. The 'talent' is lit with two backlights, a key (softbox) and the side fill is a bounce card. The 'talent' is 8 feet away from the green muslin.

I have been unable to achieve a satisfactory key. I end up with a green edge glow that no amount of tinkering will get rid of. After reading many things on the web about chroma keying and mini DV cameras, I am convinced that the problem is the camera.

Any ideas or experiences would be appreciated.

Paul Lara
05-11-2009, 10:11 AM
You didn't say how much illumination you are throwing at your green wall.
Start by turning your key wall illumination off. If you immediately pull in improved key, then it is possible that you are over-lighting the wall, with much of that bouncing back on your talent.

I have pulled a clean key without any lights dedicated to the wall, relying only on the spill from the key and fill soft lights.

Let us know how it goes.

billmi
05-11-2009, 12:06 PM
After reading many things on the web about chroma keying and mini DV cameras, I am convinced that the problem is the camera.


What software are you running the LiveSet in (Tricaster Broadcast, VT[5], etc.)

How are you getting the video from the camera into the computer/software?

If you are recording to DV tape, or sending the signal via firewire, the compression involved will be throwing away enough color information that keying cleanly can become difficult - the most common artifact this causes is blockiness on the right hand side of the subject.

Sending the video in by analog, the signal quality available to key from improves as you move from composite, to Y/C to component connection formats.

nedb
05-11-2009, 01:55 PM
Billml:

I am using LiveSet on a TriCaster Studio and the Panasonic AG-DVX100B and a AGDVX100p.

Both cameras are connected via S-Video cable.

nedb
05-11-2009, 01:56 PM
Paul:
I have the wall lit evenly 1 stop less than the talent.

billmi
05-11-2009, 02:34 PM
With that set-up, I would not expect the DV to be an issue, since you're not recording to the DV format, and sending the video Y/C Tricaster/VT systems are able to pull a pretty clean key, bonus points for using 3 chip cameras.

The distance from talent to the screen is good for reducing splash on the talent - and the set up sounds good.

Perhaps a screen shot of the pre-keyed shot might show something that someone would recognize as a source of the problem.

joseburgos
05-12-2009, 10:32 AM
Yes there seems to be more to this as I get a great key with 6' of distance from the subject and I illuminate the green screen separate from the subject as well.
And like Bill wrote, the DV issues you read about is for post production methods where the compression of the DV format come into play. You are not using DV as Bill has wrote. You are using S-Video. The camera only goes to the DV format when you record to tape or pass your signal out through the 1394 port.

I would speculate the green screen is reflecting light more than normal and Paul's suggestion to lower the amount of light on it seems like a good place to start. That and a image like Bill suggested so we can see what you see.

Oh, just to be sure, you have tried adjusting the LiveMatte controls to see if they help, right? Rather state the obvious before we chase our tail ;)

spaceball
06-14-2009, 09:42 PM
I've heard people say you can try various tricks like:

strong white backlight (even hide the backlight behind talent) to help separate the edge.

Using magenta / red / warm gels on backlights and or sidelights
Magenta is the opposite of green, so this would figure as it would take any green out of your edges making for a better key, BUT... while this may work for an after effects comp where you can grade out the wacky backlight colours you may not have that much control in Tricaster...

Possibly you could try warm gels over all your lights - you could then colour balance back to neutral colour temperature using the Tricaster controls.

I've worked on various Adverts / music vids with very big lighting budgets and I never noticed the pros using any of these tricks though.

as the previous posters say - the key seems to be clean, even lighting on your greenscreen and putting your talent as far away as you can from the screen.