I literally read all the post associated with Keylight's noise issue; by the way, Dave LaRonde, you have the patience of a saint to repeatedly answer the same question!
So I now have many strategies to cope with the problem. My question is, where is the problem coming from? Is it After Effects, Keylight, the HVX camera, the DVCPro codec or a combination? As our budget increases I'd like to pursue solutions that will eliminate the problem, not just work around it. Thanks all (especially Dave).
Re: So just what IS the cause of Keylight noise by Dave LaRonde on Feb 25, 2008 at 4:06:06 pm
I find that that two things give me fits with keylight: an irregularly-lit backdrop and a backdrop that's too brightly illuminated. If you combine irregular illumination and over illumination, it's a killer.
In the studio, I've had excellent results by hooking the station engineers' portable vectorscope and waveform monitor to the camera and lighting the green (or blue) screen to 40-45 IRE units, and then lighting the subject separately so that highlights are at 100 units. The waveform monitor is a godsend: you easily can see hot and dark spots. When it's right, you see a thin, horizontal line between 40 & 45 IRE. The thinness of the line indicates even illumination from top to bottom, and a level line indicates even illumination from right to left.
Don't have a waveform monitor? Get a light meter! Move it around the backdrop! Measure the incident light readings on subject and background to get the proper ratio.
Getting at least 12 feet separation from the background really helps to cut down spill. So if you think you have a big green (or Blue) screen, you need a bigger one.
And outside, high overcast is great. If you use Mr. Sun as a key light on the subject, you'll get even illumination on the backdrop, and reflectors on the subject take care of the rest.
That's how I do it for important stuff.
For quick 'n dirty chroma keys, I use that two-step Keylight trick to get an okay key and remove spill. Sometimes I'll use a layer with Keylight to get a clean key, then use it as a track matte for the bottom layer, to which I've applied AE's own spill suppressor.
