I find the history of keying absolutely fascinating and I came across this article which talks about the developer who helped create the 3D keyer and the Master keyer, Daniel Pettigrew.
# Art of Keying
This article from Mike Seymour at FXguide talks about the evolution of digital keying. It was written in 2005 so is a little out of date but a fascinating read.
I have a thread called The Colourful History of Compositing but I’d be happy to join in a new thread talking specifically about the 3D keyer and the Master keyed