Richard,

I can't really see a way to eliminate shadow problems without some kind of
bright lighting.  It would also be important for the chroma key effect to have
the background thoroughly illuminated to it appears as a solid color to the
equipment.

As for superimposing an image... you could run your camera signal into a
computer equipped with a video overlay board.  The software would superimpose
the video image over computer generated backgrounds   The software handles the
chroma key effect and could also help correct the shadow problems.  The SVGA
computer output is then passed into a scan converter and displayed on a
standard composite monitor or video projector with the images mixed.  Put a
touch-screen on the computer and your visitor interacts with the "video
console" to select locations, enter captions, select framing options, etc.
You didn't actually say what the exhibit was about, so I'm winging it here.

What type of equipment were you looking at to handle the chroma key effect?

Mark C. Vang
Freya Ventures
2100 Mediterranean Ave. Suite 15
Virginia Beach, VA 23451
(757) 340-0099

* Interactive touch screen computer exhibits for museums, science centers, and
aquariums. Technology solutions for museum exhibits. *