In university, were using a screen which is actually a load of glass beads or something... Then use cameras called p2 cameras that have blue LED's on the front, and they make the screen blue, and because of the way the glass beads reflect, there are no shadows what so ever!
You don't need something so expensive though. Just good lighting (though a lot of shadows can be taken out), and a large area to shoot.
I wouldn't personally shoot outside...