So basically I design the animation to fit the screen I build, but how do I keep it from projecting outside of the screen? Are there special lenses or do I put some kind of stencil in front of the lense to keep it from lighting outside of the screen? Would it not blur through just a stencil (or whatever the correct word would be)?
Can a digital projector not project light in some areas and project it in others based on the source material? If not it would take some addition to the equipment side I would guess.
You're on the right track...
They are rear-projected screens. I'll have to take a look at the setup the next time I go, but as I recall, the screens are angled downward at you, which means the actual projector is probably somewhere up in the rafters near the ceiling above and behind the suspended screens.
Chances are, the projection is "shuttered" so that the light coming out of the lens is only the shape of the screen it's aimed at, and nothing around it. (Otherwise, you'd have blank space around the edges that aren't exactly "black" but rather a little bit of light).
Not 100% sure how Disney accomplished it, and I haven't worked much with video projectors, but it's probably a metal pattern installed *inside* the projector (as opposed to in front of the reflector). It's the same way theater stage lights (which I *do* have experience with) project patterns. A metal "gobo" (basically a thin sheet of metal with the pattern cut out of it) is placed between the bulb and the lens assembly. It blocks out all the light except the pattern that you want. (One thing to remember is that because of the optics of the lenses, the pattern needs to be installed upside down. The lenses will then flip the image rightside up.) You were right that a pattern between the projector and the screen wouldn't do anything (at least not as sharp-edged as what you're looking for).
If your video projector's lens assembly can be totally removed, you could probably install a cutout inside. But if you do this, you need to a) make sure that the material can stand the heat of the lamp, b) that you don't block TOO much of the opening, because the blocked light gets reflected back and dissipated as heat, and c) that this increase in temperature won't harm the projector.
Also, this will most likely void any warranty on the projector, so it's "proceed at your own risk".
-Rob
