Light

I am one who likes to think about things until I ether figure them out, or find something else to think about.
Anyway, lately I have been thinking about a idea I have had about projection things in 3d.
Now I know that this is not a original idea of mine, I have seen it in some Future - SIFI movies, but as of yet, it does not really exist.

So the way we project things right now is to take a LCD Projector and project something directly on a surface. This is a great concept, and we have done a lot with this.
But what if we could project Light on Light.

Is projecting light on light possible. I don't think so. Light does not have any physical characteristics. It can not inhabit a space. It can travel though space, but it also can travel through itself. For instance if you take a flash light and shine it, you will see a dot on a wall where the light hits. But if you keep that flash light shining on the wall, and take another flash light and shine it towards another wall causing the light paths to cross, you will still see the light spots on the walls. They will look just as clear as if we were not going thought light. Now I imagine that this is important because if it was not this way, we would have weird things showing up, or not showing up in the sky.
Light is important to us as it is because we can see things with it. Everything we see is created by light. If there was no light, there would be no color, there would be no heat, and there would be no food.

But if we could change the way light reacts to itself in order to form a 3d model of something wouldn't it be cool. Think of the possibilities, 3d movies, 3d plays, 3d interactive video games.....

Anyway, I don't have a answer to the way to make that work. I think that the only way to do it is to set up a lot of projectors from a bunch of different points then create a smoke machine that can be shaped to any object, or something like that. You can project on smoke. If not smoke, something else may be the answer, I don't know. But it is something to think about anyway.