How to play AE across 3 projectors

Although the answers below seem great, I don't think they understood what you were trying to do.

i am on this same journey path as you and just hit the same questions 😂

it would be interesting to see what you did? Did you split it as 3 compositions? If so, how?

did you have to use other software like mad mapper? I worry that 3 projectors, all at different angles and distances, that my little character that walks around will jump or shrink in size as he crosses over into another projector.

You have given us very little to go on. I am assuming that the image you shared is one view of a fairly low poly model of a house created by some kind of software or website that creates 3D models from a bunch of overlapping still images. 

I am also guessing that you have some other video that you want to project on this 3D model so as you move the model around in AE's 3D space it will look like something is projected on the surface of the house.

The After Effects 3D world is NOT true 3D. You get flat planes you can arrange in 3D space using the Classic 3D rendering engine. You get shape layers and text layers you can extrude and all other layers that you can only bend in the X Z axis if you are using the C4D rendering engine.

In order to texturize a 3D model, you will have to either purchase a third-party plugin like Video Copilot's Element 3D or you will have to try and use Cinema 4D Lite that comes with After Effects. Neither of these solutions will allow you to add an image in front of an After Effects light and project it onto the surface of the model. The best you can hope for is to project an image onto a flat surface or a surface distorted by a 3rd party plugin like Forge Freeform.

If you wanted to simulate projection in Element 3D or in Cinema 4D lite you would simply texture the surfaces in those apps/effects. 

Please explain in detail what you are trying to do. Include screenshots of your project so far showing us what you are doing to the layers you are having problems with by selecting layers and pressing the 'u' key twice. We will probably need to see more than one screenshot. There are dozens of ways to fake a projection and I'm not going to waste my time and yours by guessing what you are trying to do or what resources you have to work with. Give us something to go in and maybe someone can help.

You may want to look at the 3D camera tracker effect. You could place a solid on each part of the house and then replace the solid with the videos. Might be helpful if I'm understanding your question correctly.

sorry for the typ-o, it should be "teaching" no treating.