How to tweak global perspective when working with particles?

[Aurae5CBF]

I'm trying to create a semi-circular waterfall using particles. I have to duplicate multiple particle layers and arrange them in order to create an appearence of semi-circle (if you know better way please tell). There is a 360 still frame image used as a backdrop. My problem is that I don't know if it's possible to tell the AE where the horizon is and where the focal point is. The only way to achieve the illusion is by faking projection like in the screenshot. 

[P.M.B]

What particle system are you using?  Are those little yellow squares your particle layers?

[P.M.B]

Possibly a quick answer to how to control global perspective that may put you in the right direction is to create a camera.  With it you can have more control over perspective, focal point and you'll likely need to work from multiple perspectives using the default orthographic cameras (having two or more preview windows each with a different orthographic camera so you can easily align things in 3d space)

[Mylenium]

I concur with @Gutterfish - start by creating an actual camera layer and reference it inside the particle effects.

Mylenium