Need a Zero-Offset Projector (Home Theater) for a wall-shelf.?

Projector Wall Shelf

Your problem is unclear. If the shelf in mind is at the common 10 ft distance, and centered on the wall of projection, you should n't need to keystone adjust the image at all. If the shelf is not parallel to the floor, or at least, at a proper 90 degrees to the projection wall, level the shelf. If the shelf is too low or high you might have to tilt the projectors' front up or down,to center the screen then keystone correct the image, but almost all modern projectors of the last ten years include keystone adjustment, most of them automatic keystone adjustment. If your setup is at some skew to the room, you need to do some work on the room and your mounting position. just how it works. Old joke : Man sees boy searching around under a street lamp, asks what are you looking for? Boy says dropped my wallet across the street. Man says why are you looking for it here then? Boy says because the light is better here.