If the projector is hanging on the target line, that is the safest place in the room. About 7-8 feet from the screen is completely okay to avoid a ball bouncing off the screen and coming back to hit a projector, and no more than 3 or 4 feet behind the player to avoid shadows. Based on this, you can measure the distance to the impact screen and the height of the screen, and then calculate the throw ratio you need. A projector with throw ratios ranging from 0.5 to 1.1 helps you put the projector where it is needed to fill the screen, while being mounted safely outside the hitting area (and without casting a shadow).