Most often we recommend using short-throw projectors 3000-3500 lumens, which from a distance of 1.5-2.5 meters create an image with a width of 3 to 5 meters and a height of 2 to 3 meters. Since the projector is relatively close, this minimizes possible shadows. Conventional (non-short-focus) projectors are 4 to 8 meters away to produce the same image.
In the second half of our video presentation we describe the technical conditions for projections, take a look: