Actually this project is pretty specific to the Pi and its camera, though it can of course be modded for other hardware. "So it just happens that the horizonta

Actually this project is pretty specific to the Pi and its camera, though it can of course be modded for other hardware. "So it just happens that the horizontal distance covered by the Picamera’s image is roughly equal to the distance from the lens. If you are 10 feet from the lens, the image is about 10 feet across, 47 feet from the lens, about 47 feet across, and so on. Of course, other cameras may have a different field of view and won’t have this easy to determine correspondence."