Say you want to evaluate a piece of land for its solar potential. Maybe it's surrounded by buildings or trees. You can use a device called the Solar Pathfinder (see below). It essentially reflects the surrounding features to create a map of the sky—a hemispherical projection—corresponding to all the hours of the year.
I believe the Solar Pathfinder is a direct descendant of the Globoscope, an instrument created by Swedish architect Gunnar Pleijel in 1947. Pleijel described the Globoscope in 1963 as "a paraboloidal mirror with a vertical axis of revolution, which is photographed from above through a lens." The "little-known device" was resurrected by Penn State researchers in a 1977 paper in Solar Energy.