The premise is that a turntable can function as a random access input device, anthropomorphic in scale and thus well suited for manipulation by hand.
Nikita Pashenkov: Optical Turntable as an Interface for Musical Performance (PDF - 83 pages)
^Any visual material can be played on the optical turntable. For instance cut outs of a topographical map.
See also: Projects: Spinalcat
Related: Dislocation: Cut-Up Cartography & Turntable sans vinyl
via Gizmodo