Tics Tics A tic is a registration or geographic control point for a coverage.
Tics are very important for registering map sheets during digitizing and editing.
Most geographic data is compiled and automated from a series of map sheets or aerial photographs. Maps are mounted on a digitizer or scanner one sheet at a time and digitized. Aerial photos are mounted in pairs in a stereoplotter. The next step is to transform the coordinates of all input sources into a single common coordinate system. Tics play an important role in map registration for these purposes.