
50 Computing in Geographic Information Systems
For geo-coding of objects using the UTM system 16 digits are enough to
store the location to a precision of 1 meter, with one digit restricted to a binary
(northern or southern hemisphere), and the first digit of the zone restricted
to 0 to 6 (60 is the largest zone number).
This coordinate system has two real cartographic advantages. First, ge-
ometric computations can be performed on geographic data as if they were
located not on the surface of a sphere but on a plane. Over small distances, the
errors in doing so are minimal, although it should be noted that area compu-
tations over large regions are esp ...