Direction definition
Define a direction in metadata keys.
Overview
For the metadata keys which define a direction, com.apple.quicktime.direction.facing and com.apple.quicktime.direction.motion, directions are specified as a string consisting of one or two angles, separated by a slash if two occur. The first is a compass direction, expressed in degrees and decimal degrees, optionally preceded by the characters “+” or “-”, and optionally followed by the character “M”. The direction is determined as accurately as possible; the nominal due north (zero degrees) is defined as facing along a line of longitude of the location system, unless the angle is followed by the “M” character indicating a magnetic heading. The second is an elevation direction, expressed in degrees and decimal degrees between +90.0 and -90.0, with 0 being horizontal (level), +90.0 being straight up, and -90.0 being straight down (and for these two cases, the compass direction is irrelevant).