Represents direction in the coordinate reference system. In a 2D coordinate reference
system, this can be accomplished using a "angle measured from true north" or a 2D vector
point in that direction. In a 3D coordinate reference system, two angles or any 3D vector
is possible. If both a set of angles and a vector are given, then they shall be consistent
with one another.
Returns the azimuth and (optionnaly) the altitude.
In this variant of bearing usually used for 2D coordinate systems, the first angle (azimuth)
is measured from the first coordinate axis (usually north) in a counterclockwise fashion
parallel to the reference surface tangent plane. If two angles are given, the second angle
(altitude) usually represents the angle above (for positive angles) or below (for negative
angles) a local plane parallel to the tangent plane of the reference surface.
An array of length 0, 1 or 2 containing the azimuth and altitude angles.