'Location in global frame, with altitude relative to the home location
(a :py:class:`LocationGlobalRelative`).
The latitude and longitude are relative to the
`WGS84 coordinate system <http://en.wikipedia.org/wiki/World_Geodetic_System>`_.
The altitude is relative to :py:attr:`home location <Vehicle.home_location>`.
This is accessed through the :py:attr:`Vehicle.location` attribute:
.. code-block:: python
print "Global Location (relative altitude): %s" % vehicle.location.global_relative_frame
print "Altitude relative to home_location: %s" % vehicle.location.global_relative_frame.alt'

@property
def global_relative_frame(self):

    return LocationGlobalRelative(self._lat, self._lon, self._relative_alt)
