  This paper explores different ways to render world-wide geographic maps in
virtual reality (VR). We compare: (a) a 3D exocentric globe, where the user's
viewpoint is outside the globe; (b) a flat map (rendered to a plane in VR); (c)
an egocentric 3D globe, with the viewpoint inside the globe; and (d) a curved
map, created by projecting the map onto a section of a sphere which curves
around the user. In all four visualisations the geographic centre can be
smoothly adjusted with a standard handheld VR controller and the user, through
a head-tracked headset, can physically move around the visualisation. For
distance comparison, exocentric globe is more accurate than egocentric globe
and flat map. For area comparison, more time is required with exocentric and
egocentric globes than with flat and curved maps. For direction estimation, the
exocentric globe is more accurate and faster than the other visual
presentations. Our study participants had a weak preference for the exocentric
globe. Generally, the curved map had benefits over the flat map. In almost all
cases the egocentric globe was found to be the least effective visualisation.
Overall, our results provide support for the use of exocentric globes for
geographic visualisation in mixed-reality.
