I work with WGS-84 coordinates and, most of the time, my map display (luciadmap) is in Mercator projection.
My client is surprised to see that, for a rectangular geometry:
- the line between the 2 upper points is not straight
- the line between the 2 lower points is not straight
N.B: Of course, the 2 upper points have the same latitude, and the 2 lower points have the same latitude.
My client expects to see only straight lines in Mercator. I think that is a wrong expectation. From my point of view, when a geographical zone is drawn on the map, it's sides should be linked by "great-circle" paths (arcs), not rhumb-lines.
Furthermore, all my geographical zones are stored in a Postgres+PostGis database. PostGis function are used to determine if some other geometries intersect with my zones. If I draw my zones using rhumb-lines and intersect using postGis, I fear that some geometries will appear completely outside of my zone. That would seem wrong!
Do you know how PostGis computes it's intersections? For you, how should geometrical zones be represented on a map?