I'm developing a Mapping Service with Bing Maps AJAX API and SQL Server 2008. The question which appears to me is should I use the geography or geometry data type. I researched a lot but doesn't found a satisfactory answer. Here are some links about the topic:
- SQL 2008 geography & geometry - which to use?
- http://www.mssqltips.com/tip.asp?tip=1847
- https://alastaira.wordpress.com/2011/01/23/the-google-maps-bing-maps-spherical-mercator-projection/
If I compare the two types I see the following points.
pro geography
- consistent distance calculation around the world (time line!)
- the coordinate system of the database is the same as the one which is used to add data to a map with the Bing Maps API (WGS84)
- precise
contra geography
- high computational costs
- data size constrained to one hemisphere
- missing functions (STConvexHull(), STRelate(),...)
pro geometry
- faster computation
- unconstrained data size
contra geography
- distance units in degree (if we use WGS84 coordinates)
The problem for me is that I don't need a fast framework, a great coverage (the whole world) and high functionality. So I would prefer the geometry type. The problem with the geometry type is, that I have to transform my data into a flat projection (Bing Map use SRID=3875), so that I get meters for the calculation. But when I use the Bing Maps projection (3875) in the database I have to transform my data back to WGS84 if I won't to display it in the map.