Rui Lopes wrote:
the tz table is from your shapefile at http://efele.net/maps/tz/world/ ?
That's one, but Jesper has another one (and we are trying to reconcile our logical differences). Anything that matches a tzid with a geometry should be appropriate.
By map you mean the TZ map from your shapefile?
Yes, same as above.
Can you elaborate a bit about the buffering and intersection? (I'm starting to enter into the GIS world, so I don't yet known the lingo).
Buffering is "growing" a geometry by some fixed amount; think adding a ring around a polygon. So to test if a point is within a geometry, and to account for errors, you can try to test if a ring around the point intersects with the geometry. The size of the ring should be determined from the precision of the maps. Eric.