[Xastir] Openstreetmap?

[Tapio Sokura]

Brad Douglas wrote:
> IMO, OSM is a useless kludge.
> 
> There are no specs for coordinate systems, datum, etc.  That means each
> data collector uploads data in the system they deem useful to them,
> which makes accuracy, by any stretch of the imagination, impossible.

OSM is all WGS-84 lat/lon, or at least it is supposed to be. This is 
mentioned here and there in the OSM wiki, but I guess it could be 
displayed more prominently. All location information in the map database 
is stored as 2d-points (WGS-84 coordinate pairs). Points can be 
connected to other points to form polylines and polygons, but this 
compound data is basically "projectionless" in the database. The 
assumption here is that the connected points are normally close enough 
together for there to be very little projection error in practice, at 
least away from the poles. Certainly the projection errors are in 
average smaller than the errors in the point data, most of which is 
collected using GPS tracklogs and/or aerial/satellite photographs.

Anyway OSM is not meant to be the final solution in mapping. First and 
foremost it's supposed to be a street/guide map, good enough to use for 
road/street navigation with or without a satellite navigation receiver. 
Over time it can become a useful general map as well, but it probably 
will never be a good topographic or accurately surveyed map. At least it 
is something that everyone can use under a CC compatible license. There 
aren't that many free (as in speech) street level maps to choose from 
in/of Europe. In many parts of Africa you are lucky if you can find 
street level maps at all.

   Tapio

PS. About OSM map use in Xastir, I can't see why you couldn't do that. 
Probably best would be to convert from OSM's own format to shapefiles 
and make them look pretty with dbfawk. There's a very basic utility 
called osm2shp to do some basic shapefile conversions. Of course the 
usefulness of OSM maps depends heavily on how fully mapped those areas 
you are interested in are.