[Marble-devel] Coordinate System of GeoPainter, GeoDataCoordinates and similar
marbledeveloper at gmail.com
Tue May 15 19:17:47 UTC 2012
I was wrong to respond in this thread yesterday. :)
I'm so sorry.
2012/5/15 Torsten Rahn <tackat at t-online.de>
> Hi Arne,
> On Montag, 14. Mai 2012 19:57:31 Arne Krüger wrote:
> > Hi,
> > I am fairly new to Marble and wondering which coordinate system is used
> > by classes such as GeoPainter and GeoDataCoordinates and how this
> > relates to different map projections. I probably will mostly use
> > OpenStreetMap which - as far as I know - uses a Mercator-On-Sphere
> > projection just like Google and Bing. However, since my application
> > requires drawing WG84 data onto the map I wonder whether I need to
> > transform my GPS coordinates before passing them to the Marble classes.
> Marble just assumes coordinate data with WGS 84 datum to be used. This is
> consistency with other data (such as OpenStreetMap) which is also provided
> with WGS 84.
> Apart from that there is no handling for other geodetic reference systems
> inside Marble.
> To visualize the data we provide support to display it on a Sphere
> on a Plate Carre projection (also named "Equirectangular" in the Marble
> Code and referenced as a "Flat Map" in the UI) and for Mercator.
> This kind of projection handling is done automatically by Marble's classes
> such as GeoPainter or the texture mapping classes that allow to map tiled
> bitmap data onto the globe.
> So if you create placemarks or if you paint using GeoPainter you don't
> have to
> worry about projections.
> For tiled bitmap data there are basically two source projections supported:
> "Mercator" (as used by OpenStreetMap and Google Maps) and
> "Equirectangular/Plate Carree" (as used by other maps such as Blue Marble).
> There is a short tutorial here that provides more information on how to
> integrate tiled bitmap data:
> > PS: I would highly appreciate a link to the API documentation on the
> > main project page, since the latter has a rather prominent google search
> > ranking, which the former is sadly lacking.
> Yes, we should at least reference it on the Marble Techbase Page.
> Best Regards,
> > Thanks for hints and clarifications.
> > Arne
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