[Gdal-dev] Projected vs Geographic Coordinate Systems

Frank Warmerdam warmerdam at pobox.com
Tue Mar 20 01:30:54 EDT 2007

Simon Perkins wrote:
> So, just to clarify, if OpenEV is displaying a vector layer, it displays 
> the coordinates isotropically? i.e. horizontal screen distances relate 
> to longitude in the same ratio as vertical screen pixels relate to 
> latitude?


 >  Is this pretty common practice in the GIS world?

Yes, nearly universal I think.

> I guess I've just been spoiled by playing with Google Earth too much... :)

To the best of my knowledge Google Earth has one display project
(some sort of Mercator) and it reprojects everything to that.  That
approach is fine too if you are willing to reproject everything - either
in advance or on the fly.  Many apps will allow you to do this too if you

Oddly, OpenEV can reproject rasters on the fly but not vectors.  But that
is just an unfortunate omission, not really a design decision.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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