[Gdal-dev] Projected vs Geographic Coordinate Systems

Simon Perkins sy at perkins.net
Tue Mar 20 00:06:50 EDT 2007

Simon Perkins wrote:
> I haven't looked at the source code for a long time, but what does 
> OpenEV do here? Do you convert geo-coordinates into some more 
> isotropic coordinate system before rendering, or do you just deal with 
> the funky anisotropy at all stages?

In a related question, if I have a vector layer in a geographic 
coordinate system, does OGR provide some convenient way to compute the 
relative scaling of degrees in the east-west and north-south directions? 
I guess it comes down to some simple geometry (the size of latitude 
degrees is uniform, the size of longitude degrees go like square of 
cosine of latitude, I think) , but just wondered if there was some more 
sophisticated procedure for what must be a common task.



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