[Gdal-dev] simple OGR/python projection question

[Frank Warmerdam]

On 10/4/05, John C Cartwright <John.C.Cartwright at noaa.gov> wrote:
> Hello All,
>
> I'm using the OGR python bindings to convert Plate
> Carree(Equirectangular) coordinates in meters to geographic coordinates
> in WGS84.  I'm getting an answer like:
>
> (-104.99999999546829, 38.999751150159064, 8426.3269814412379)
>
> I understand that the first two values are longitude and latitude, but I
> don't understand the third term. Can some one explain?

John,

The problem is that internally PROJ.4 only supports plate caree as a
spherical coordinate system, not ellipsoidal. So the large Z value (8.4km)
is the Z difference between the sphere and ellipsoid at the indicated
location.

Best regards,
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