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Re: [netcdf-java] [CF-metadata] ESRI implementation of ellipsoidal-earth

  • To: Heiko Klein <Heiko.Klein@xxxxxx>
  • Subject: Re: [netcdf-java] [CF-metadata] ESRI implementation of ellipsoidal-earth
  • From: John Caron <caron@xxxxxxxxxxxxxxxx>
  • Date: Thu, 03 Feb 2011 10:30:01 -0700
On 2/3/2011 1:54 AM, Heiko Klein wrote:
I can confirm Davids observation. The European atmospheric models I'm working with use also unchanged WGS84 (geodetic) coordinates with a spherical earth.
The proj4 projection library (starting with 4.5, I think) tries to solve this in the following way (see http://osgeo-org.1803224.n2.nabble.com/How-to-convert-a-sphere-to-ellipsoid-with-correct-datum-td5486117.html ):
* if input and output projection both have a DATUM set (besides the ellipsoid) a geodetic/geocentric conversion is done. * if the datum is missing on any projection (input or output) no geodetic/geocentric conversion is made
As far as I've seen, the netcdf-java library 4.2 has no code for geodetic/geocentric conversion, so it follows the models. 

correct.
i guess whats missing is a method to convert lat/lon on one ellipsoid to lat/lon on another?
I don't even know if there is a way in newer CF-versions to set the Datum, besides the ellipsoid?
I think the only possible thing you can do currently is to set the ellipsoid parameters.
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