when we discussed the issue of ellipsoid-support in netcdf-java back in March in the mailing-list it went very fast to: use one or another GeoAPI.
This sounded to me like a lot of work for you. If you don't plan to do this work in the near future (i.e. 2010), could you please send me the proj4j source. Maybe I can try then to add ellipsoid support of Stereographic and Transverse Mercator to netcdf-java (4.2) during summer.
The proj4 code is from the jhlabs partial port at
The ones that ive already done are at
On 2010-03-24 17:46, John Caron wrote:
Heiko Klein wrote:
I just found some time to look at the source of netcdf-java 4.1. As far as I can see, only some projections (LambertConformalConicEllipse, AlbersEqualAreaEllipse, UTM) support ellipsoids, while the others use a constant spherical earth with EARTH_RADIUS = 6371.229km
In particular, Stereographic projection doesn't support ellipsoids, so this explains the offset in my maps.
Would be nice to have this assured by one of the unidata-developpers. I mainly checked the ucar/unidata/geoloc/projection sources.
Yes, correct. We are slowly adding ellipsoid support, but only after we have a sample dataset that uses them. We are porting code from proj4, its rather time-consuming to get it right. if you have sample data where the ellipsoidal earth matters, send it along, we'll get to it when we can. or, if you have resources and expertise to port the proj4j code, i could send that to you and get you started.
On 2010-03-10 14:38, Jonathan Blower wrote:
This is a good question. ncWMS relies on netcdf-java for converting coords to wgs84 lat lon, so I'm copying this to the mailing list in the hope that someone can enlighten me about ellipsoid support in the library.
-----Original Message----- From: Heiko Klein<address@hidden> Sent: 09 March 2010 08:54 To: Jonathan Blower<address@hidden> Subject: ncWMS and ellipsoid-support in CF-1.2
I currently try to visualize some satellite ice-maps over the north-pole with ncWMS, but the data seems to be displaced by some 10-30km compared with the land-maps (generated by mapserver).
While geo-tools and therefore ncWMS support lots of coordinate reference systems for the presented maps, the support for ellipsoids was only added to CF-1.2. Do you know if ncWMS already supports the CF-1.2 features like semi_major_axis/semi_minor_axis for input-files, or does it assume the CF-1.0 spherical earth with 6371km radius?
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