Heiko Klein wrote:
Hi Jon,
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.
Best regards,
Heiko
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.
John
On 2010-03-10 14:38, Jonathan Blower wrote:
Hi Heiko,
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.
Cheers, Jon
-----Original Message-----
From: Heiko Klein <Heiko.Klein@xxxxxx>
Sent: 09 March 2010 08:54
To: Jonathan Blower <j.d.blower@xxxxxxxxxxxxx>
Subject: ncWMS and ellipsoid-support in CF-1.2
Hi Jon,
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?
Best regards,
Heiko
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