Re: [thredds] Albers or LCC supported as a WMS projection on the TDS?

• To: thredds@xxxxxxxxxxxxxxxx
• Subject: Re: [thredds] Albers or LCC supported as a WMS projection on the TDS?
• From: Ethan Davis <edavis@xxxxxxxxxxxxxxxx>
• Date: Wed, 17 Oct 2012 09:55:50 -0600

Hi Rich,

Even if a CRS is not listed, both ncWMS and TDS WMS can handle requests
for any CRS supported by the underlying GeoToolkit library. The CRS
database in TDS 4.2 does not contain EPSG CRS 9822 or 9802. However,
they should both be available in TDS 4.3. So, if you are trying this on
a TDS 4.3, you can just give it a try.

As for the WMS GetCapabilities CRS list, it is currently not user
configurable. For TDS 4.3 it would simply be a matter of a minor code
change (adding the two EPSG numbers to a list) and then rebuilding. It
is a bit more work in TDS 4.2, but not much harder, along with adding
the EPSG number to a list, we would need a WKT for each of the new
projections. (The CRS WKT needs to be in a form the GeoToolkit can read.)

We've kept the list to a minimum because in earlier versions we listed
all available projections and the list got quite large.

Are you using TDS 4.3? Do you need these CRS to be in the list or is
being able to request them enough?

Cheers,

Ethan

On 10/17/2012 8:17 AM, Rich Signell wrote:
> TDS folks,
> 
> What would it take to get Albers or LCC supported as a projection on
> the TDS WMS?
> 
> According to the WMS getCapabilities (for example:
> http://motherlode.ucar.edu/thredds/wms/fmrc/NCEP/GFS/CONUS_191km/NCEP-GFS-CONUS_191km_best.ncd?service=WMS&version=1.3.0&request=GetCapabilities
> 
> the supported projections are:
> <Title>Motherlode TDS</Title>
> <CRS>EPSG:4326</CRS>
> <CRS>CRS:84</CRS>
> <CRS>EPSG:41001</CRS>
> <CRS>EPSG:3857</CRS>
> <CRS>EPSG:27700</CRS>
> <CRS>EPSG:3408</CRS>
> <CRS>EPSG:3409</CRS>
> <CRS>EPSG:32661</CRS>
> <CRS>EPSG:32761</CRS>
> 
> Okay, so we don't see Albers Equal Area (EPSG:9822) or Lambert Conformal
> Conic 2SP (EPSG:9802) on the list.
> 
> But  TDS WMS is based on ncWMS, and on the ncWMS FAQ at:
> 
> http://www.resc.rdg.ac.uk/trac/ncWMS/wiki/FrequentlyAskedQuestions
> 
> it says that ncWMS "can produce images in any projection that is
> supported by the GeoTools library".
> 
> And it appears that GeoTools can support both Albers and LCC:
> 
> http://docs.geotools.org/latest/javadocs/org/geotools/referencing/operation/projection/package-summary.html
> 
> So would it be straightforward (or perhaps even easy) to allow the TDS
> WMS to support these?
> 
> Thanks,
> Rich
> 

-- 
Ethan Davis                                       UCAR Unidata Program
edavis@xxxxxxxxxxxxxxxx                    http://www.unidata.ucar.edu

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    • From: Rich Signell