Hi Rich,
to define either a Lambert Conformal Projection or Albers Equals Area
you need to provide a set of parameters (standards parallels, central
meridians, northing, easting...) so there are whole family of LCC and
Albers projections that you can use. Here you can see some well defined
ones, with their EPSG codes:
Albers:
http://spatialreference.org/ref/epsg/?search=Albers+Equal+Area&srtext=Search
LCC:
http://spatialreference.org/ref/epsg/?search=Lambert+Conic+Conformal+2SP&srtext=Search
If you want to use some of them all you have to do is add the OGC WKT to
the epsg database that is used by ncWMS/THREDDS. That database is the
epsg.properties file that lives in the epsg-wkt.jar and those are the
actual projections supported by the ncWMS/THREDDS.
So, for instance, if you want to add the Lambert Conic Conformal 2SP:
NAD83 / Massachusetts Island
(http://spatialreference.org/ref/epsg/2250/) you need to add to the
epsg.properties this OGC WKT:
http://spatialreference.org/ref/epsg/2250/ogcwkt/ with its EPSG code. It
would look like something like this:
2250=PROJCS["NAD83 / Massachusetts Island
(ftUS)",GEOGCS["NAD83",DATUM["North_American_Datum_1983",SPHEROID["GRS
1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6269"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4269"]],UNIT["US
survey
foot",0.3048006096012192,AUTHORITY["EPSG","9003"]],PROJECTION["Lambert_Conformal_Conic_2SP"],PARAMETER["standard_parallel_1",41.48333333333333],PARAMETER["standard_parallel_2",41.28333333333333],PARAMETER["latitude_of_origin",41],PARAMETER["central_meridian",-70.5],PARAMETER["false_easting",1640416.667],PARAMETER["false_northing",0],AUTHORITY["EPSG","2250"],AXIS["X",EAST],AXIS["Y",NORTH]]
Cheers!
On 10/17/2012 11:53 AM, Rich Signell wrote:
Ethan,
That's great that Albers, LCC and others should work with TDS 4.3 WMS.
That means it should work on:
http://motherlode.ucar.edu:9080/thredds
which is at TDS 4.3.15.
So on that server, I can get this WMS request to work using EPSG:4326:
http://motherlode.ucar.edu:9080/thredds/wms/grib/NCEP/NAM/CONUS_12km/files/NAM_CONUS_12km_20121017_1200.grib2?LAYERS=Temperature_height_above_ground&ELEVATION=2&TIME=2012-10-17T12%3A00%3A00.000Z&TRANSPARENT=true&STYLES=boxfill%2Frainbow&CRS=EPSG%3A4326&COLORSCALERANGE=263.7%2C302.6&NUMCOLORBANDS=20&LOGSCALE=false&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&FORMAT=image%2Fpng&SRS=EPSG%3A4326&BBOX=-128.16154395928,13.676912081443,-76.323087918557,65.515368122164&WIDTH=256&HEIGHT=256
But I can't get anything else to work.
Can you provide a modified version of the above request that works for
Albers (EPSG:9822) or LCC (EPSG:9802)
-Rich
On Wed, Oct 17, 2012 at 11:55 AM, Ethan Davis
<edavis@xxxxxxxxxxxxxxxx> wrote:
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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