Marcos,
Ah, that makes a lot of sense. I was thinking that there were just
some default parameters being used for Albers and LCC, but clearly
that wouldn't make them very useful! So basically somebody sets some
parameters they like and then asks the EPSG for a number that
represents that parameter set?
I'm surprised there does not appear to be an EPSG number for the
"standard" Albers projection of the US (standard parallels of 29.5 and
45.5 North, and a central meridian of 96 West). If it is indeed
missing, could we request it and add it to the Motherlode TDS so that
it could be used to display all those CONUS model outputs from NCEP?
Thanks,
-Rich
On Wed, Oct 17, 2012 at 5:24 PM, Marcos Hermida
<mhermida@xxxxxxxxxxxxxxxx> wrote:
> 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
>>>
>>> _______________________________________________
>>> thredds mailing list
>>> thredds@xxxxxxxxxxxxxxxx
>>> For list information or to unsubscribe, visit:
>>> http://www.unidata.ucar.edu/mailing_lists/
>>
>>
>>
>
--
Dr. Richard P. Signell (508) 457-2229
USGS, 384 Woods Hole Rd.
Woods Hole, MA 02543-1598
