[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[THREDDS #HKN-141488]: SRS status in THREDDS

Hi Steve,

As was announced in a recent TDS release, the TDS WMS service now includes 
EPSG:3857 in its list of supported SRS/CRS. This means that map images from WMS 
can be requested on this CRS.

The TDS still cannot read data in this CRS so it can't serve data stored in 
this CRS. Also, the TDS WCS service does not support reprojecting data so it 
cannot support this CRS as output.

Hope that helps,

Ethan

Ethan Davis wrote:
> Steve Baum wrote: 
> > A user wants to know about current SRS support in the THREDDS WCS/WMS 
> > services.
> > Specifically, he wants to known if SRS 900913 is supported.  Thank you.
> 
> I am not familiar with SRS 900913 but from a quick google search [2][3] it 
> looks
> like it is a pseudo Mercator projection that uses "spherical development" [4]
> and is used by some popular tools (google maps and such). At some point it was
> adopted as an EPSG CRS. At first as EPSG:3785 which has since been deprecated 
> in
> favor of EPSG:3857 "WGS 84 / Pseudo-Mercator".
> 
> It is not currently supported by the netCDF-java library which is used by the
> TDS to read data. This means you can't currently use the TDS to serve data 
> that
> is stored in this CRS.
> 
> It is, on the other hand, supported by GeoToolkit [1] which is used by the 
> ncWMS
> code to generate the WMS images. However, I have not seen it listed in any WMS
> GetCapabilities documents. I will check if and how the list of CRS supported 
> by
> the TDS WMS can be configured and get back to you.
> 
> > Steve Baum
> > Texas A&M Dept. of Oceanography
> 
> 
> Ethan
> 
> [1] http://jira.geotoolkit.org/browse/GEOTK-33
> 
> [2] 
> http://www.listware.net/201007/openlayers-users/66188-openlayers-users-sphericalmercator-and-srs-aliases-epsg900913-epsg3857-epsg3785-epsg102113.html
> 
> [3] http://osgeo-org.1803224.n2.nabble.com/EPSG-3785-td3781768.html#a3781768
> 
> [4] EPSG code table:
> 
> "Uses spherical development. Relative to an ellipsoidal development
> errors of up to 800 metres in position and 0.7% in scale may arise.
> Some applications call this WGS 84. It is not a recognised geodetic
> system: see WGS 84 / World Mercator (CRS code 3395)"


Ticket Details
===================
Ticket ID: HKN-141488
Department: Support THREDDS
Priority: Normal
Status: Closed