Re: [thredds] netCDF coordinate system (GeoGrid) criteria - requirements for THREDDS WMS

Hi Stephane:

comments are embedded

On 6/4/2010 1:17 PM, Stephane Poirier wrote:
Hi All,
THREDDS WMS requires NetCDF files to identify the coordinates system used. Checking this (for one of my NetCDF file) by opening in the Grid Panel of the ToolsUI application, I get the following http://www.oifii.org/do-org/dod/2010june01_netcdf41-tools_MRCC.4.2.0_amno_adj_alsi_ps_196012_r-nc.jpg

This is the right screen to look at (although i'd recommend starting to use the 4.2 ToolsUI). The dataType column shows "grid" when its succcessfully recognized as a "GeoGrid", which in this case it is not. Given that "coordTranforms" column in the middle table is blank, its likely not picking up the projection. Do you have the data variable pointing to it? The info button has some useful info. Also, try selecting "alsi" data variable in first table, then right click and do "try as Grid".

Send a dods URL if these pointers are insufficient.

http://www.unidata.ucar.edu/Projects/THREDDS/tech/tds4.0/reference/WMS.html page states, in order to comply to WMS requirements, a NetCDF files should have one or more variables shown as a GeoGrid. How can one tell a variable is shown as a GeoGrid? Alternatively, when I look at one of UCAR's NetCDF file (that seems to comply with the GeoGrid requirement), I get http://www.oifii.org/do-org/dod/2010june01_netcdf41-tools_ucar-station-profiler-wind_example.jpg. How can one tell a variable is shown as a GeoGrid?

This is definitely not a Grid, its point obs data. To simplify, a grid will have lat(lat), lon(lon), but a point data has lat(pt), lon(pt).

Regards,
Stephane
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Stephane Poirier, M.Sc. Optical Physics
Remote Sensing Application Software Developer
Geography Department, Burnside Hall
McGill University, Montreal, QC, Canada
http://geog.mcgill.ca
Stephane.Poirier2@xxxxxxxxx <mailto:Stephane.Poirier2@xxxxxxxxx>
Cell. (514) 994-3532
Fax: (514) 509-8833
--------------------------------------------------------------------
Stephane Poirier, M.Sc. Optical Physics
Remote Sensing Application Software Developer
3532 rue Sainte-Famille, Apt. 4
Montreal, QC, H2X 2L1, Canada
http://www.oifii.org
stephane.poirier@xxxxxxxxx <mailto:stephane.poirier@xxxxxxxxx>
Tel.: (514) 509-8833
Fax: (514) 509-8833
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