|Version 6 (modified by peifer, 19 months ago)|
Status of NetCDF CF-1.5 projection handling capability in work-in-progress NetCDF driver upgrade
The list of supported CF-1.5 projections is shown at http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.5/apf.html .
The table below shows tested ability to export projections from a GDAL raster - originally in GeoTIFF - to NetCDF CF-1.5 in each supported projection.
Hopefully the shorthand projection names listed below are fairly self-explanatory - they've been listed in the same order as that shown on the CF-1.5 appendix page.
Note: the current import capability has been tested to be the inverse of the export capability. If and when we are able to test capability to import NetCDF variants that don't have a direct CF-1 equivalent, we should add a supplementary table.
|Projection||Export- CF compliance||Export - openable by NetCDF Java||Updated||Note|
|AEA||Yes||Yes||18/10/11||Tested regular 2SP version - see AEA note below.|
|AzEq||Yes||No||18/10/11||See (1) below|
|LC-2SP||Yes||Yes||18/10/11||Tested 2SP version - CF-1 claims to have a 1SP version, but params quite different to OGC WKT so not tested. See note below.|
|LCEA||Yes||No||18/10/11||Tested regular OGC WKT with 1 std parallel version (CF-1 has alternative, see notes below). See (1) below re NetCDF-Java loading.|
|M-1SP||Yes||No||18/10/11||See (1) below|
|M-2SP||Yes||Yes*||18/10/11||Parameters appear correct, loads in NetCDF Java and IDV, but appears translated slightly (a few arc-minutes) from expected position|
|Polar St||Yes*||No*||18/10/11||See projection comments below re parameters. File opens in IDV, but then|
|Rot Pole||No||No||18/10/11||See projection comments below|
(1) For projections that won't load correctly as referenced grids in NetCDF Java, we've contacted the developers to ask for clarification/testing support. In most cases, the CF-1 attributes seem appropriate.
Issues with CF-1 implementation of specific projections:
- AEA (Albers Equal Area): The OGC WKT version has 2 Std parallels - whereas the CF-1.5 version says it can have either 1 or 2 std parallels. How would the 2SP version be converted to a CF 1SP version, and vice-versa?
- LCC (Lambert Conformal Conic): The OGC WKT 'Lambert_Conformal_Conic_2SP' maps clearly to LC in CF-1 with 2 std parallels. The CF-1 spec claims that a 1SP version can be used, but it doesn't include a 'scale_factor' as does the OGC WKT 'Lambert_Conformal_Conic_1SP'. Is there a way to do this conversion?
- LCEA (Lambert Cylindrical Equal Area): The CF-1 conventions claim this can be encoded with a 'scale_factor_at_projection_origin' alternative to standard parallel - how would this conversion be done back from OGC WKT?
- Polar St (Polar Stereographic): This projection's parameters in CF-1 are quite unusual, and significantly different from http://www.remotesensing.org/geotiff/proj_list/polar_stereographic.html. In particular finding a CF-1 equivalent for 'latitude of natural origin' is proving difficult.
- Rot pole (Rotated Pole): Not able yet to test: as seems GDAL needs support of advanced proj4 strings that can handle rotated coord systems.
(18.7 KB) - added by pds
19 months ago.
NetCDF version of original UTM-encoded small LANDSAT subset raster
(59.1 KB) - added by pds
19 months ago.
Tarball containing input exported to NetCDF in different projections
(43.2 KB) - added by etourigny
16 months ago.
horizontal datum parameters for use as reference for CF-1.7
- ellipsoid.csv (13.5 KB) - added by etourigny 16 months ago.
- prime_meridian.csv (1.6 KB) - added by etourigny 16 months ago.