Changes between Version 28 and Version 29 of NetCDF_exportUpdateChanges

Timestamp:

Oct 12, 2011, 10:38:21 PM (13 years ago)

Author:

pds

Comment:

--

NetCDF_exportUpdateChanges

@@ -61 +61 @@
 
 
-=== Continue saving GDAL custom attribute tags by default to CRS definition, but add option not to save ===
+=== SRS Handling: Continue saving GDAL custom attribute tags by default to CRS definition, but add option enot to sav ===
 
 '''Related fix''': N/A [[BR]]
@@ -71 +71 @@
 In addition to following the CF-1 conventions to save projection metadata, the NetCDF driver writes metadata in several custom attributes:
  * A "spatial_ref" tag containing full OGC WKT string, including datum and EPSG codes if known. 
- * A geotransform array saved as a string (GeoTransform), and individual corner coordinates (NN, SS, WE and WW).
+ * A geotransform array saved as a string (GeoTransform),
+ * and individual corner coordinates (NN, SS, WE and WW).
 
 The new WRITE_GDAL_TAGS driver creation option allows the user to choose not to write these tags. However it would be set to 'YES' by default.
@@ -77 +78 @@
 The new implementation saves the GeoTransform array only if the lon/lat or x/y values are not written to the file, and the corner coordinates are never saved as they are redundant.
 
+**PDS comment**: do you mean just "lon/lat" above? As that's what it looks like in the code. And the new driver always saves X/Y right?
+
+{{{
+!comment
 Note: when importing files in NetCDF format, the driver checks the GDAL-written WKT matches the projection information stored in the CF-compliant attributes. If there is a conflict, the CF-compliant CRS will be considered as authoritative.
+}}}
 
 '''Rationale''': 
@@ -83 +89 @@
 We assume by default that if users export to a NetCDF file from GDAL, then they may wish to import into GDAL again and retain full information. Currently, the CF-1 convention doesn't allow saving all the projection information that GDAL can manipulate via a WKT (such as named Datums, and EPSG authorities).
 
-However, there is certainly a use-case to export to a NetCDF file with no intention to access again via GDAL and use purely for use by CF-1 applications, in which case we don't need to save the added metadata.
+However, there is certainly a use-case to export to a NetCDF file with no intention to access again via GDAL and use purely for use by CF-1 applications, in which case the user may wish to have no additional metadata present.
 
 Note: In the longer-term we would view it as advantageous that the CF-1 conventions were augmented to allow recording of full datum information, and reduce the need to store extra CRS information in GDAL-managed attributes. However this will require agreement of the CF-1 community for a new standard, and would take time to agree upon and adopt.  See https://cf-pcmdi.llnl.gov/trac/ticket/69 .