Changes between Version 28 and Version 29 of NetCDF_exportUpdateChanges
- Timestamp:
- Oct 12, 2011, 10:38:21 PM (12 years ago)
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NetCDF_exportUpdateChanges
v28 v29 61 61 62 62 63 === Continue saving GDAL custom attribute tags by default to CRS definition, but add option not to save===63 === SRS Handling: Continue saving GDAL custom attribute tags by default to CRS definition, but add option enot to sav === 64 64 65 65 '''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: 72 72 * A "spatial_ref" tag containing full OGC WKT string, including datum and EPSG codes if known. 73 * A geotransform array saved as a string (GeoTransform), and individual corner coordinates (NN, SS, WE and WW). 73 * A geotransform array saved as a string (GeoTransform), 74 * and individual corner coordinates (NN, SS, WE and WW). 74 75 75 76 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. 78 79 80 **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? 81 82 {{{ 83 !comment 79 84 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. 85 }}} 80 86 81 87 '''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). 84 90 85 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.91 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. 86 92 87 93 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 .