Changes between Version 16 and Version 17 of NetCDF_exportUpdateChanges


Ignore:
Timestamp:
Oct 5, 2011, 6:19:12 AM (13 years ago)
Author:
etourigny
Comment:

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  • NetCDF_exportUpdateChanges

    v16 v17  
    115115'''Related tix''': #2893 [[BR]]
    116116'''New -co options''':
    117   * WRITELONLAT=yes/no (default: yes for geographic, no for projected)
     117  * WRITELONLAT=yes/no/ifneeded (default: yes for geographic, ifneeded for projected)
    118118  * TYPELONLAT=float/double (default: double for geographic, float for projected)
    119119
    … …  
    125125
    126126Optionally using -co options listed above, also write 2D 'lat' and 'lon' arrays, which are specified as part of the CF-1 convention for map projections - but are not actually required for the Unidata-maintained NetCDF Java API and applications built upon them (eg ncWMS, Thredds Data Server).
     127
     128The ifneeded option of WRITELONLAT is used in the case of exporting a projection which is not supported by the CF-1.5 standard (e.g. sinusoidal), so any CF-1.5 compliant software can locate the points on a lon/lat map.
    127129
    128130'''Rationale''':
    … …  
    136138Thus we've chosen to make it ''optional'' to write these Variables, as they are redundant from GDAL's point of view (Lat and Lon are calculated on-the-fly), and they increase the size of a NetCDF file significantly. (E.g. if the actual band-data is stored as a 2D Byte array, but the lat and lon are stored as doubles, then the file-size can easily increase by 10X).
    137139
    138 === Changes to metadata items
     140=== Changes to metadata items ===
    139141
    140142As is common with many programs which manipulate netcdf data, a new GDAL metadata item (with version number) is added.  Also, the netcdf history attribute will be updated, and the Conventions attribute will be set to CF-1.5 to reflect support or latest CF convention and its projections.