I'm in the middle of updating a program that converts HDF-EOS files to netCDF. The old version is available here:
http://hdfeos.gsfc.nasa.gov/hdfeos/details.cfm?swID=84
It converts HDF-EOS5 files to netCDF, and attempts to preserve COARDS compliance (if the original file had COARDS-compatible metadata, so will the new one).
The updated version is going to handle both HDF-EOS2 and HDF-EOS5 (which already works), and I now want to make it CF-compatible. The auxiliary coordinate variables conventions in particular look like a good fit for the HDF-EOS Swath datatype, except for one thing.
Swaths let you map data variables to geolocation variables, but they also allow the geolocation dimensions to be different sizes than the data dimensions - the mapping between the dimensions contain offset and increment values so that, in the one-dimensional case:
Geoloc(i) is mapped to Data(i * increment + offset)
As near as I can tell from the CF spec, auxiliary coordinate variables must have the same size dimensions as their corresponding data variables, so there's no way to translate a Swath to CF-compliant netCDF without expanding and interpolating the gelocation variables to make them match the data dimensions. Does this make sense, or am I missing something?
- Bob
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Received on Tue Jul 27 2004 - 08:55:19 BST
