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From "Martin Desruisseaux (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SIS-449) Extension to CF-conventions for bands in a netCDF variable
Date Sun, 17 Mar 2019 14:46:00 GMT
Martin Desruisseaux created SIS-449:
---------------------------------------

             Summary: Extension to CF-conventions for bands in a netCDF variable
                 Key: SIS-449
                 URL: https://issues.apache.org/jira/browse/SIS-449
             Project: Spatial Information Systems
          Issue Type: Improvement
          Components: Storage
            Reporter: Martin Desruisseaux
            Assignee: Martin Desruisseaux
             Fix For: 1.0


The _Global Change Observation Mission - Water (GCOM-W)_ files have content like below (simplified):

{noformat}
variables:
    short "Geophysical Data"(1976, 243, 2)
        float SCALE FACTOR = 0.01
        string UNIT = "C"
    float "Latitude of Observation Point"(1976, 243)
        string UNIT = "deg"
    float "Longitude of Observation Point"(1976, 243)
        string UNIT = "deg"
{noformat}

The "Geophysical data" variable is of size 1976 × 243 × 2, but the last dimension of size
2 is not defined anywhere in the file and does not correspond to any variable. We can build
a Coordinate Reference System (CRS) with latitude and longitude axes, but we can not include
in that CRS the third dimension since we don't know if it should be a depth, a time or other
kind of axis. That third dimensions could be interpreted as bands however.

We take the assumption that this dimension of size 2 means 2 bands. We support multi-banded
images for other formats (e.g. GeoTIFF), but multi-bands in a NetCDF file is more unusual
since a common practice is to use different variables instead (actually the netCDF format
does not have any explicit concept of band). This task is about upgrading the netCDF reader
for interpreting the dimensions that are not Coordinate Reference System dimensions as bands.




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