[geotk] Netcdf Coverage
martin.desruisseaux at geomatys.fr
Tue Feb 1 10:42:57 EST 2011
Le 01/02/11 16:03, Fabien Carrion a écrit :
> In the metadata tab, selecting "Albedo", then the image description /
> dimensions / dimensions I don't have "Min value" or "Max value".
> Albedo is a percentage. I was waiting min value = 0 and max value = 100.
This may explain why the image is gray. Actually it is gray scale, but if
"minValue" and "maxValue" are not provided the gray scale range in an arbitrary
large scale (I don't remember which one exactly).
It may be worth to take a look again in the metadata tab, but by selecting
"NetCDF - Albedo" instead than "Geospatial - Albedo" in the combo box. You
should see the same metadata, but displayed as provided in the NetCDF file
(without the ISO 19115-like rearangement performed by "Geospatial"). If you
still don't see anything like min and max value, you may look rum "ncdump -h
<yourfile>" one the command line to be really sure.
If min and max values are not provided, in current Geotk implementation you have
the following choices:
* If you have some control on the way the NetCDF file were generated, you
may add the min and max attributes.
* Otherwise you may try to create a subclass of NetcdfImageReader and
override the "createImageMetadata" method in order to inject whatever
"min" and "max" attribute you wish in the IIOMetadata object. Let me know
if you choose this approach, so I can give some tips.
* A more heavy approach (but may also be more powerful) could be to use the
coverage-sql module, i.e. store the raster metadata (only the metadata,
not the data values) in a PostgreSQL database. This provides better search
capabilities in a large set of images, and give you more control on this
kind of metadata. Let my know if you prefer this approach.
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