[gdal-dev] how to acces to PDS meta data

[Frank Warmerdam]

Ludovic Mercier wrote:
> Hi all,
> 
> I try to use gdal and otb (http://smsc.cnes.fr/PLEIADES/lien3_vm.htm)
> with pds file.
> I try to get value associated to a key (meta-data).
> for an exemple the file : Index of /gdal/data/mc02.img contain :
> SPACECRAFT_NAME                = "MARS GLOBAL SURVEYOR"
> INSTRUMENT_NAME                = "MARS ORBITER CAMERA"
> INSTRUMENT_ID                  = "MOC-WA"
> TARGET_NAME                    = "MARS"
> FILTER_NAME                    = "RED"
> 
> I would like to access to the key/value FILTER_NAME. But the function
> GetMetadata return nothing !
> I look in the source code (file pdsdataset.cpp) and the interresting
> method is "GetKeyword()" but it is a private method.
> 
> Is someone have an idea how to get all meta data or specific meta-
> data ?
> 
> I think is it impossible in fact.. but perhaps is it possible if i add 
> new functionnality
> in the pds driver....

Ludovic,

You are correct that none of these header fields are currently exposed
by the PDS (or ISIS2, and ISIS3) drivers as metadata.  It would be
quite easy to modify the driver to transfer specific keywords and their
associated value to the metadata object, but it is unclear which ones would
be useful.

I have gone ahead and added support in the PDS driver to transfer a bunch
of keywords over.  The gdalinfo results now look like:

...
Origin = (-10668384.903788566589355,3852176.483988761901855)
Pixel Size = (926.115274429321289,-926.115274429321289)
Metadata:
   FILTER_NAME="RED"
   DATA_SET_ID="MGS-M-MOC-4-WAMOS-V1.0"
   PRODUCT_ID="MC02"
   PRODUCER_INSTITUTION_NAME="MALIN SPACE SCIENCE SYSTEMS"
   PRODUCT_TYPE="MOSAIC"
   MISSION_NAME="MARS GLOBAL SURVEYOR"
   SPACECRAFT_NAME="MARS GLOBAL SURVEYOR"
   INSTRUMENT_NAME="MARS ORBITER CAMERA"
   INSTRUMENT_ID="MOC-WA"
   TARGET_NAME="MARS"
   CENTER_FILTER_WAVELENGTH=600.0000
   BANDWIDTH=50.0000
   PRODUCT_CREATION_TIME=2001-11-28T00:00:00
   NOTE="GEODESY CAMPAIGN MOSAIC"
Corner Coordinates:
...

The new support is only in trunk and new keywords can be added quite
easily.

   http://trac.osgeo.org/gdal/changeset/16077

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent