[Gdal-dev] Problems with RS2 driver for import to grass

[Philippe Vachon]

Hi Ben,

I can't recall the exact details of how the GRASS r.in.gdal mechanism
works, but the results you describe are similar to importing calibrated
data into an integer raster. Calibrated SAR data is typically
represented as floats, as many of the values are in [0, 1), if I am not
mistaken. As such, the values when cast to integers will be clamped to 0
or 1 (or -1, in the case of the complex values).

I'm not certain about the GCP issue, since I can import all of the GCPs
in the Altona dataset using a little app I just whipped up. Perhaps it
could be something specific to GRASS that I'm not aware of. Happen to
know what version of GDAL you're using?

Cheers,
Phil

On Wed, Mar 18, 2009 at 12:48:01PM -0700, Benjamin Deschamps wrote:
> 
> I'm having a few issues importing RADARSAT-2 data to GRASS. I used:
> 
> r.in.gdal
> input=RADARSAT_2_CALIB:SIGMA0:/Users/Benjamin/Desktop/PK6621_DK406_FQ9_20080405_124900_HH_VV_HV_VH_SLC_(Altona_Promo)/product.xml 
> output=altona
> 
> to import the sigma nought calibrated data. For some reason this only
> imports 31 GCPs out of 350, and the values of the resulting GRASS layer are
> limited to -1, 0 and 1, so the map doesn't look like anything
> understandable. If I import uncalibrated values instead
> (RADARSAT_2_CALIB:UNCALIB:etc) I get a much more appropriate range of
> values, and all 350 GCPs are included.
> 
> How can I get all GCPs and a more appropriate range of values for the sigma
> nough subdataset? The dataset is available as part of the RADARSAT-2 demo
> dataset at 
> ftp://ftp.mda.ca/Fine%20Quad-Pol%20Dataset/Altona_%20R2_FineQuad9_HH_VV_HV_VH_SLC.zip
> ftp://ftp.mda.ca/Fine%20Quad-Pol%20Dataset/Altona_%20R2_FineQuad9_HH_VV_HV_VH_SLC.zip 
> 
> Thanks, Benjamin
> -- 
> View this message in context: http://n2.nabble.com/Problems-with-RS2-driver-for-import-to-grass-tp2499302p2499302.html
> Sent from the GDAL - Dev mailing list archive at Nabble.com.
> 
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