Phil,
I am using GDAL 1.6.0-5 and GRASS 6.4.0RC3. I guess my question was
more whether it was possible to keep the data in complex format, with
two layers per channel for imaginary and real components. I'm having a
hard time getting the image to look and have the values of a "real"
radarsat-2 image... I don't understand how the data can be used in
integer format (-1,0,1).
Benjamin
On 18-Mar-09, at 4:06 PM, Philippe Vachon wrote:
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
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