Hi Robert,
in their DEM_1m_VictoriaCrater.cub.vrt (which they didn't include
unfortunately) they have a "NoDataValue" field:
<NoDataValue>-3.40282265508890E+38</NoDataValue>
Even when I set that to say, -2000, and regenerate the
DEM_1m_VictoriaCrater.tif, osgdem/VPB always use a value of 0 for
everywhere there is a <NoDataValue> in the generated terrain and not the
value I set, -2000. Is it possible for osgdem/VPB to recognize the
<NoDataValue> feature instead of asking USGS to not use the
<NoDataValue> feature and put in a value of -2000 for everywhere they
don't have values as that would not be an nice solution.
Thanks Robert,
Linh
Robert Osfield wrote:
Hi Linh,
Thanks for the link to the data. I've downloaded and run osgdem on
the file specified but didn't get an error from GDAL/PROJ like you
did, so I'd guess that we have a different GDAL/PROJ versions. I
have:
GDAL 1.4.1.0, released 2007/04/09
When the database built I found that the crater itself built OK but
there was erroneous boarders to the data, looking like it osgdem/VPB
hasn't detected no data values.
Running the file through gdalinfo shows that GDAL itself isn't
detecting a no data value, and the range is rather wild:
gdalinfo DEM_1m_VictoriaCrater.tif -mm
Driver: GTiff/GeoTIFF
Size is 1278, 1694
Coordinate System is `'
Origin = (10343034.842341581359506,-120699.132580910620163)
Pixel Size = (1.011855074659235,-1.011855074660047)
Metadata:
AREA_OR_POINT=Area
TIFFTAG_SOFTWARE=IMAGINE TIFF Support
Copyright 1991 - 1999 by ERDAS, Inc. All Rights Reserved
@(#)$RCSfile: etif.c $ $Revision: 1.10.1.9.1.9.2.11 $ $Date:
2004/09/15 18:42:01EDT $
TIFFTAG_XRESOLUTION=1
TIFFTAG_YRESOLUTION=1
TIFFTAG_RESOLUTIONUNIT=1 (unitless)
Corner Coordinates:
Upper Left (10343034.842, -120699.133)
Lower Left (10343034.842, -122413.215)
Upper Right (10344327.993, -120699.133)
Lower Right (10344327.993, -122413.215)
Center (10343681.418, -121556.174)
Band 1 Block=64x64 Type=Float32, ColorInterp=Gray
Computed Min/Max=-340282265508890445205022487695511781376.000,-1373.288
Overviews: 320x424, 160x212, 80x106, 40x53
I don't know whether this is sign that GDAL itself needs updating to
handle this projection or whether the data itself is not set up well.
BTW what version of VPB/GDAL/OS are you using?
Robert.
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