Hi,
Problem Summary: The calls to GDALRasterBand::RasterIO() in
vpd::SourceData::getInterpolatedValue() and
vpd::SourceData::readHeightField() returns no-data-values as 55537
instead of the correct -9999 for gtopo30 data.
VPB: revision 911
OSG: revision 8321
GDAL version 1.5.1
The following command line is used to create a simple globe (all DEM
files from gtopo30 are used):
./osgdemd -d in/gtopo30/E020N40.DEM [...snip...] -d
in/gtopo30/W180S60.DEM --bluemarble-east -t
in/bluemarble/land_shallow_topo_east.tif --bluemarble-west -t
in/bluemarble/land_shallow_topo_west.tif --geocentric --radius-equator
6378000 --radius-polar 6378000 -v 1.4 -l 6 -o out/simple_globe.ive -a
out/simple_globe.osga
gdalinfo reports that the no-data-value for the DEM files are -9999:
dhcp6(bin)% /usr/local/bin/gdalinfo -stats in/gtopo30/E020N40.DEM
[...snip...]
Min=-9999.000 Max=5825.000
Minimum=-9999.000, Maximum=5825.000, Mean=-2347.600, StdDev=4873.500
NoData Value=-9999
... however, in the globe created by the command line above, the sea
level is high above ground. After some debugging, I made the following
observations:
* SourceData.cpp - vpd::ValidValueOperator::ValidValueOperator() obtains
the correct no-data-value (-9990) though GDALRasterBand::GetNoDataValue()
* In vpd::SourceData::getInterpolatedValue() no-data-values are not
clamped to 0.0f (zero) because GDALRasterBand::RasterIO() returns
no-data-values as 55537.0f (the same happens in
vpd::SourceData::readHeightField())
I highly temporary work-around hack was to alter the initialization of
vpb::ValidValueOperator::maxValue in line 38 in SourceData.cpp from
maxValue(FLT_MAX) to maxValue(55000.0f). Hence, the faulty
no-data-values are clamped to zero.
I am totally new to OSG/VPB. Does anyone have an idea of how to make a
permanent fix for this problem? Is it just an incompatibility problem
with GDAL 1.5.1? or...
Any advice would be greatly appreciated.
Best regards,
John Larring
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