Hello,
I'm attempting to merge a number of DEMs in .flt format using gdal_merge.py.
It's NED 1/3 arc second data, so each one is a Float32 10812x10812 raster with
a range of values from a few meters below sea level to 1.4km. I'm getting back
an image with an incorrect datatype even though I believe that I'm using the
right "-ot Float32" parameter to gdal_merge.py. I appear to have gdal 1.5.4 on
this machine; I can upgrade to a newer one if necessary but I'd first like to
make sure I'm not using the tool incorrectly.
Here's the command I use:
gdal_merge.py -o 38122.tif -of GTiff -ot Float32 -v -ul_lr -122.05
38.05 -121.95 37.95 10m/*.flt
What I get back is a 1080x1080 GeoTIFF with the correct bounds that I'm
expecting, but what appears to be garbage data or perhaps just raw floating
point values misinterpreted as bytes. Here's the output showing Byte values
instead of Float32 as I'd expect:
Band 1 Block=1080x7 Type=Byte, ColorInterp=Gray
Min=0.000 Max=255.000
Minimum=0.000, Maximum=255.000, Mean=108.657, StdDev=66.615
This is a sample of the resulting image in pseudocolor, showing the vertical
banding every 4px that makes me think the bytes are just a raw Float32 stream:
http://mike.teczno.com/img/38122-rainbow.png
Here is a sample input band:
Band 1 Block=10812x1 Type=Float32, ColorInterp=Undefined
Computed Min/Max=-8.170,1440.937
NoData Value=-9999
Am I using -ot incorrectly?
-mike.
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michal migurski- [email protected]
415.558.1610
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