On Mon, 24 Aug 2009, Frank Warmerdam wrote:
Roger Bivand wrote:
(reverting to list)
Correction, the user reported that:
Apparently, gdalinfo retrieves the correct min, max, and statistics,
despite the use of GDT_Int16.
on his Windows platform. The different GDAL versions ought to explain why
his gdalinfo says Int16 but gives statistics from UInt16.
...
On the trunk, GDT_Int16 is used too, so how does gdalinfo detect that it is
actually UInt16?
Roger,
I believe the min/max is actually being read from the file header in trunk
and is handled without regard to the actual imagery or it's type.
I skimmed the changelog for this driver and I didn't notice any obvious
changes in metadata / statistics handling so I'm surprised at this result.
Best regards,
Frank,
Having at last got the data and a current 1.7.0dev, I have to report that
on x86 Linux, I cannot reproduce the reading of Int16 as UInt16 reported
by the original questioner - I get Int16 and a negative minimum with
gdalinfo, and in rgdal using the same *.so. How the difference arose is
unclear, I can download FWTools and check on Windows.
I would argue for replacing Int16 by UInt16 in the LAN/GIS driver based on
PCI and ESRI references to the data types as unsigned, but am open to
other arguments.
Best wishes,
Roger
--
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: [email protected]
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