[Gdal-dev] wrong nodata returned in GDAL dependent software

[Maciej Sieczka]

Hi,

Although my GeoTIFF has a value range 0-255 with nodata set to 256 [1],
both QGIS 0.8.1 and OpenEV output '255' when I query the area supposed
to be nodata. Any ideas what could be the culprit? I *suspect* the
issue might be in GDAL itself, as I can reproduce the problem in two
different viewers. Example GeoTiff attached. My specs:

GDAL 1.4.1 current SVN
OpenEV from FWTools 1.3.2
QGIS 0.8.1 current SVN

[1]
Driver: GTiff/GeoTIFF
Size is 54, 41
Coordinate System is:
PROJCS["NAD27 / UTM zone 13N",
    GEOGCS["NAD27",
        DATUM["North_American_Datum_1927",
            SPHEROID["Clarke 1866",6378206.4,294.9786982138982,
                AUTHORITY["EPSG","7008"]],
            AUTHORITY["EPSG","6267"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4267"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",-105],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","26713"]]
Origin = (586000.000000000000000,4931000.000000000000000)
Pixel Size = (500.000000000000000,-500.000000000000000)
Corner Coordinates:
Upper Left  (  586000.000, 4931000.000) (103d55'3.73"W, 44d31'44.94"N)
Lower Left  (  586000.000, 4910500.000) (103d55'15.97"W, 44d20'40.64"N)
Upper Right (  613000.000, 4931000.000) (103d34'40.81"W, 44d31'31.53"N)
Lower Right (  613000.000, 4910500.000) (103d34'56.89"W, 44d20'27.32"N)
Center      (  599500.000, 4920750.000) (103d44'59.34"W, 44d26'6.56"N)
Band 1 Block=54x41 Type=Byte, ColorInterp=Palette
    Computed Min/Max=0.000,255.000
  NoData Value=256

Maciek
-------------- next part --------------
A non-text attachment was scrubbed...
Name: test.tif.bz2
Type: application/x-bzip
Size: 6934 bytes
Desc: not available
Url : http://lists.osgeo.org/pipermail/gdal-dev/attachments/20070615/e34db1a7/test.tif.bin