[gdal-dev] gdal2tiles.py generating dark tiles

[Allan Oware]

After digging around and comparing other images, I realised that the .IMG
lacks color interpretation since the ColorInterp parameter in gdalinfo
output is undefined
for the 3 bands.
When I attempt to gdal_translate to Gtiff with -expand rgb option, the
error output was: band 1 has no color table.
Any hint on how to properly define color interpretation for a .IMG ? I have
qgis, grass and gdal in an ubuntu setup.

Thanks,
Allan.



On Mon, Jul 14, 2014 at 10:02 AM, Allan Oware <allanoware at gmail.com> wrote:

>
> Hi all,
> Dark tiles are generated when I run gdal2tiles.py on a .IMG file(a scanned
> and georeferenced topographical map).
> A sample png of the tiles generated is found here
> <https://sites.google.com/site/lumtegis/files/519.png>. Even when i
> translate to tiff, the output is still the same. Why does
> gdal2tiles.py give this result ?
> The gdalinfo output is as below:
>
> Driver: HFA/Erdas Imagine Images (.img)
> Files: ALOI.IMG
>        ALOI.IMG.aux.xml
> Size is 3830, 2552
> Coordinate System is:
> GEOGCS["GCS_WGS_1984",
>     DATUM["WGS_1984",
>         SPHEROID["WGS_1984",6378137.0,298.257223563]],
>     PRIMEM["Greenwich",0.0],
>     UNIT["Degree",0.017453292519943295]]
> Origin = (32.999437318839924,3.000470692247897)
> Pixel Size = (0.000392066994127,-0.000392066994127)
> Metadata:
>   DataType=Generic
> Corner Coordinates:
> Upper Left  (  32.9994373,   3.0004707) ( 32d59'57.97"E,  3d 0'1.69"N)
> Lower Left  (  32.9994373,   1.9999157) ( 32d59'57.97"E,  1d59'59.70"N)
> Upper Right (  34.5010539,   3.0004707) ( 34d30'3.79"E,  3d 0'1.69"N)
> Lower Right (  34.5010539,   1.9999157) ( 34d30'3.79"E,  1d59'59.70"N)
> Center      (  33.7502456,   2.5001932) ( 33d45'0.88"E,  2d30'0.70"N)
> Band 1 Block=64x64 Type=UInt16, ColorInterp=Undefined
>   Description = Layer_1
>   Min=0.000 Max=255.000
>   Minimum=0.000, Maximum=255.000, Mean=225.572, StdDev=31.338
>   NoData Value=256
>   Overviews: 1915x1276, 958x638, 479x319, 240x160
>   Metadata:
>     STATISTICS_COVARIANCES=982.046346716112,845.521289084631,710.510646703791
>     STATISTICS_MINIMUM=0
>     STATISTICS_MAXIMUM=255
>     STATISTICS_MEAN=225.57242379015
>     STATISTICS_MEDIAN=0
>     STATISTICS_MODE=0
>     STATISTICS_STDDEV=31.337618714831
>     STATISTICS_SKIPFACTORX=1
>     STATISTICS_SKIPFACTORY=1
>     STATISTICS_EXCLUDEDVALUES=
>     LAYER_TYPE=athematic
>   Image Structure Metadata:
>     COMPRESSION=RLE
> Band 2 Block=64x64 Type=UInt16, ColorInterp=Undefined
>   Description = Layer_2
>   Min=4.000 Max=255.000
>   Minimum=4.000, Maximum=255.000, Mean=226.079, StdDev=29.739
>   NoData Value=256
>   Overviews: 1915x1276, 958x638, 479x319, 240x160
>   Metadata:
>     STATISTICS_COVARIANCES=845.521289084631,884.412989496947,765.062067015664
>     STATISTICS_MINIMUM=4
>     STATISTICS_MAXIMUM=255
>     STATISTICS_MEAN=226.07921779459
>     STATISTICS_MEDIAN=0
>     STATISTICS_MODE=0
>     STATISTICS_STDDEV=29.739081853631
>     STATISTICS_SKIPFACTORX=1
>     STATISTICS_SKIPFACTORY=1
>     STATISTICS_EXCLUDEDVALUES=
>     LAYER_TYPE=athematic
>   Image Structure Metadata:
>     COMPRESSION=RLE
> Band 3 Block=64x64 Type=UInt16, ColorInterp=Undefined
>   Description = Layer_3
>   Min=0.000 Max=255.000
>   Minimum=0.000, Maximum=255.000, Mean=172.929, StdDev=27.135
>   NoData Value=256
>   Overviews: 1915x1276, 958x638, 479x319, 240x160
>   Metadata:
>     STATISTICS_COVARIANCES=710.510646703791,765.062067015664,736.335138826829
>     STATISTICS_MINIMUM=0
>     STATISTICS_MAXIMUM=255
>     STATISTICS_MEAN=172.92884721066
>     STATISTICS_MEDIAN=0
>     STATISTICS_MODE=0
>     STATISTICS_STDDEV=27.135495920046
>     STATISTICS_SKIPFACTORX=1
>     STATISTICS_SKIPFACTORY=1
>     STATISTICS_EXCLUDEDVALUES=
>     LAYER_TYPE=athematic
>   Image Structure Metadata:
>     COMPRESSION=RLE
>
>
> Thanks,
> Allan.
> --
> Allan Oware
> Cell: +254 727 365820
>



-- 
Allan Oware
Cell: +254 727 365820
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