[gdal-dev] Merging tiff4 files

[Frank Warmerdam]

Andrea,

I think the problem is that these are one bit files with
a black/white color table and by default gdal_merge.py
does not copy the color table.  If you add the -pct
switch it should do so.

I imagine the result file does have pixels with values of
zero and one, but you won't see them as different in
most viewers.

Best regards,

On Fri, Sep 2, 2011 at 2:40 PM, Andrea Peri <aperi2007 at gmail.com> wrote:
> Hi,
> I need to merge some Tiff4 (bw) raster and obtain 1 only more big tiff4
> raster.
>
> I'm try-ing this with gdal_merge.py
> and using a comand like this:
>
> python gdal_merge.py -o ../raster/216.tif -n 1 -ot Byte
> ../raster/10k/216*.tif
>
> Unfortunately the resulted raster is intellegible (the input raster was all
> clearly visible).
> It is an all black image :(
>
> I tried also with option "-n 0" but the result is the same.
>
> I analyze the input raster using gdalinfo, and the result is this.
>
> ------------------
>>gdalinfo.exe ../raster/10k/216100.tif
> Driver: GTiff/GeoTIFF
> Files: ../raster/10k/216100.tif
>        ../raster/10k/216100.tfw
> Size is 10065, 10049
> Coordinate System is:
> LOCAL_CS["unnamed",
>     UNIT["unknown",1]]
> Origin = (1561222.860009765700000,4927094.449960937700000)
> Pixel Size = (0.500000000000000,-0.500000000000000)
> Metadata:
>   AREA_OR_POINT=Point
>   TIFFTAG_RESOLUTIONUNIT=1 (unitless)
>   TIFFTAG_SOFTWARE=Arc/Info
>   TIFFTAG_XRESOLUTION=2
>   TIFFTAG_YRESOLUTION=2
> Image Structure Metadata:
>   COMPRESSION=CCITTFAX4
>   INTERLEAVE=BAND
>   MINISWHITE=YES
> Corner Coordinates:
> Upper Left  ( 1561222.860, 4927094.450)
> Lower Left  ( 1561222.860, 4922069.950)
> Upper Right ( 1566255.360, 4927094.450)
> Lower Right ( 1566255.360, 4922069.950)
> Center      ( 1563739.110, 4924582.200)
> Band 1 Block=10065x32 Type=Byte, ColorInterp=Palette
>   Image Structure Metadata:
>     NBITS=1
>   Color Table (RGB with 2 entries)
>     0: 255,255,255,255
>     1: 0,0,0,255
> -----------------
>
> What am I wrong ?
>
> Thx,
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>
>
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>



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