gdalwarp assumes usage of WGS84 elipsoid when WGS84 datum is used.

[zekonja]

1. Add coordinate system information into tiff file

gdalwarp -t_srs "+proj=tmerc +lat_0=0 +lon_0=45 +k=1 +x_0=8500000 +y_0=0 +ellps=krass +datum=WGS84 +units=m +no_defs "  -of GTIFF -co TILED=YES -co COMPRESS=LZW -co
 TFW=YES -co PROFILE=GeoTIFF  11-38-125-1-2-2.tif  11-38-125-1-2-2_GT.tif

Output:

Creating output file that is 13086P x 11481L.
Processing input file 11-38-125-1-2-2.tif.
0...10...20...30...40...50...60...70...80...90...100 - done.
2. Get information about output file
gdalinfo  11-38-125-1-2-2_GT.tif
Driver: GTiff/GeoTIFF
Files: 11-38-125-1-2-2_GT.tif
       11-38-125-1-2-2_GT.tfw
Size is 13086, 11481
Coordinate System is:
PROJCS["unnamed",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",45],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",8500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]]]
Origin = (8431150.320000000298023,4503947.389999999664724)
Pixel Size = (0.407170801000005,-0.407170801000005)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  COMPRESSION=LZW
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  ( 8431150.320, 4503947.390) ( 44d11' 8.74"E, 40d40' 2.34"N)
Lower Left  ( 8431150.320, 4499272.662) ( 44d11'10.59"E, 40d37'30.81"N)
Upper Right ( 8436478.557, 4503947.390) ( 44d14'55.57"E, 40d40' 3.88"N)
Lower Right ( 8436478.557, 4499272.662) ( 44d14'57.27"E, 40d37'32.34"N)
Center      ( 8433814.439, 4501610.026) ( 44d13' 3.04"E, 40d38'47.36"N)
Band 1 Block=256x256 Type=Int16, ColorInterp=Gray

As it can be seen from output coordinate system isn't written properly. Insted of elipsoid Krasowsky elipsoid WGS84 is written. It seems that gdal assumes usage of WGS84 elipsoid when WGS84 datum is used.

Additional info:

gdalwarp --version

Output:

GDAL 1.8.0, released 2011/01/12

Tiff file is not attached since it has 147 MB. I believe you can reproduce it on any tiff file.

Please fix the bug.

[Even Rouault]

It is not a bug. Look at your -t_srs option : "+ellps=krass +datum=WGS84". The +datum will override the +ellps. And when you set a datum, it also imposes the ellipsoid used. You cannot ask for WGS84 datum and krass ellipsoid at the same time.