[gdal-dev] gdal_merge.py outputs bad geotiff?

[Andrew Brooks]

Hello

When I use gdal_merge.py to merge two files and write a geotiff
it creates a file which PhotoshopCS3 cannot read.  Yet the result
of passing that tiff through gdal_translate produces a different
tiff (of a completely different size) which *is* readable.

% gdal_merge.py -v -o merged1.tif -of gtiff tl10dtm/w001001.adf tl67dtm/w001001.adf

The Photoshop error is "Could not complete your request because of
a problem parsing the TIFF file"

% gdal_translate -of gtiff merged1.tif merged2.tif
Input file size is 1200, 1600
0...10...20...30...40...50...60...70...80...90...100 - done.

I don't understand the size of the first one given that there's
no compression:
% ls -l merged1.tif merged2.tif
       981186 merged1.tif
      3854344 merged2.tif

However the tiffinfo output and the gdalinfo output are identical
for both files (except for the TIFF directory offsets, see below.

Andrew


tiffinfo
TIFF Directory at offset 0xee622 (976418)
   Image Width: 1200 Image Length: 1600
   Bits/Sample: 16
   Sample Format: unsigned integer
   Compression Scheme: None
   Photometric Interpretation: min-is-black
   Samples/Pixel: 1
   Rows/Strip: 3
   Planar Configuration: single image plane
   Tag 33550: 50.000000,50.000000,0.000000
   Tag 33922: 0.000000,0.000000,0.000000,510000.000000,280000.000000,0.000000
   Tag 34735: 1,1,0,15,1024,0,1,1,1025,0,1,1,1026,34737,8,0,2048,0,1,4001,2049,34
737,49,8,2054,0,1,9102,3072,0,1,32767,3074,0,1,32767,3075,0,1,1,3076,0,1,9001,30
80,34736,1,1,3081,34736,1,0,3082,34736,1,3,3083,34736,1,4,3092,34736,1,2
   Tag 34736: 49.000000,-2.000000,0.999601,400000.000000,-100000.000000
   Tag 34737: unnamed|Unknown datum based upon the Airy 1830 ellipsoid|

gdalinfo
Driver: GTiff/GeoTIFF
Size is 1200, 1600
Coordinate System is:
PROJCS["unnamed",
     GEOGCS["Unknown datum based upon the Airy 1830 ellipsoid",
         DATUM["Not_specified_based_on_Airy_1830_ellipsoid",
             SPHEROID["Airy 1830",6377563.396,299.3249646000043,
                 AUTHORITY["EPSG","7001"]],
             AUTHORITY["EPSG","6001"]],
         PRIMEM["Greenwich",0],
         UNIT["degree",0.0174532925199433],
         AUTHORITY["EPSG","4001"]],
     PROJECTION["Transverse_Mercator"],
     PARAMETER["latitude_of_origin",49],
     PARAMETER["central_meridian",-2],
     PARAMETER["scale_factor",0.999601272],
     PARAMETER["false_easting",400000],
     PARAMETER["false_northing",-100000],
     UNIT["metre",1,
         AUTHORITY["EPSG","9001"]]]
Origin = (510000.000000000000000,280000.000000000000000)
Pixel Size = (50.000000000000000,-50.000000000000000)
Metadata:
   AREA_OR_POINT=Area
Image Structure Metadata:
   INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  510000.000,  280000.000) (  0d22'58.02"W, 52d24'23.61"N)
Lower Left  (  510000.000,  200000.000) (  0d24'30.74"W, 51d41'15.02"N)
Upper Right (  570000.000,  280000.000) (  0d29'54.91"E, 52d23'28.35"N)
Lower Right (  570000.000,  200000.000) (  0d27'31.76"E, 51d40'21.17"N)
Center      (  540000.000,  240000.000) (  0d 2'29.21"E, 52d 2'25.00"N)