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I have downloaded ASTER DEM tiles(n=400), I have to merge/mosaic them. While doing so I got a problem with one tile which does not merge but displays correctly.

I have downloaded it again but still I get the same problem. How can I mosaic it with others. I have seen such a question on this forum but it has not been answered. Link. The only properties it has different with others is that its uncompressed size is 0 bytes, no columns nor resolution. I have realized that the bad tile, one is able to view the attribute table while the rest one can not. The tile number is ASTGTM2_N30E041_dem.tif Image

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Peter M Macharia
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    GDAL and QGIS do not have any problems with this image. – user30184 Jan 08 '16 at 15:57
  • @user30184 confirmed, shows as 3601x3601, 1 band INT16, nodata unspecified – Steven Kay Jan 08 '16 at 15:59
  • Does this mean its ArcMap that has a problem? – Peter M Macharia Jan 08 '16 at 16:13
  • How can I mosaic in QGIS? – Peter M Macharia Jan 08 '16 at 16:13
  • Integer overflowTraceback (most recent call last):File "C:\PROGRA~1\QGISPI~1\bin\gdal_merge.py", line 510, insys.exit(main())File "C:\PROGRA~1\QGISPI~1\bin\gdal_merge.py", line 496, in mainfi.copy_into( t_fh, band, band, nodata )File "C:\PROGRA~1\QGISPI~1\bin\gdal_merge.py", line 242, in copy_intonodata_arg )File "C:\PROGRA~1\QGISPI~1\bin\gdal_merge.py", line 75, in raster_copydata, t_xsize, t_ysize, t_band.DataType )File "C:\PROGRA~1\QGISPI~1\apps\Python27\lib\site-packages\osgeo\gdal.py", line 1051, in WriteRasterreturn _gdal.Band_WriteRaster(self, args, *kwargs)TypeError: not a string – Peter M Macharia Jan 09 '16 at 07:05
  • That is the error when I try to mosaic with QGIS – Peter M Macharia Jan 09 '16 at 07:05
  • I have realized that the bad tile, one is able to view the attribute table while the rest one can not – Peter M Macharia Jan 09 '16 at 07:26

2 Answers2

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This looks like an issue with ArcMap. I've been able to load this specific tile into QGIS, SAGA GIS and gvSIG without any problems (all of these use GDAL to open the raster)

QGIS does record the size correctly (3601 x 3601) and GDAL reports the pixel sizes...

Here's the gdalinfo output with metadata

$ gdalinfo ASTGTM2_N30E041_dem.tif 
Driver: GTiff/GeoTIFF
Files: ASTGTM2_N30E041_dem.tif
Size is 3601, 3601
Coordinate System is:
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"]]
Origin = (40.999861111111109,31.000138888888888)
Pixel Size = (0.000277777777778,-0.000277777777778)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_DATETIME=2011:03:15 19:52:13
  TIFFTAG_DOCUMENTNAME=created at
  TIFFTAG_IMAGEDESCRIPTION=SILC TIFF
  TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
  TIFFTAG_SOFTWARE=IDL 7.1.1, ITT Visual Information Solutions
  TIFFTAG_XRESOLUTION=100
  TIFFTAG_YRESOLUTION=100
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  40.9998611,  31.0001389) ( 40d59'59.50"E, 31d 0' 0.50"N)
Lower Left  (  40.9998611,  29.9998611) ( 40d59'59.50"E, 29d59'59.50"N)
Upper Right (  42.0001389,  31.0001389) ( 42d 0' 0.50"E, 31d 0' 0.50"N)
Lower Right (  42.0001389,  29.9998611) ( 42d 0' 0.50"E, 29d59'59.50"N)
Center      (  41.5000000,  30.5000000) ( 41d30' 0.00"E, 30d30' 0.00"N)
Band 1 Block=3601x1 Type=Int16, ColorInterp=Gray

This answer covers how to use a VRT to mosaic images and has some useful links. Arc allegedly supports this format, but I'm not in a position to check this. You could use Merge, but according to my calculations this would give a 70k x 70k raster.

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Steven Kay
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I have had exactly the same scenario with an ALOS (AW3D30) raster (tile N030E041). Using Mosaic to New Raster, this image was ignored. But using Mosaic, with the 'bad' image as the target worked fine.

Alan Stanton
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