[FWTools] Gdal_merge on large (50Gb) file

[Frank Warmerdam]

Shaun Kolomeitz wrote:
> Dear FWtools list,
> 
> I am having problems getting a large merge fire-up using the gdal_merge command.
> 
> I have three IMG (HFA format) files in the same projection (lat/lon) each 22Gb, 20Gb and 6Gb that I am trying to merge into a single image.
> 
> I keep getting the following -
> 
> Q:\satimages>gdal_merge -o qldg.img -of HFA -v z54gclip.img z55gclip.img z56gclip.img
> 
> Filename: z54gclip.img
> File Size: 48826x154049x3
> Pixel Size: 0.000130 x -0.000130
> UL:(137.590396,-9.999789)   LR:(143.918997,-29.966909)
> Copy 0,0,48826,154049 to 0,0,48826,154049.
> Traceback (most recent call last):
>   File "C:\PROGRA~1\FWTOOL~1.0B2\bin\gdal_merge.py", line 488, in ?
>     fi.copy_into( t_fh, band, band, nodata )
>   File "C:\PROGRA~1\FWTOOL~1.0B2\bin\gdal_merge.py", line 297, in copy_into
>     nodata_arg )
>   File "C:\PROGRA~1\FWTOOL~1.0B2\bin\gdal_merge.py", line 130, in raster_copy
>     t_xsize, t_ysize, t_band.DataType )
>   File "C:\PROGRA~1\FWTOOL~1.0B2\pymod\gdal.py", line 845, in ReadRaster
>     buf_xsize, buf_ysize,buf_type)
> MemoryError
> 
> Any suggestions ?

Shaun,

gdal_merge operates by loading each input image into RAM before writing it
to the merged file.  My suggestion would be to run gdalwarp to build your
mosaic.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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