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I have 4 SRTM raster like this: enter image description here

I want to merge them into 1, but when I do this, something like this happens (I only tried it with two of them here):enter image description here

I also tried changing the min and max values that are here both 0 to the min and max values from the two used rasters but it doesn't change. Do you have any idea what's the problem here and what I can do?

Here's the Log file:

QGIS version: 3.8.0-Zanzibar QGIS code revision: 11aff65f10 Qt version: 5.11.2 GDAL version: 2.4.1 GEOS version: 3.7.2-CAPI-1.11.0 b55d2125 PROJ version: Rel. 5.2.0, September 15th, 2018 Processing algorithm… Algorithm 'Merge' starting… Input parameters: { 'DATA_TYPE' : 5, 'INPUT' : ['C:/Users/.../srtm/eu_dem_v11_E30N20/eu_dem_v11_E30N20.TIF','C:/Users/.../srtm/eu_dem_v11_E30N30/eu_dem_v11_E30N30.TIF'], 'NODATA_INPUT' : None, 'NODATA_OUTPUT' : None, 'OPTIONS' : '', 'OUTPUT' : 'TEMPORARY_OUTPUT', 'PCT' : False, 'SEPARATE' : False }

GDAL command: python3 -m gdal_merge -ot Float32 -of GTiff -o C:/Users/.../AppData/Local/Temp/processing_0bf9ee3ec2f548829744a6bd244c96a2/60f16fc4e2394ab496e96b39dd323a73/OUTPUT.tif --optfile C:/Users/.../AppData/Local/Temp/processing_0bf9ee3ec2f548829744a6bd244c96a2/1eb95beda25545199dda413988a6c112/mergeInputFiles.txt GDAL command output: 0Traceback (most recent call last):

File "C:\PROGRA~1\QGIS3~1.8\apps\Python37\lib\runpy.py", line 193, in _run_module_as_main

"main", mod_spec)

File "C:\PROGRA~1\QGIS3~1.8\apps\Python37\lib\runpy.py", line 85, in _run_code

exec(code, run_globals)

File "C:\PROGRA~1\QGIS3~1.8\bin\gdal_merge.py", line 611, in

sys.exit(main())

File "C:\PROGRA~1\QGIS3~1.8\bin\gdal_merge.py", line 596, in main

fi.copy_into(t_fh, band, band, nodata)

File "C:\PROGRA~1\QGIS3~1.8\bin\gdal_merge.py", line 343, in copy_into

nodata_arg)

File "C:\PROGRA~1\QGIS3~1.8\bin\gdal_merge.py", line 124, in raster_copy

m_band)

File "C:\PROGRA~1\QGIS3~1.8\bin\gdal_merge.py", line 186, in raster_copy_with_mask

to_write = Numeric.choose(mask_test, (data_src, data_dst))

File "C:\PROGRA~1\QGIS3~1.8\apps\Python37\lib\site-packages\numpy\core\fromnumeric.py", line 422, in choose

return _wrapfunc(a, 'choose', choices, out=out, mode=mode)

File "C:\PROGRA~1\QGIS3~1.8\apps\Python37\lib\site-packages\numpy\core\fromnumeric.py", line 56, in _wrapfunc

return getattr(obj, method)(*args, **kwds)

MemoryError

Execution completed in 941.61 seconds

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2
  • Have you had a look at the histogramm for the merged layer? Have you made sure you choose the correct layers to merge? Have you changed any presets in the mergedialogue?
    – Erik
    Commented Jul 12, 2019 at 11:23
  • I chose the correct layers and I didn't change anything in the merge dialogue
    – DGxA
    Commented Jul 12, 2019 at 11:34

1 Answer 1

Reset to default
4

The merge was not successful: towards the end of you log you can read:

MemoryError

I would assume (also looking at the shape of the output "map", and judging from the large amount of time it took) this could be due to a too large region setting. Therefore, I would try setting a smaller output region and checking the required output resolution.

I downloaded two SRTM files, and merged them to take a screenshot which you hopefully find useful as a reference/comparison.

Settings:

enter image description here

Output:

enter image description here

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