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I have four .HGT topography tiles (tile1,tile2,tile3,tile4 in the photo below). They are in geographic coordinate system. I would like to merge those four tiles, and then from that merged raster layer to cut off a piece (green rectangle in the photo) and to make a new raster layer from that cut off green rectangle piece.

The corners of the rectangle are suppose to be defined by adding 10 degrees of latitude and longitude to the central point (55,-2) of the green rectangle piece:

enter image description here

How can this be done in QGIS? How can four .HGT raster files be merged and then a new raster layer cut off from it?

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Load your files into Qgis. ( via add layer - raster ).

Merge your rasters with the raster function "Merge" (menue raster).

Use the function "Clipper" from the raster menue. Within Clipper you can set the extend to your bounding box coordinates.

  • Thank you @Matte. It is interesting that at the end of the Merging process I get the following two error messages: error1, error2 I am using QGIS 2.8.7. Wien. The merging succeeds though, and Clipping executes without any problem, but I am wondering if the upper two error messages are somehow making an incorrect or corrupted merged raster file? – marco Apr 14 '16 at 15:11
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    The second error is put out because of the first one. And the first one says something of memory read error. That could have been been quite many things. But it is not an error of reading the file but the memory addressing during the process. You can only check if the output looks fine. Otherwise you could re-run the process to be sure. It might not pop up the second time. – Matte Apr 15 '16 at 5:34
  • Thank you @Matte. I rerun the process and got the same error again on "Merge". The merged and clipped raster looks fine though, but its so large that I am afraid that there might be some sort of error in it, or corrupted cell-pixel, which I can not see with my bare eyes. Is there a way to check if the raster if corrupted or similar? – marco Apr 15 '16 at 15:03

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