Orthophoto: Merging Tiffs in QGIS

Orthophoto: Merging Tiffs in QGIS

To merge several GeoTIffs into one file, QGIS may be used. See images of the process to the right.

  1. In the QGIS Browser Panel, select the GeoTiffs you want to merge and right click to add them to the main window.
  2. Select Raster > Miscellaneous > Merge
  3. In the Merge dialogue window, for Input files, browse to your directory containing your GeoTiff tiles. Select them all by holding Ctrl + select (Shift + select on a mac). For Output files, name your output file with the specified format of .tif for a georeferenced merged raster.
  4. Select “Creation Options” checkbox, and in the Profile drop down menu, select your compression level. We recommend any form of lossless compression (note: we do NOT recommend jpeg compression for GeoTiff merge export).

    “When we first merged two GeoTiffs of 5.24GB and 8.55GB without any compression, it generated a 24GB file! Use compression to save Hard Disk space.”

  5. Select OK, let it do its thing. Merging takes a long time (depends on the size of the project), be patient and trust the process. It took us 2.5 hours to complete the first merge on a late 2013 iMac.

 

We need a total of 2 files to drape Orthophoto on terrain in the GeoTIFF format.

  1. Image / Drone Scan / Satellite: Orthophoto
    .TIF or .TIFF *
  2.  Terrain model: DSM / DTM
    .TIF or .TIFF *

 

Remember:

  • All of these should be added in the same folder and zipped.
  • Include “DSM” in the name of the terrain model files – example: “Terrain_projectX_DSM.tif” and “Terrain_projectX_DSM.tfw” *).
  • When uploading, and prompted with “Do you want to split models” remember to select “No split”

 

* With a correctly created GeoTIFF, you will only have the .TIF file. However, if a .TFW file was automatically generated along with the .TIF file, you should include it in the folder along with all the other files to be zipped. The .TFW file contains spatial information.

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