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How do I reduce the size (or clip to a smaller area) a DEM raster in QGIS using existing tools?

I need smaller files for QGIS project transfer into QField.

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    youtube.com/watch?v=hPSIW1W3XjY for how to clip. Is it the geographical size of the raster or the size of the raster file that's causing problems? What format and compression are you using for the raster? Commented Jun 8, 2023 at 0:20
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    Compressing the raster will also make it significally smaller. For example see the COG examples here: docs.qfield.org/reference/data-format
    – Bera
    Commented Jun 8, 2023 at 8:04
  • Thank you I have now managed to clip the DEM file extents and compressed it, exporting it as a smaller geotif (jpg). It all looks great in QGIS but the small DEM geotif file does not display in QField.... Any suggestions ? Commented Jun 8, 2023 at 23:39
  • JPEG compression is for RGB rasters not floating point like a DEM, use LZW or Deflate compression for floating point GeoTIFF. Have a read of gdal.org/drivers/raster/cog.html compression options. COG (Cloud Optimized GeoTIFF) is a GeoTIFF with internal overviews. Commented Jun 9, 2023 at 3:14
  • Sorry but COG not really that practical for what I would like to do (and access issues with QGIS set up for QField use/syncrhonisation). If JPG compression was not working not sure why I would be able to see the significantly downsized DEM jpg. Still unable to see the relevant DEM file in QField (and no errors) Commented Jun 9, 2023 at 21:21

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