How to Compress a GeoTIFF Orthomosaic in QGIS


If you have processed your dataset using the Propeller platform, you can download a high-resolution orthomosaic in GeoTIFF format in your site's coordinate system. If the GeoTIFF file size is too large to use with your software, you can use QGIS to compress the file.

As a prerequisite, you must have QGIS installed on your computerBefore you start the compression process, you need to load your GeoTIFF into QGIS by either dragging and dropping it into QGIS or using the Add Raster Layer function from the Layer menu. 

Compressing GeoTIFFs using QGIS can be achieved using different methods.

Exporting the file and re-scaling the pixel size

This is the easiest method; you just need to export the original GeoTIFF with a bigger pixel size. This will allow you to save some space on your computer. However, the output file will have a reduced resolution where you may lose some details.

 

 

Aligning the file with the Lanczos algorithm and re-scaling the pixel size


Aligning the raster is a very similar method to the exporting one. However, it can use different algorithms to re-sample the pixel size. The Lanczos algorithm gives the best results, and you will not lose as much of the original photo quality.

 

 

Compressing the file with JPEG compression (recommended)


The last method is the actual compression. It uses JPEG compression, but the output file will remain a GeoTIFF. As you don't change the pixel size, you do not lose the resolution and accuracy quality, which, in our opinion, makes this method the best choice.

 

 

The table below presents how the size of the input file changes over Aligning raster and JPEG compression:

 


You should also be aware of the downsides of the compression in QGIS:

  • Change of the pixel size while exporting or aligning raster 
    • The spatial resolution of the output file is changed, so the file may not be a high-resolution file anymore, and as a result, you may lose some of the information or details.
  • It can be time consuming
    • Depending on the file's original size, it can take up to 2 hours to compress the input file. 
  • Some third-party software may not be able to open tiled or larger TIFF files 
    • When creating output files with JPEG compression, we choose these parameters. You should be aware of the limitations that some software may have.

I still can't do it!

We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient. If you're stuck, you can connect with our support team by clicking the support button on the top right corner of your user portal.