Resampling raster resolution

Resampling an image allows you to change the current resolution of an image to a different resolution. Resampling to a lower resolution, also known as downsampling, requires you to remove pixels from the image while maintaining the geospatial referencing integrity of the dataset. In the QGIS Processing Toolbox, the gdalogr:warpproject algorithm is used, which is the same as the algorithm used for reprojection.

Getting ready

We will again use the SatImage raster available at https://geospatialpython.googlecode.com/files/SatImage.zip.

Place this raster in your /qgis_data/rasters directory.

How to do it...

There's an extra step in this process, where we will get the current pixel resolution of the raster as a reference to calculate the new resolution and pass it to the algorithm. To do this, we need to perform the following steps:

1. Start QGIS.

2. From the Plugins menu, select Python Console.

3. Import the processing module:

   import processing
   

4. Load and validate the raster layer:

   rasterLyr...