Reclassifying rasters

Raster data sets often have hundreds or thousands of values. For an analysis, you may need to synthesize the data into meaningful categories. For example, elevation may be an important input in a habitat model for species X. However, you may only be interested in identifying several broad elevation thresholds that help to define the habitat. In the following example, you will use the elevation.tif sample data. You will reclassify the elevation data into several categories: less than 2000 meters, 2000 to 2500 meters, and greater than 2500 meters. This will result in a raster with three values: one for each group of elevation values. The following steps outline how to use the r.recode GRASS tool (found in the processing toolbox) to accomplish this:

1. Load elevation.tif and set the project's CRS to EPSG: 26912.

2. Turn on the Processing plugin (by navigating to Plugins | Manage and Install Plugins) if it is not enabled.

3. Open the Processing panel by clicking on Toolbox under Processing...