3. Classification erosion

_images/classification_erosion_tab.jpg

classification_erosion Classification erosion

This tab allows for removing the border of a class patch (erosion), defining the class values to be eroded and the number of pixels from the border. It is useful for classification refinement.

This tool supports virtual raster output; if the output file name ends with .vrt then the output is created as virtual raster composed of as many .tif files as the number of CPU threads defined in System; for large rasters this can speed up the process.

3.1. Classification erosion

  • Select the classification input_list: select a raster (already loaded in QGIS);

  • reload: refresh layer list;

  • Class values input_text: set the class values to be eroded; class values must be separated by , and - can be used to define a range of values (e.g. 1, 3-5, 8 will select classes 1, 3, 4, 5, 8); if the text is red then the expression contains errors;

  • Size in pixels input_number: number of pixels to be eroded from the border;

  • checkbox Circular optional: if checked, the erosion will be circular (e.g. a square patch will be eroded into a circle);

  • BATCH batch_tool: add this function to the Batch;

  • RUN run: choose the output destination and start the calculation;