3.4.5.8. Cross classification

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cross_classification Cross classification

This tab allows for the calculation of a cross classification raster and matrix. Classification is compared to a reference raster or reference vector (which is automatically converted to raster). This is useful for calculating the area for every combination between reference classes and classification values. If a vector is selected as reference, it is possible to choose a field describing class values.

The output is a cross raster that is a .tif file where pixel values represent the categories of comparison (i.e. combinations identified by the CrossMatrixCode) between the classification and reference. Also, a text file containing the cross matrix (i.e. a .csv file separated by tab) is created with the same name defined for the .tif file.

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.

3.4.5.8.1. Input

  • Select the classification input_list: select a classification raster (already loaded in QGIS);
  • reload: refresh layer list;
  • checkbox Use value as NoData input_number: if checked, NoData value will be excluded from the calculation;
  • Select the reference vector or raster input_list: select a raster or a vector (already loaded in QGIS), used as reference layer;
  • reload: refresh layer list;
  • Vector field input_list: if a vector is selected as reference, select a vector field containing numeric class values;
  • BATCH batch_tool: add this function to the Batch;
  • RUN run: choose the output destination and start the calculation; the cross matrix is displayed in the tab Output and the cross raster is loaded in QGIS;