pktools  2.6.7
Processing Kernel for geospatial data

program to compare two raster image files


Usage: pkdiff -i input -ref reference

Options: [-ln layer] [-b band] [-cm] [-lr attribute] [-c name -r value]* [-nodata value]* [-m mask] [-msknodata value]*

Advanced options: [-o output] [-f OGR format] [-lc attribute] [-bnd value [-hom] [-circ]] [-ct colortable] [-co NAME=VALUE]*


The utility pkdiff compares two datasets. The reference can either be a raster or a vector, but the input must be a raster dataset. In case the reference is a raster dataset, a pixel by pixel comparison is performed. With no further options, the utility reports if the rasters are identical or different. If required, an output raster dataset can be written with a qualitative information per pixel: 0 (input=reference), 1 (input>reference) or 2 (input<reference). If, however, the reference is a vector dataset, it must consist of point features. Polygon features are automatically converted to the centroid points before analyzing.

A typical use of the utility is to assess the accuracy of an input raster land cover map, based on a reference vector dataset. The reference dataset must contain an attribute (label) for each class. A confusion matrix is produced if the option -cm|–confusion is set. Here too, an output dataset can be written, which will be a vector dataset in this case. It contains the reference feature points with the extracted data value of the raster input dataset as a new attribute.



Some examples how to use pkdiff can be found here