NAME¶

pkdiff - program to compare two raster image files

SYNOPSIS¶

pkdiff
-i input -ref reference [options] [advanced options]

DESCRIPTION¶

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.

OPTIONS¶

-i filename, --input filename

Input raster dataset.

-ref filename, --reference filename

Reference (raster or vector) dataset

-ln layer, --ln layer

Layer name(s) in sample. Leave empty to select all (for vector reference datasets only)

-b band, --band band

Input raster band

-cm, --confusion

Create confusion matrix (to stdout)

-lr attribute, --lref attribute

Attribute name of the reference label (for vector reference datasets only)

-c name, --class name

List of class names.

-r value, --reclass value

List of class values (use same order as in classname option).

-nodata value, --nodata value

No data value(s) in input or reference dataset are ignored

-m mask, --mask mask

Use the first band of the specified file as a validity mask. Nodata values can be set with the option --msknodata.

-msknodata value, --msknodata value

Mask value(s) where image is invalid. Use negative value for valid data (example: use -t -1: if only -1 is valid value)

-v level, --verbose level

verbose level

Advanced options

-o output, --output output

Output dataset (optional)

-f OGRformat, --f OGRformat

OGR format for output vector (for vector reference datasets only)

-of GDALformat, --oformat GDALformat

Output image format (see also gdal_translate(1)). Empty string: inherit from input image

-lc attribute, --lclass attribute

Attribute name of the classified label (for vector reference datasets only)

--commission value

Value for commission errors: input label < reference label

-bnd value, --boundary value

Boundary for selecting the sample (for vector reference datasets only)

-hom, --homogeneous

Only take regions with homogeneous boundary into account (for reference datasets only)

-circ, --circular

Use circular boundary (for vector reference datasets only)

-ct colortable, --ct colortable

Color table in ASCII format having 5 columns: id R G B ALFA (0: transparent, 255: solid).

-co NAME=VALUE, --co NAME=VALUE

Creation option for output file. Multiple options can be specified.

EXAMPLE¶

Check if two raster images are different (reports only if images are different or not)

pkdiff -i input.tif -ref reference.tif


      

Validate a classification map using points from a reference sample and report confusion matrix

pkdiff -i classificationMap.tif -ref referencePoints.tif -cm