Geoscience Reference
In-Depth Information
12.6 pkdiff
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 (Congalton 1991) 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. An example
of this usage is provided in the case study on accuracy assessment in Sect. 17.3.4 .
<
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]*
-i|--input
Input raster dataset.
-ref|--reference
Reference (raster or vector) dataset.
-ln|--ln
Layer name(s) in sample. Leave empty to select all (for vector reference datasets
only).
-b|--band
Input raster band (default: 0).
-cm|--confusion
Create confusion matrix (to std out) (default: false).
-lr|--lref
Attribute name of the reference label (for vector reference datasets only) (default:
label).
-c|--class
List of class names.
-r|--reclass
List of class values (use same order as in classname option).
 
 
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