CCDWM

Description

CCDWM combines the results from multiple change detection techniques in a weighted manner. Areas indicating change for multiple techniques (intensity, coherence, Wishart) are much more likely to indicate real changes. For each change file, the user weights are applied to the change ranking channel and the results summed. Areas ranking high for all change metrics are highlighted. For convenience, the weighted values are ranked from 0 (lowest value) to 100 (highest value).

Parameters

Name	Type	Length	Value range
Input Layers: Input change metric rasters *	Raster port	2 - 1
Weights	Float	0 - 1024
Output: Output weighted change raster *	Raster port	1 -

* Required parameter

Parameter descriptions

Input Layers: Input change metric rasters

Specifies a list of co-registered change metric channels. All input data must be in the same projection and pixel size.

It is expected that the input change metric rasters have been produced by CCDINTEN, CCDPHASE, or CCDWISH.

Weights

Optionally specifies a list of zero- or positive-valued weights to be applied to ranked change metrics, as defined by the input image. The first weight will be applied to the first image, the second weight to the second image, and so on. You must specify the same number of weights as there are image files to compare; otherwise, CCDWM will error and abort. By default the images are weighted equally, with a value of 1 for each image.

Output: Output weighted change raster

Specifies the name of the output file to be created. This file will contain the weighted metric in channel 1 and the weighted metric cumulative percentile values in channel 2.

The specified file must not already exist.

Details

CCDWM rates the results of different change detection techniques to produce a unique map of overall change. Depending on the change and features of interest, different change detection techniques might enhance different changes. For instance, when the backscatter in two images is very similar but the phase between the co-polarization has changed, the Wishart test statistic is much more sensitive to the differences than test statistics based only on the intensity. However, depending on the gradient of change, you might want to use results from both CCDINTEN and CCDWISH but weight them differently to determine the overall changes.