The Variance-Covariance operation calculates variances and covariances of a number of raster maps in a map list. The variance is a means to express the variation of pixel values within a single raster map, i.e. a measure of the variation to the mean of the DN (Digital Number) values in a raster map. The covariance is a measure to express the variation of pixel values in two raster maps. It denotes the joint variation to the common mean of pixel values of the maps.
Dialog box options:
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Map list: |
Select an input map list (open the list box and select the desired map list, or drag a map list from the Catalog into this list box) or create a new map list by clicking the create button. All raster maps in the map list must use the Image domain or the same value domain and must have the same georeference. |
When you click the OK button, the covariance matrix is calculated and shown. The matrix is not stored as a separate object, but the matrix values are stored by the object definition file of the map list (.MPL). To show the matrix once more after you closed the matrix window, you have to perform the operation again.
See also: