AutoCorrelation calculates autocorrelation and semi-variogram values for a raster map. The autocorrelation of a raster map is generated by calculating the correlation between pixel values of a raster map and pixel values of the same raster map for different shifts (lags) in horizontal or vertical directions. The semi-variogram values which are a measure of the spatial variability within a raster map are calculated for the same shifts. The operation is a tool to obtain information on horizontal and vertical patterns in a raster map.
Dialog box options:
Input raster map: |
Select an input raster map. Open the list box and select the desired input map, or drag a raster map directly from the Catalog into this box. The raster map need to be a value map. |
Maximum pixel shift: |
Type a value for the maximum pixel shift (in pixels), i.e. the maximum separation distance between pixels until which correlation and semi-variogram values should be calculated. By making a graph of distance against for instance output experimental semi-variogram values, you can find until which distance, the values in the raster map are related to each other (in geostatistics, that distance is called the range). |
Output table: |
Type a name for the output table that will contain the autocorrelation and the experimental semi-variogram values for shifts of 1 pixel, 2 pixels, 3 pixels, etc. until the specified maximum pixel shift. |
Description: |
Optionally, type a description for the output table. The description will appear in the status bar of the Main window when moving the mouse pointer over the table in a Catalog, and in the title bar of a table window when the output table is displayed. If no description is supplied, the output table will use its own definition as description. |
When you click the Show button, the dependent output table will be defined, calculated and shown. When you click the Define button, the dependent output table will only be defined; if necessary the table will be calculated later, for instance when the table is opened to be displayed.
See also: