The nonoverlapping neighbourhood functions, or block functions, allow statistics to be calculated in a specified nonoverlapping neighbourhood. Variations of the overlapping neighbourhood statistics function are the high- and low-pass filter functions to smooth and accentuate data. For example, you may want to find the mean or maximum value in a three-by-three-cell neighbourhood. Overlapping neighbourhood functions, or focal functions, generally calculate a specified statistic within the neighbourhood. Neighbourhood statistics can be overlapping or nonoverlapping. The statistics calculated for the neighbourhood act as a moving window that scans across the data. Neighbourhood functions create output values for each cell location based on the value for that location and the values identified in a neighbourhood specified by the user. Based on this information, a developer may choose an alternate location for a new golf course because of the decreased water supply that will occur in the near future for this area. When computing a local function, you can combine input rasters, calculate a statistic, or evaluate a criterion for each cell in an output raster based on the values of each cell from multiple input rasters.įor example, by using cell-based statistics, the user can visualize where a desert may spread over a 10-year period. In a local function, the value at each location on the output raster is a function of the input values at that location.

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