Focal Statistics
Open Table of Contents ToolBox Implementation
Derives value for the output calls from a neighborhood of cells centered in the output cell. The neighborhood is with user defined shape (square or circle) and size (width or diameter) in number of cells.

Neighborhoods:
Square Circle
Width = 3 Width = 5 Diameter = 3 Diameter = 5

Inputs:

  • Input raster dataset
  • Output raster name and format
  • Neighborhood shape
    • Square
    • Circle
  • Neighborhood size (width for square and diameter for circle) in pixels/number of cells. The size needs to be an odd number in order to place the cell for which the calculations are performed in the center of the neighborhood.
  • Statistics type .
    • Integer and Floating point rasters
      • Sum - the sum of the cell values within the neighborhood
      • Min - the minimum values within  the neighborhood
      • Max  - the maximum value within  the neighborhood
      • Range - the range of values within  the neighborhood
      • Mean - the average of the values within  the neighborhood
      • STD - the standard deviation of the values in  the neighborhood
      • Median - the median value in  the neighborhood
    • Integer rasters only
      • Major - the majority value (the value that appears most times in  the neighborhood).
      • Minor - the minority value (the value that appears least times in  the neighborhood).
      • Variety - variety (the number of unique values in  the neighborhood).

Output:

  • A raster with type depending on the type of the input raster and the type of statistics performed.
    • Floating point input raster - Floating point output
    • Integer input raster
      • MEAN or STD statistics type - Floating point output
      • Any other type statistics - Integer output

Example:

Neighborhood

 Results for the center cell
  • Sum = 49
  • Min = 2
  • Max = 9
  • Range = 7
  • Mean = 5.44
  • STD = 2.54
  • Median = 5
  • Major = 3
  • Minor = 2
  • Variety = 7

Notes:

  • Initially the name of the output raster defines the raster format
    • no extension specified - ESRI binary GRID
    • .img extension (for example raster1.img) - ERDAS IMAGINE image.
    • .tif extension (for example raster1.tif - Tagged Image File Format (TIFF) image.
  • The initial output raster format can be changed by selecting the desired output in the dialog.
  • Currently only file based rasters are supported. Rasters cannot be stored in a GeoDatabase. After you get the desired result, you can export the raster to a GeoDatabase using the standard ArcGIS tools.
  • The input raster must be in a projected coordinate system.

ToolBox implementation

Command line syntax

ETS_GPFocalStatistics <Input Raster>  <Out Raster> <Statistics Type> <Neighborhood Type> <Neighborhood Size>

Parameters

Expression Explanation
<Input Raster> A Raster dataset or Raster layer
<Out Raster> A String - the full name of the output raster (A raster with the same full name should not exist). The output raster type depends on the extension of the output file(see Notes above)
<Statistics Type> A String - the type of the statistics to be calculated.  Valid values
  • Sum
  • Min
  • Max
  • Range
  • Mean
  • STD
  • Median
  • Major
  • Minor
  • Variety
<Neighborhood Type> A String - the neighborhood type. Valid values: Square and Circle
<Neighborhood Size> An integer - the side of the square or the diameter of the circle in pixels/number of cells. This should be an even number.

Scripting syntax

ETS_GPFocalStatistics (Input Raster, Out Raster, Statistics Type, Neighborhood Type, Neighborhood Size)

See the explanations above:
<> - required parameter
{} - optional parameter

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Copyright: Ianko Tchoukanski