GeometricMedian

Available with Image Analyst license.

Summary

Calculates the geometric median across pixels in a time series of multiband imagery.

Discussion

For more information about how this function works, see the Geometric Median function.

The referenced raster dataset for the raster object is temporary. To make it permanent, you can call the raster object's save method.

Syntax

GeometricMedian (rasters, epsilon, {max_iteration}, {extent_type}, {cellsize_type})

Parameter	Explanation	Data Type
rasters [rasters,...]	The input multiband rasters.	List
epsilon	The convergence value between two consecutive iterations. When epsilon is less than or equal to the specified value, the iteration will stop, and the result of the last iteration will be used. (The default value is 0.001)	Double
max_iteration	The maximum number of iterations to complete. The computation will end once this value is reached, regardless of the epsilon setting. (The default value is 10)	Integer
extent_type	Specifies the processing extent for the output raster. FirstOf—Use the extent of the first input raster to determine the processing extent. IntersectionOf—Use the extent of the overlapping pixels to determine the processing extent. This is the default. UnionOf—Use the extent of all the rasters to determine the processing extent. LastOf—Use the extent of the last input raster to determine the processing extent. (The default value is IntersectionOf)	String
cellsize_type	Specifies the cell size to use in the output raster. FirstOf—Use the first cell size of the input rasters. This is the default. MinOf—Use the smallest cell size of all the input rasters. MaxOf—Use the largest cell size of all the input rasters. This is the default. MeanOf—Use the mean cell size of all the input rasters. LastOf—Use the last cell size of the input rasters. (The default value is MaxOf)	String

Return Value

Data Type	Explanation
Raster	The output raster object.

Code sample

GeometricMedian example

This example calculates the geometric median from a collection of Landsat images.

# Import system modules
import arcpy
from arcpy.ia import *

# Check out the ArcGIS Image Analyst extension license
arcpy.CheckOutExtension("ImageAnalyst")

# Construct a collection from a mosaic dataset
rc = RasterCollection(r'C:\data.gdb\time_series_landsat_images')

#Execute
geomedian = arcpy.ia.GeometricMedian(rc, {"epsilon": 0.001, "max_iteration": 5, "extent_type":"UnionOf", "CellsizeType": "FirstOf"})

# Save the output
geomedian.save("C:/arcpyExamples/outputs/geomedian_raster.crf")