Geometric Median function

Available with Image Server

The Geometric Median function calculates the geometric median across pixels in a time series of multiband imagery.

Notes

This function reduces noise and outliers in time series imagery by calculating a geometric median pixel for each pixel array across the image stack. The algorithm maintains the spectral relationships between bands in the pixel spectra, so the output can be used in analysis, such as vegetation indices.

Clouds and shadows should be masked using the dataset QA band before applying this function.

If the input image is floating point, such as surface reflectance with values between 0 and 1, an epsilon value of 0.001 should produce quality results.

Parameters

Parameter name	Description
Rasters	The input multiband rasters.
Cell Size Type	Choose which cell size to use in the output raster. If all the input cell sizes are the same, all the options will yield the same results. First Of—Use the first cell size of the input rasters. Min Of—Use the smallest cell size of all the input rasters. Max Of—Use the largest cell size of all the input rasters. This is the default. Mean Of—Use the mean cell size of all the input rasters. Last Of—Use the last cell size of the input rasters.
Extent Type	Choose which extent should be used in the output raster: First Of—Use the extent of the first input raster to determine the processing extent. Intersection Of—Use the extent of the overlapping pixels to determine the processing extent. This is the default. Union Of—Use the extent of all the rasters to determine the processing extent. Last Of—Use the extent of the last input raster to determine the processing extent.
Maximum number of iterations	Specifies the maximum number of iterations to complete. The computation ends when this value is reached, regardless of the Epsilon setting.
Epsilon	Specifies the convergence value between two consecutive iterations. When epsilon is less than or equal to the specified value, the iteration stops, and the result of the last iteration is used.