ClayMinerals

Summary

Calculates the Clay Minerals (CM) ratio from a multiband raster object and returns a raster object with the index values.

Discussion

The clay minerals ratio is a ratio of the SWIR1 and SWIR2 bands. This ratio leverages the fact that hydrous minerals such as the clays, alunite absorb radiation in the 2.0–2.3 micron portion of the spectrum. This index mitigates illumination changes due to terrain since it is a ratio.

\(Clay \space Minerals \space Ratio \space = \space SWIR1 \space / \space SWIR2\)

• SWIR1 = pixel values from the short-wave infrared 1 band

• SWIR2 = pixel values from the short-wave infrared 2 band

For information about other multiband raster indexes, see the Band Arithmetic raster 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

ClayMinerals(raster, {swir1_band_id}, {swir2_band_id})

Parameter	Explanation	Data Type
raster	The input raster.	Raster
swir1_band_id	The band ID of the shortwave infrared 1 (SWIR1) band. The band ID index uses one-based indexing. The default value is 6.	Integer
swir2_band_id	The band ID of the shortwave infrared 2 (SWIR2) band. The band ID index uses one-based indexing. The default value is 7.	Integer

Return value

Data Type	Explanation
Raster	The output raster object with the Clay Minerals ratio values.

Code sample

ClayMinerals example

Calculates the Clay Minerals ratio for a Sentinel-2 image.

import arcpy

ClayMinerals_raster = arcpy.ia.ClayMinerals("Sentinel2.tif", 11, 12)