VARI

Summary

Calculates the Visible Atmospherically Resistant Index (VARI) from a multiband raster object and returns a raster object with the index values.

Discussion

The Visible Atmospherically Resistant Index (VARI) is designed to emphasize vegetation in the visible portion of the spectrum, while mitigating illumination differences and atmospheric effects. It is ideal for RGB or color images; it utilizes all three color bands.

VARI = (Green - Red) / (Green + Red – Blue)

• Green = pixel values from the green band
• Red= pixel values from the red band
• Blue = pixel values from the blue 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

VARI (raster, {red_band_id}, {green_band_id}, {blue_band_id})

Parameter	Explanation	Data Type
raster	The input raster.	Raster
red_band_id	The band ID of the red-edge band. The band ID index uses one-based indexing. (The default value is 3)	Integer
green_band_id	The band ID of the green band. The ID index uses one-based indexing. (The default value is 2)	Integer
blue_band_id	The band ID of the blue band. The ID index uses one-based indexing. (The default value is 1)	Integer

Return Value

Data Type	Explanation
Raster	The output raster with the VARI values.

Code sample

VARI example

Calculates the Visible Atmospherically Resistant Index for a Landsat 8 image.

import arcpy

VARI_raster = arcpy.ia.VARI("Landsat8.tif",4,3,2)