NDMI

Synthèse

Calculates the Normalized Difference Moisture Index (NDMI) from a multiband raster object and returns a raster object with the index values.

Discussion

The Normalized Difference Moisture Index (NDMI) is sensitive to the moisture levels in vegetation. It is used to monitor droughts and fuel levels in fire-prone areas. It uses NIR and SWIR bands to create a ratio designed to mitigate illumination and atmospheric effects.

NDMI = (NIR - SWIR1)/(NIR + SWIR1)

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.

Syntaxe

NDMI (raster, {nir_band_id}, {swir1_band_id})

Paramètre	Explication	Type de données
raster	The input raster.	Raster
nir_band_id	The band ID of the near-infrared band. The ID index uses one-based indexing. (La valeur par défaut est 5)	Integer
swir1_band_id	The band ID of the shortwave infrared band. The ID index uses one-based indexing. (La valeur par défaut est 6)	Integer

Valeur renvoyée

Type de données	Explication
Raster	The output raster object with the NDMI values.

Exemple de code

NDMI example

Calculates the Normalized Difference Moisture Index for a Landsat 8 image.

from arcpy.sa import *
out_ndmi_raster = NDMI("landsat8.tif", 5, 6)
out_ndmi_raster.save("C:/arcpyExamples/outputs/NDMI.tif")

NDMI example

Calculates the Normalized Difference Moisture Index for a Landsat 8 image.

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

# Set the analysis environments
arcpy.env.workspace = "C:/arcpyExamples/data"

# Set the local variables
in_raster = "landsat8.tif"

# Execute NDMI function
out_ndmi_raster = NDMI(in_raster, 5, 6)

# Save the output
out_ndmi_raster.save("C:/arcpyExamples/outputs/NDMI.tif")