# NDSI

## サマリー

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

## 説明

The Normalized Difference Snow Index (NDSI) is designed to use MODIS (band 4 and band 6) and Landsat TM (band 2 and band 5) for identification of snow cover while ignoring cloud cover. Since it is ratio based, it also mitigates atmospheric effects.

`` NDSI = (Green - SWIR) / (Green + SWIR)``

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.

## 構文

`NDSI (raster, {green_band_id}, {swir_band_id})`
 パラメーター 説明 データ タイプ raster The input raster. Raster green_band_id The band ID of the green band. The ID index uses one-based indexing.(デフォルト値は次のとおりです 4) Integer swir_band_id The band ID of the shortwave infrared band. The ID index uses one-based indexing.(デフォルト値は次のとおりです 6) Integer

 データ タイプ 説明 Raster The output raster object with the NDSI values.

## コードのサンプル

NDSI example

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

``````import arcpy

NDSI_raster = arcpy.ia.NDSI("Landsat8.tif", green_band_id = 4, swir_band_id = 6)``````
NDSI example

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

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

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

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

# Execute NDSI function
out_ndsi_raster = NDSI(in_raster, 4, 6)

# Save the output
out_ndsi_raster.save("C:/arcpyExamples/outputs/NDSI.tif")``````