Function Description
NDWI (Normalized Difference Water Index), Normalized Difference Water Index. It is generally used to extract the water information in the image. Compared with NDVI, it can effectively extract the water content of the vegetation canopy.When the vegetation canopy is under water stress, the NDWI index can respond in time, which is of great significance for drought monitoring. Using NDWI to extract the water body with more building background, such as the water body in the city, the effect will be poor.
NDWI is the normalized ratio index based on Green Band and Near Infrared Band, and the expression is: NDWI = (G-NIR)/ (G + NIR), where G is Green Band and NIR is the reflectance of Near Infrared Band.
The NDWI index can be calculated through a variety of satellite remote sensing data. Before using the function, the user needs to understand the remote sensing Data Type and distinguish the band meaning of the remote sensing data. For a description of common satellite Remote Sensing Imagery bands, please refer to Data description .
Function entrance
- Data tab-> Data Processing-> Grid-> NDWI.
- Toolbox-> Data Processing-> Grid-> NDWI.
Parameter Description
- Green Band: Set the green band involved in the calculation. If the image is a single-band Dataset, select the Green Band Data set; if it is a multi-band Dataset, select the Green Band in the Dataset.
- Near Infrared Band: Set the Near Infrared Band participating in the calculation. If the image is a single-band Dataset, select the Near-Infrared Band Data set; Select the Near Infrared Band in the Dataset if it is a multiband Dataset.
- Result Data: Set the Datasource and Dataset where the Result Dataset is located, and the program will set the Green Band and Near Infrared Band. Generates a grid Result Dataset according to the NDWI expression.
Application example
The Landsat 8Satellite Image data of a certain area in June 2013 and June 2018 are available. By calculating the NDWI index of the same area in different years and viewing the water body information, the following results are obtained.
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| Figure of NDWI results in 2013 | Figure of NDWI results in 2018 |
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