Normalized Difference Water Index (NDWI) is used to monitor changes related to water content in water bodies proposed by McFeeters (1996).
Same as mentioned in
Computed NDWI product
1. NDWI = (r_green - r_nir) / (r_nir + r_green)
where, "r_" denotes TOA reflectance band.
2. There is another NDWI to monitor changes in water content of leaves proposed by Gao (1996). User should understand the requirements and run accordingly.
Other important notes are mentioned in
McFeeters, S.K. (1996) The Use of the Normalized Difference Water Index (NDWI) in the Delineation of Open Water Features. International Journal of Remote Sensing, 17, 1425-1432. doi:10.1080/01431169608948714.
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library (raster) library (rgdal) # Finding the path of the sample satellite image directory. # User may define paths directly like "/home/ur_folder" or "C:/ur_folder" path <- system.file ("TM_sample", package = "ASIP") shapefil <- paste0 (path, "/test.shp") op <- ndwi (directory = path, crop = "y", ext2crop = shapefil)
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