xrspatial.multispectral.ndwi#

xrspatial.multispectral.ndwi(green_agg: DataArray, nir_agg: DataArray, name='ndwi')[source]#

Computes Normalized Difference Water Index (NDWI).

NDWI highlights open water features while suppressing vegetation and soil signal.

Parameters:

green_agg (xr.DataArray) – 2D array of green band data. (Landsat 8: Band 3) (Sentinel-2: Band 3)
nir_agg (xr.DataArray) – 2D array of near-infrared band data. (Landsat 8: Band 5) (Sentinel-2: Band 8)
name (str, default='ndwi') – Name of output DataArray.
Alternatively
first (a single xr.Dataset may be passed as the)
Dataset (argument with keyword arguments mapping band names to)
example:: (variables. For) – ndwi(ds, green=’B3’, nir=’B8’)

Returns:

ndwi_agg – 2D array of ndwi values in the range [-1, 1]. All other input attributes are preserved.

Return type:

xr.DataArray of same type as inputs

References

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(7), pp.1425-1432.

Examples

>>> import numpy as np
>>> import xarray as xr
>>> from xrspatial.multispectral import ndwi
>>> green = xr.DataArray(np.array([[600., 500.], [400., 300.]]))
>>> nir = xr.DataArray(np.array([[300., 400.], [500., 600.]]))
>>> ndwi(green, nir).values
array([[ 0.33333334,  0.11111111],
       [-0.11111111, -0.33333334]], dtype=float32)