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How is NDWI calculated?
NDWI = (G-NIR)/(G+NIR) The Normalized Difference Water Index (NDWI) is derived from the Near-Infrared (NIR) and Green (G) channels. This formula highlights the amount of water in water bodies. An alternate method of calculation uses the NIR and Short Wave Infrared (SWIR) channels [(NIR-SWIR)/(NIR+SWIR)].
Which bands are used to calculate the NDWI for an area?
Calculation of NDWI The NDWI is a remote sensing based indicator sensitive to the change in the water content of leaves (Gao, 1996). NDWI is computed using the near infrared (NIR – MODIS band 2) and the short wave infrared (SWIR – MODIS band 6) reflectance’s.
What does NDWI show?
The NDWI index for assessing risk of fire is used to determine the presence of moisture in vegetation cover. Higher NDWI values indicate sufficient moisture, while a low value indicates water stress.
Is NDVI a band ratio?
These spectral reflectances are themselves ratios of the reflected over the incoming radiation in each spectral band individually, hence they take on values between 0.0 and 1.0. NDVI is functionally, but not linearly, equivalent to the simple infrared/red ratio (NIR/VIS).
How to calculate NDVI and ndwi for Landsat 7?
However, NDBI calculation is simple and easy to derived. NDVI can be calculated by following formula. NDBI = (SWIR – NIR) / (SWIR + NIR) For Landsat 7 data, NDBI = (Band 5 – Band 4) / (Band 5 + Band 4) For Landsat 8 data, NDBI = (Band 6 – Band 5) / (Band 6 + Band 5) Also, the Normalize Difference Build-up Index value lies between -1 to +1.
Which is the panchromatic band in Landsat 7?
Panchromatic band is used for increase the resolution of data. Landsat 7 data having total of 8 band while Landsat 8 data having 11 bands. For analysis of Normal Difference Vegetation Index (NDVI), Normal Difference Built-up Index (NDBI) and Normal Difference Water Index (NDWI), only four bands are used (Green, Red, NIR, SWIR).
Can you divide Landsat 8 data by 10, 000?
Dividing Landsat 8 data by 10,000 (or multiplying by 0.0001) is useful to scale individual bands data, but useless to calculate NVDI, NDWI or NDSI since the results are the same after scaling or not. In all cases, data <0 or >10,000 must be ignored in original band data. Can you help by adding an answer?
How to calculate ndwi using ls 5 images?
There are certainly more elegant ways to do, but it should work… O Often it is just a very small number of cells e.g. at the image margin out of value range. Pl find the attachment of my print screens for the whole procedure of calculating NDWI and NDSI using LS 5 images. This may help you to find the solution of your problem.