I am trying to calculate NDWI from Landsat-8 Band3(range:-113 to 11785) and Band5(range -89 to 12960) but the range of the resultant NDWI image is not valid (range: -215.181 to 1151.02). What is the possible workaround?

  • And what makes you think that the range that you are seeing in the resultant image is incorrect? Negative input values in a NDWI calculation can lead to all sorts of strange values, however, the main bulk of your values should be between -1 and 1. Perhaps take a look at the distribution of values? – Mikkel Lydholm Rasmussen Jun 8 '20 at 10:27
  • @MikkelLydholmRasmussen NDWI valid range is between -1 to 1. Secondly, when I check the pixel value of the water bodies its incorrect. The pixel value of water should be greater than 0. – studysmart Jun 8 '20 at 10:35
  • And are you using atmospherically corrected data? – Mikkel Lydholm Rasmussen Jun 8 '20 at 10:39
  • @MikkelLydholmRasmussen Yes I am using Landsat-8 surface reflectance product from USGS. – studysmart Jun 8 '20 at 10:45
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    Then you shouldn't be using poorly atmospherically corrected data. I suggest either atmospherically correcting it yourself, or just use uncorrected data for your study. – Mikkel Lydholm Rasmussen Jun 8 '20 at 11:42

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