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I have photo created by UAV, and I want to calculate bNDVI:

(NIR-blue)/(NIR+blue)

I have these bands (filter is ok -100%). So using QGIS I have values -0,1-> 0,3 - but bNDVI must be from 0,65->0,80 (look at picture): enter image description here

I have problems with the calculation; on QGIS, ArcGIS, and pix4D I get same result. I thought that I had to multiply val/256*2-1 but didn't work again. Color depth is 24. Can anyone help me?

  • Using 256 as a constant is probably valid when colour depth is 8 (2^8=256), so try using 2^24 which is 16777216 – wfgeo Mar 30 '18 at 14:54
  • 24 means 8bit for each color – Mr.DontKnow Mar 30 '18 at 15:00
  • This may be due to illumination variance in your images. Also, that chart you are trying to replicate (I think I recall it from a paper), do you have the same setting used in their paper? In my experience NDVI can vary greatly depending on your image quality, cameras and filters used, the spectral range your NIR filters have, etc. – DarkCygnus Mar 31 '18 at 4:43
  • @DarkCygnus and how to calculate it, If I send you a picture, can you calculate it? or need more information? – Mr.DontKnow Apr 3 '18 at 15:16
  • @Mr.DontKnow perhaps, ping me on chat if you like. does your tiff have many vegetation present or few? Perhaps the NDVI SAVI can help – DarkCygnus Apr 3 '18 at 15:55

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