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I have been provided with two data sets of the same area, one with normal RGB bands and one with NIR data. My problem is that since the NIR data is given as 3 bands, i am not sure how I should interpret this.

I am guessing that its normal in some data acquisition areas to collect NIR data with a DSL camera with some filters removed and thats why the data is captured over 3 bands. (but i really dont know much about this).

How do i transform the 3 bands of nir data into the one I need for my NDVI calculation?

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    All 3 bands cover the same range of wavelength?
    – dof1985
    May 1, 2015 at 15:58
  • I would not know. Thats why I ask here to get an idea of what is commonly done. There are different values in each band, so i do not think so. May 1, 2015 at 16:07
  • It seems odd and it is hard to tell. My guess is that thos are different satellite bands. Note that NIR can be divided to several ranges, and it mainly depands on the data provider (e.g. satellite sensors). Thus you might consider to follow up with the source provider to get meta data which should include such information.
    – dof1985
    May 1, 2015 at 16:22
  • I know that its collected from a plane with a DSL camera with some NIR filters. Not a satellite. May 1, 2015 at 16:24
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    I still suggests you contact the data provider. There are many kinds of filters, which perform differently, Thus it would be hard to tell what wavelength each band stands for. Also the brand and model of the camera used might spread some light, since those are also vary in IR sensitivity.
    – dof1985
    May 1, 2015 at 16:44

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Sometimes distributors drop the blue band and provide only the nIR, red and green bands so that the end user can view the data as a false color composite image. Let's assume the distributor did that. There are several ways you can deduce which bands are which, especially at the red and nIR wavelengths, using basic remote sensing principles. For example, we know that EMR in the nIR portion of the spectrum is highly reflected off healthy green vegetation and highly absorbed in water. We also know that EMR in the red portion of the spectrum is generally absorbed by healthy green vegetation. This difference effect is what makes the NDVI such a valuable vegetation index.

The following examples show the spectral properties (measured in DN here) of water in the first screenshot and healthy green vegetation in the second screenshot. Based on this analysis, we can tell that the nIR band is layer 4 and the red band is layer 1.


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