Land in Focus – Basics of Remote Sensing

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  • Demeke Alemayehu Semegn

    January 20, 2022 at 1:30 pm

    wow, I have reaching out on remote sensing. That is my interesting to know about principles

  • Robynn Robyn

    November 24, 2021 at 10:18 am

    For darker pixels, is it safe to assume that this area is either in shadow or extremely flat? Is there a method of telling the difference?

    • Kai Heckel

      November 24, 2021 at 1:59 pm

      thanks for reaching out to us.

      Firstly, the pixel brightness is not primarily depending on the spatial resolution but rather on the spectral bands and the radiometric resolution. Depending on the wavelength of the used imaging bands (e.g., NIR), a pixel will appear brighter or darker depending on its reflectance/absorption characteristics in relation to the given wavelength. Shadows influence some wavelengths more than others (in the optical domain) and will usually reduce the pixel reflectance to some extent.

      For example, is the reflectance (%) of a grass pixel (vital) significantly lower in the visible spectrum the reflectance of a bare soil pixel. Consequently, vital vegetation will appear darker than bare soil in this image band without the influence of shadow or topographic influences.

      So keep in mind to always take into account your wavelength and the characteristics of a given pixel that was sensed.

      Hope this helps.

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