a) Besides the surface reflection, we have to worry about the atmosphere getting

Question

a) Besides the surface reflection, we have to worry about the atmosphere getting in the way. In particular, the atmosphere can attenuate the solar reflected light from the surface. Keeping this in mind, which Landsat channels should you avoid. Hint. Look up atmospheric transmission window. If a window does not transmit well, explain what in the atmosphere is causing the problem.

b) We also have to worry about the fact that solar illumination can be different so that even for the samematerial, the reflectance at different illumination angles may modify the reflectance. How can our vegetation indicator considered in question 5 help eliminate this concern?

(question 5:Using multiple channels, which LANDSAT channels do you think (do not look it up but reason it out) would be the best to observe vegetation and separate it from both soils and man-made surfaces ? 0

Explanation / Answer

(A) As far as reflection is concern we must know about the atmospheric windows. Our atmosphere allows certain wavelength to pass through it which we termed is atmospheric windows. We must have the particular frequency band for the transmission through atmosphere. If the atmosphere has clouds , it would not allow visible light or any other wavelength range of em spectra other than microwave. So for transmission make sure that the atmosphere is clear.

(B) In the LANDSAT image the vegetation looks red in color. We use false color composite to differentiate between two objects. Soil appeares bright or light yellow in color and manmade objects (town or settlements) seems blue in color. With the help FCC we can differenciate between two objects. Thus two different features with same reflectance or may not can be interpeted using FCC.

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