Chapter 8 — Question 3

In a change detection study, if there were images from different years but from the same
season, would it still be necessary to perform atmospheric corrections? Why or why not?

Answer

This depends on the specific application of this detection study. If the varia-
ble, parameter or property to be detected can only be evaluated from absolute
atmospherically corrected ground radiances, then it is necessary to perform an
absolute atmospheric correction where the results are atmospherically corrected
images in units of radiances. If the variable, parameter or property to be de-
tected is related to an image index without strict physical meaning (e.g. NDVI),
it is possible to use methods of reflective invariants to accommodate the same
atmosphere in all the images to allow the temporal comparison. In this case
atmospheric correction of each image is not necessary.

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