Nadir Normalization vs. BREFCOR BRDF correction

[reseadmin]

What's the difference between nadir normalization and BRDF correction?

[reseadmin]

Nadir normalization is a statistical ajustment of across track brightness differences whereas the BREFCOR BRDF correction uses a physical BRDF model for surface cover dependent correction of anisitotropy. The advantages of the latter are:
- The method does not take overall image statistics for its correction but rather surface cover dependent parameters.
- distribution of the natural brightness in across track direction has no impact on the results (statistical normalization is prone to such variations)
- the results are reproducisble and consistent amongst image series and mosaics as the same correction factors are always used for the same ovservation angles and object types in BREFCOR whereas statistics may be different between adjacent flights.