I am getting very low reflectance values (mostly < 0.15) in all bands of multiple Landsat 7 scenes after having converted to TOA reflectance manually in ENVI. These values are not supposed to happened. The objective is to perform relative radiometric normalization between these scenes (2010) and others from Landsat 8 (2016) (OLI scenes worked well!).

  • You should provide examples of formulas and calculations, in order to give us something to validate. As it stand, we can't check where the problems comes from. – Mikkel Lydholm Rasmussen Mar 31 '17 at 15:33
  • @MikkelLydholmRasmussen I have tried multiple ways. First, I converted into radiance using Radiance_Mult * B+Radiance_Add (I also tried the other equation: ((Radiance_Maximum-Radiance_Minimum)/(255-1))*(B-1)+Radiance_Minimum). Then, I converted each radiance band into reflectance as: Reflectance_Mult * B_rad+Reflectance_Add/sin(Sun_Elevation * π/180). Once again, I tried other equation in this step: π * B_rad * Earth Sun Distance^2/ETM+ Solar Spectral Irradiance*cos((90-Sun_Elevation)*π/180). Finally, I have converted directly into Reflectance (which I suppposed it isn't correct in Landsat 7). – Ana Leite Apr 3 '17 at 14:30

I suggest you use the Landsat surface reflectance product from USGS (some information here). While there are differences in how surface reflectance is calculated for each dataset, it is at least a fairly reasonable attempt at estimating the same magnitude.

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