[GRASS-user] Low reflectance values with i.atcorr and Landsat 8

[John, Lisa]

Hi,

I am using i.landsat.toar and i.atcorr –r for a region in Germany. The problem I face is that the resulting reflectance values are very low (0.2-0.3 for vegetation in band 5). I think the values should be higher (around 0.6).
I am using Landsat 8 images from Ocotber and from August. For both months I get that low values.
For i.atcorr –r I used an input range of 0,1 and an output range of 0,1. Any idea what I am doing wrong?
Overall the shapes of the reflectance curves for vegetation (value vs bands) seem reasonable, I am just worried about the values which seem to be too low.

i.landsat.toar input="LC81960252013275LGN00_B" output="10_toar_B" me\   |
 |    tfile="C:\Users\lj\Documents\grassdata\LC81960252013275LGN00_MTL.txt\   |
 |    " sensor="oli8" method="uncorrected" percent=0.01 pixel=1000 rayleig\   |
 |    h=0.0 scale=1.0

i.atcorr -r input="10_toar_B5 at l" range=0,1 parameters="C:\Users\lj\D\   |
 |    ocuments\grassdata\AC\6S parameters\10_i.atcorr_B5.txt" output="10_a\   |
 |    tcorr_B5" rescale=0,1

Regards, Lisa.
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