[GRASS-user] i.atcorr output

GRASS GRASS user
1

Hi all,

This is problably a dumb question but, as someone posted the other day
"The only stupid question is the one not asked", here goes.

I'm using i.atcorr to correct landsat tm5 images and from the manual I
saw that the output is in reflectance. But it's scaled from 0 to 255.
The question is: The 255 value means a reflectance of 1? Or is 100 the
reflectance of 1?

Thanks
Daniel

2

Daniel Victoria wrote:

Hi all,

This is problably a dumb question but, as someone posted the other day
"The only stupid question is the one not asked", here goes.

I'm using i.atcorr to correct landsat tm5 images and from the manual I
saw that the output is in reflectance. But it's scaled from 0 to 255.
The question is: The 255 value means a reflectance of 1? Or is 100 the
reflectance of 1?

Thanks
Daniel
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I also have the same question about the scale. Why the output value from 0-255 not 0-1? I checked my data, it is not true that value of 255 is reflectance of 1. Please anybody help us how to get the true reflectance value or how to convert?
Best
Thy

3

Hi,

I had the same problem.
I don't know where your input data come from.
Now I know that it works if you use i.landsat.toar to calculate TOA
reflectance from DN images and then use these data as input files in
i.atcorr: you have also to use the flags -r (because of reflectance input)
and -f (because you need floating output).
I hope it will work!

Elena

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