[GRASS-user] i.landsat.toar comments have only 0 value

[Daniel Victoria]

Niko,

Attached goes a screenshot showing my Grass version (6.4.3) and the
correction methods available in i.landsat.toar
Noticed the "corrected" method option.

Also, you can see in the GIS Layer Manager the output of r.info of one
of the reflectance images. Notice how all values are equal to zero...

This is what the manual says about the "corrected" method:
----
Corrected at-sensor values (method=corrected)
At-sensor reflectance values range from zero to one, whereas at-sensor
radiance must be greater or equal to zero. However, since Lmin can be
a negative number then the at-sensor values can also be negative. To
avoid these possible negative values and set the minimum possible
values at-sensor to zero, this method corrects the radiance to output
a corrected at-sensor values using the equations (not for thermal
bands):

radiance = (uncorrected_radiance - Lmin)

reflectance = radiance / sun_radiance
Note: Other possibility to avoid negative values is set to zero this
values (radiance and/or reflectance), but this option is ease with
uncorrected method and r.mapcalc.
-----

Cheers
Daniel

On Fri, Oct 18, 2013 at 5:35 AM, Nikos Alexandris
<nik at nikosalexandris.net> wrote:
> Daniel Victoria wrote:
>
>> Updating my last email. I also see the same problem in WinGrass 6.4.3
>>
>> And on a similar topic, i.landsat.toar in Grass6 has one extra
>> correction method when compared with Grass7.
>> In grass6 there is a Corrected at-sensor values options which I don't
>> see in Grass7. Why is that?
>
> Daniel, I only see the same for both versions:
>
> "Options: uncorrected,dos1,dos2,dos2b,dos3,dos4"
>
> Can you post more details?
>
> Nikos
>
> [rest deleted]
>
>
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