[GRASS-user] Estimating Albedo from Landsat

[stephen sefick]

Those are digital numbers.

On Mon, Sep 13, 2010 at 6:38 AM, Daniel Victoria
<daniel.victoria at gmail.com> wrote:
> Hi Nikos,
>
> I did not use i.landsat.toar. I converted the DN values to radiance
> manually, using r.mapcalc and the formula and  coefficients provided.
>
> Are you going to use i.atcorr? I'm still trying to figure out which is
> the correct procedure for i.atcorr:
>
> 1) Convert DN to radiance and run i.atcorr (wiki example)
> 2)  Use DN values in i.atcorr (man page exemple)
>
> And also, what are the output units since they appear to be scaled from 1 to 255
>
> Cheers
> Daniel
>
> 2010/9/12 Nikos Alexandris <nikos.alexandris at felis.uni-freiburg.de>:
>> Daniel Victoria:
>>
>>> I haven't tryed i.landsat.toar addon but from what I read in the wiki
>>> (http://grass.osgeo.org/wiki/Atmospheric_correction) I could either
>>> use i.landsat.toar or a DN - Radiance conversion formula that is
>>> given...
>>
>>> Will try to recalculate the images, I might have done something wrong
>>
>> Hi Daniel!
>>
>> Did you finally used i.landsat.toar for the Landsat5 - TM bands?
>>
>> I am trying to use the module on the LT51830332007248MOR00 image(s) and have
>> several (expected) problems, like:
>>
>> (note that the metadata file I downloaded via GLOVis has a ".meta" extension)
>>
>> 1. the "LT51830332007248MOR00.meta" isn't read correctly or the module is
>> looking for a string other than the "date_acquired = 20070905" string which is
>> the only "date-string" included in the ".meta" file
>>
>> 2. does not recognize the solar elevation value
>>
>> (the above "cases" are mentioned in the manual, so manual feed is required
>> here)
>>
>> 3. after manually providing the "solar_elevation" and the "product_date" and
>> using the "-v" flag, some random (?) segfaults occur.
>>
>> 4. without the "-v" flag it runs but seems to take too much time? OK, the
>> image set is large ( 7654 cols x 7127 rows x 7 bands). --- Is it really taking
>> so long or is there something wrong?
>>
>> Nikos
>>
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>



-- 
Stephen Sefick
____________________________________
| Auburn University                                   |
| Department of Biological Sciences           |
| 331 Funchess Hall                                  |
| Auburn, Alabama                                   |
| 36849                                                    |
|___________________________________|
| sas0025 at auburn.edu                             |
| http://www.auburn.edu/~sas0025             |
|___________________________________|

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

                                -K. Mullis

"A big computer, a complex algorithm and a long time does not equal science."

                              -Robert Gentleman