[GRASS-user] Estimating Albedo from Landsat
ssefick at gmail.com
Mon Sep 13 07:57:29 EDT 2010
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
> 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
>>> 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
>> 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?
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