[GRASS-user] Estimating Albedo from Landsat

[Nikos Alexandris]

Nikos:

> > Did you finally used i.landsat.toar for the Landsat5 - TM bands?

Hamish:
 
> I haven't tried with landsat 5 data from glovis yet, have some scenes
> on order, expect them to arrive in the next few days. It seems to be
> working for me with landsat7 data. Band 61 temperatures seem plausible
> anyway & metadata file is read cleanly.

And example of metadata (of the image I am using):
<http://edcsns17.cr.usgs.gov/cgi-
bin/EarthExplorer/phtml/results/display_full.phtml?cseq=3119&row=3&fgdc=N&entity_id=LT51830332007248MOR00>. 
I guess it's structure is quite different than the "meta" of ETM+ data.

> > 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.

> I am a bit suspicious of the if(flag->answer) bits of the code, if pointers
> and boolean integers are getting mixed up.

> I think over the next week or two I'll continue to make small cleanups and
> improvements to the i.landsat.toar and i.landsat.acca code.
 
> > 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?
 
> how much time? for me it takes a few minutes.

Oh man, I guess I am doing something wrong [ again :-( ]. It takes too much 
time here. I broke the process after >30 min and set up a new (smaller) 
computational region (of my interest). I'll give it another try and report 
back.

Thanks for all of your work Hamish, Nikos