[GRASS-user] Importing USGS' wrs2_descending Shapefile

[Moritz Lennert]

On 06/03/15 08:44, Nikos Alexandris wrote:
> ..
>
>>> Markus M:
>
>>> So, I guess I'll forget the idea to fully automatise the process of
>>> Landsat
>>> border trimming? Can't we just have all of the Path-Row tiles ready
>>> in a
>>> compressed GRASS format? Some sort of packed ASCII file which can be
>>> easily
>>> imported?  No other ideas?
>>
>> I think you can trim the borders using the Landsat raster data
>> themselves: according to the metadata, valid numbers are > 0. If the
>> sum of all bands is zero, the pixel is outside.

If valid numbers > 0, why does the sum of all bands have to be zero ? 
Normally, all bands are aligned, so in my understanding any 0 can be set 
to NULL, or ?

Moritz