[GRASS-user] <i.landsat.trim> -- script to trim Landsat images, make footprints and all-coverage mask
amuriy at gmail.com
Thu Dec 20 23:58:34 PST 2012
2012/12/21 Nikos Alexandris <nik at nikosalexandris.net>
> I am testing <i.landsat.trim>. Nice work!
> how do we interpret exactly the "rast_buffer" parameter?
"rast_buffer" is the "service" parameter, which is used for several actions
with the input raster bands. First of all, it identifies the width of
raster buffer zone for making the band mask; also it controls the
resolution of region during processing. It was gained experimentally with
the best value near 300 meters for Landsat 7 images (sounds not very
logical, I understand).
> Testing on a single L5T band, I get strange (to me) results with various
> distances (e.g., 100, 150, 200, 5000, 10000). Where does the buffer
Does it start from the outer non-NULL pixels of the image for example?
Yes, the buffer start on the border of the band mask, but with the
significantly coarser region resolution. 10000
> Is it
> expected that some distance (e.g. 100) will result in an (almost) empty
Can be expected almost anything, that's why the module needs some work to
make it more logical and more usable. I already started rewriting it in
Python, along the way I'll try to complement it and fix some functions.
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