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bio website nikosalexandris.net/xpress/en
location Greece
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visits member for 2 years, 11 months
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Dec
8
comment Pan sharpen Landsat 8 using Grass 7
Please, post full commands to make clear, for example, on which maps the statistics refer to. Also, for the sharpening part, you can give a try of this one: i.fusion.hpf (works for GRASS GIS ver. 7.x).
Dec
8
comment Create a rectangular buffer from point shapefile using QGIS/GRASS/SAGA GIS/R
You are trying to create a grid of size 16x22 km^2, where each point is the centroid of a cell, right? The cells are the ones that build up the grid. Is that so?
Dec
4
awarded  Revival
Dec
3
comment repeating steps in GRASS r.mapcalc
The loop in one line: for I in `seq $X`; do r.mapcalc "new = old + 10" --overwrite && g.rename rast=new,old --overwrite; done ;-)
Nov
29
revised 6s parameters used in grass gis
Some formatting
Nov
29
revised image size has been increased after i.atcorr
Some formatting
Nov
29
revised How to determine aerosol model value for i.atcorr in GRASS?
Pretty link
Nov
29
revised how can i correct atmospherically landsat 8 images?
Some formatting
Nov
29
suggested approved edit on 6s parameters used in grass gis
Nov
29
comment 6s parameters used in grass gis
If you are after so many details, maybe you should check Py6S - A Python interface to 6S.
Nov
29
revised how can i correct atmospherically landsat 8 images?
added 295 characters in body
Nov
29
suggested approved edit on how can i correct atmospherically landsat 8 images?
Nov
29
answered how can i correct atmospherically landsat 8 images?
Nov
29
comment How to determine aerosol model value for i.atcorr in GRASS?
Two more, potentially useful, links: globaerosol.info/project_description/data.htm, gacp.giss.nasa.gov/data_sets
Nov
29
suggested approved edit on How to determine aerosol model value for i.atcorr in GRASS?
Nov
29
comment Trouble with opening/using i.atcorr in GRASS
In any case, @Willy's comment/question is valid. That is, frequently, it's not necessary to apply sophisticated algorithms to compensate for atmospheric effects. Unless the image is heavily influenced, and there is no other way to try to make it usable data.
Nov
29
comment Trouble with opening/using i.atcorr in GRASS
You might want to test a custom work-in-progress python script to loop i.atcorr over all bands that pertain to a Landsat scene (should work for Landsat5 TM as well): i.landsat.atcorr.
Nov
29
comment GRASS i.atcorr outputs unusual values
It is not uncommon to have higher than 1 spectral reflectance values. Some explorations and explanations here: surfaceheat.sites.yale.edu/sites/default/files/…
Nov
29
comment image size has been increased after i.atcorr
First, did you check the extent of the computational region? Second, what is 4 times (bigger, I guess) than which input image? An image (a Landsat band in this case) stored in GRASS' data base? Which data types are fine?
Nov
29
suggested approved edit on image size has been increased after i.atcorr