[GRASS-dev] big speedups for i.landsat.rgb

[Michael Barton]

On Jun 18, 2012, at 8:35 PM, Hamish wrote:

> Hamish wrote:
>> i.oif(.sh) is also low-hanging fruit, and we can also port the
>> method over to python scripts
> 
> Hi,
> 
> The r.univar part of i.oif is now parallelized in 6.5svn (.sh)
> and trunk (.py) versions.
> 
> .sh:  https://trac.osgeo.org/grass/changeset/52126
> .py:  https://trac.osgeo.org/grass/changeset/52128
> 
> 
> I'm guessing we can borrow some ideas from xargs/gnu parallel to
> make a new reusable python wrapper function to de-clutter the
> python method's implementation.
> 
> 
> i.landsat.rgb.py in trunk needs a more invasive change so I
> haven't touched that yet.
> 
> 
> Michael: would this work with for your new imagery module?
> (is that slow to run or very processor bound?)

Exactly what I was thinking. It requires processing 3 bands. Histogram equalization might also benefit. It runs pretty quickly on a few hundred K cells, but once you get up to the size of full landsats, it slows down.

Michael

> 
> 
> Hamish

_____________________
C. Michael Barton
Visiting Scientist, Integrated Science Program
National Center for Atmospheric Research &
University Consortium for Atmospheric Research
303-497-2889 (voice)

Director, Center for Social Dynamics & Complexity 
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University
www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu