[GRASS-user] How does GRASS do tiled processing?

[Milton Cezar Ribeiro]

Hi Jonathan,

When I need to do tiles processing of grass coupled R, I usually set a list
of bounding boxes on R (a list of x1, x2, y1, y2), and then I put it on a
for() looping. So, I set a new g.region using n= s= e= and w= parameters
using system() function of R (you can do it of other ways). Just after the
for() I reset g.region with -d.

*but* you need to be very careful with your processing, because some of the
results will be influenced by the boundary of new sub-regions.

Good luck

milton
brazil=toronto

2009/7/8 Jonathan Greenberg <greenberg at ucdavis.edu>

> GRASSers:
>
>   I was curious -- how is tiled processing realized in GRASS GIS?  Is there
> a fixed input tile size (in MB of RAM or # of lines)?  Is there some
> documentation buried on the GRASS site that describes the algorithm?  I'm
> trying to replicate an efficient tiled approach in R -- I was basing it off
> the ENVI approach (precalculate the input data memory footprint per line of
> data, read in as many lines as the memory cap allows, process, write those
> lines, rinse, repeat), but I was curious if GRASS had a different approach.
>
> --j
>
> --
>
> Jonathan A. Greenberg, PhD
> Postdoctoral Scholar
> Center for Spatial Technologies and Remote Sensing (CSTARS)
> University of California, Davis
> One Shields Avenue
> The Barn, Room 250N
> Davis, CA 95616
> Cell: 415-794-5043
> AIM: jgrn307, MSN: jgrn307 at hotmail.com, Gchat: jgrn307
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