I sent a previous mail but it did not go through, so sending it again:
The base concept is that if we are going to parallelize, then the
parallelization can be of two types,
keeping the current algorithm and tweaking it to become more parallel.
Here, a method will be to run the r.cost of two
On Sat, Apr 11, 2009 at 10:23 PM, Jyothish Soman
jyothish.so...@gmail.com wrote:
...
The assumption I am making is that the algorithm for r.cost is closely
related to dijkstra's algorithm.
Just a note:
in GRASS-Addons is a new module (r.terracost which uses this approach):
Well actually, the paper is in GIS terms what has been given in my reference
in graph theoretical terms.
Can somebody tell me how exactly are r.cost and r.terraflow different, in
terms of cost of traversal between two pixels?
On Sun, Apr 12, 2009 at 2:10 AM, Markus Neteler nete...@osgeo.org
Colin Nielsen wrote:
In my experience, the main drain in computation time is the IO not the
actual calculation of the btree. Is there any way to parallelize the
IO by passing rows to different cores or something like that ie. for
(row = 0; row nrows; row++) {?
That's feasible, but r.cost
In my experience, the main drain in computation time is the IO not the
actual calculation of the btree. Is there any way to parallelize the
IO by passing rows to different cores or something like that ie. for
(row = 0; row nrows; row++) {?
Or a more efficient segment library sounds good as well.
Colin wrote:
A colleague of mine would like to run a cost analysis
(with either r.walk or r.cost) on a very very large
raster, ~ 1500 km x 800 km with about 30 m resolution
equals about 40 billion cells.
[ see my other today's email about r.terracost now in
Addons ]
Is there any
Colin Nielsen wrote:
A colleague of mine would like to run a cost analysis (with either
r.walk or r.cost) on a very very large raster, ~ 1500 km x 800 km with
about 30 m resolution equals about 40 billion cells. This is obviously
going to take a ridiculously long time, and he would like to
A colleague of mine would like to run a cost analysis (with either
r.walk or r.cost) on a very very large raster, ~ 1500 km x 800 km with
about 30 m resolution equals about 40 billion cells. This is obviously
going to take a ridiculously long time, and he would like to make use
of his dual
