[GRASS-dev] Week 11: GRASS GIS 3D flowlines

Anna Petrášová kratochanna at gmail.com
Wed Aug 6 19:58:05 PDT 2014


On Tue, Aug 5, 2014 at 11:04 AM, Newcomb, Doug <doug_newcomb at fws.gov> wrote:

> Anna,
> Will you post the  benchmarking results  for the OpenMP computation vs the
> non-OpenMP?
after some testing, my conclusion is that OpenMP does not really speed up
gradient computation and it can even slow it down. I tried it on my laptop
with 2 cores and on a powerful computer with 12 cores, with different sizes
of processed blocks and I didn't get any significant speed-up. The most
costly seems to be writing of the three 3D rasters and the gradient
computation is relatively short. I also tested different cache settings but
default settings seems to be optimal, I got only similar or worse results
with different cache settings.  I hope I didn't missed anything, since this
is quite new to me.



> On Fri, Aug 1, 2014 at 3:54 PM, Anna Petrášová <kratochanna at gmail.com>
> wrote:
>> Hi,
>> 1. What did you get done this week:
>> I implemented adding attributes to each segment of a flowline. I added
>> column with velocities and values of input 3D raster along the flowline.
>> The result can be visualized by using vector color tables (v.colors) in 2D
>> and 3D.
>> I started writing r3.gradient module based on the gradient function in
>> r3.flow. The module is already running and giving correct results, I will
>> add it to addons once the gradient function is moved to library.
>> 2. What do you plan on doing next week?
>> I will try to parallelize the gradient computation with openMP, the
>> structure of the code is already prepared for that. Then, I plan to add
>> more tests.
>> 3. Are you blocked on anything?
>> No.
>> Anna
>> [1]
>> http://trac.osgeo.org/grass/wiki/GSoC/2014/ImplementationOf3DRasterFlowLine
>> [2]
>> http://trac.osgeo.org/grass/browser/grass-addons/grass7/raster3d/r3.flow
>> _______________________________________________
>> grass-dev mailing list
>> grass-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/grass-dev
> --
> Doug Newcomb
> Raleigh, NC
> 919-856-4520 ext. 14 doug_newcomb at fws.gov
> ---------------------------------------------------------------------------------------------------------
> The opinions I express are my own and are not representative of the
> official policy of the U.S.Fish and Wildlife Service or Dept. of the
> Interior.   Life is too short for undocumented, proprietary data formats.
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