[GRASS-user] Simultaneous r.horizon processes
Collin Bode
collin at berkeley.edu
Tue Apr 17 15:21:33 EDT 2012
Lee,
I tried the same thing, trying to integrate a full workflow in Python for r.sun (see attached code). I am using a 2x2 meter lidar elevation map with about 120 million cells, so automation is pretty necessary. The whole thing takes 3 weeks to run using 8 CPU cores and 12GB ram.
However, r.horizon does not work properly on Grass 6.4.2. I can only get it to run on one core in sequence. I cannot get it to accept a single angle and run properly. The output is always for angle 0, both in name and output data. Bug? I was planning to post this to the dev list if no one responds here.
It would be worthwhile to find out if your version is simply overwriting the previous, similarly named map. If it is, and the maps are actually different (r.info), then you can change your code to run r.horizon for a single angle, then rename the map. Something like this:
for azimuth in range(0,361,step_size):
grass.run_command("r.horizon", elevin=dem, \
direction=angle, maxdistance=maxdistance, \
horizon=prefhor, dist=dist, overwrite = 1)
az = str(azimuth).zfill(3)
tempmap = prefhor+'_0'
horizonmap = prefhor+'_'+az
cmd = tempmap+","+horizonmap
grass.run_command("g.rename",rast=cmd)
r.sun does work in multiple cores.
Collin Bode
Project Manager, Desktop Watershed Integrated Program
National Center for Earth-surface Dynamics
University of California, Berkeley
http://www.nced.umn.edu
http://ib.berkeley.edu/labs/power
http://angelo.berkeley.edu
On Apr 1, 2012, at 5:10 AM, Daniel Lee wrote:
> Hi list,
>
> I've got a large area I'm running r.horizon on. Since the process takes quite a while but it only runs on one processor core and I've got plenty of RAM, I've decided to script it in Python and use run_command and start_command in order to create multiple horizon maps in parallel. Another reason I'm doing it that way is that I only need certain horizons, so I don't want GRASS to do all 360°.
>
> The problem is, when I run the script, all of the maps that I want made seem to be made and I can see in top that there are several instances of r.horizon. But only the instance to be finished last is actually saved. Here's the output:
>
> Calculating map 1 of 1 (angle 0.000000, raster map <horizon0_0>)
> 100%
> Calculating map 1 of 1 (angle 12.500000, raster map <horizon12.5_0>)
> Calculating map 1 of 1 (angle 7.500000, raster map <horizon7.5_0>)
> Calculating map 1 of 1 (angle 42.500000, raster map <horizon42.5_0>)
> Calculating map 1 of 1 (angle 150.000000, raster map <horizon150.0_0>)
> 100%
> Calculating map 1 of 1 (angle 162.500000, raster map <horizon162.5_0>)
> 100%
> Calculating map 1 of 1 (angle 175.000000, raster map <horizon175.0_0>)
> Calculating map 1 of 1 (angle 167.500000, raster map <horizon167.5_0>)
> Calculating map 1 of 1 (angle 197.500000, raster map <horizon197.5_0>)
> Calculating map 1 of 1 (angle 205.000000, raster map <horizon205.0_0>)
> Calculating map 1 of 1 (angle 225.000000, raster map <horizon225.0_0>)
> 100%
> Calculating map 1 of 1 (angle 257.500000, raster map <horizon257.5_0>)
> Calculating map 1 of 1 (angle 262.500000, raster map <horizon262.5_0>)
> 100%
> Calculating map 1 of 1 (angle 275.000000, raster map <horizon275.0_0>)
> 100%
> Calculating map 1 of 1 (angle 295.000000, raster map <horizon295.0_0>)
> Calculating map 1 of 1 (angle 300.000000, raster map <horizon300.0_0>)
> 100%
> Calculating map 1 of 1 (angle 322.500000, raster map <horizon322.5_0>)
> Calculating map 1 of 1 (angle 325.000000, raster map <horizon325.0_0>)
> 100%
> Calculating map 1 of 1 (angle 337.500000, raster map <horizon337.5_0>)
> Calculating map 1 of 1 (angle 335.000000, raster map <horizon335.0_0>)
> Calculating map 1 of 1 (angle 345.000000, raster map <horizon345.0_0>)
> Calculating map 1 of 1 (angle 350.000000, raster map <horizon350.0_0>)
> 100%
> Calculating map 1 of 1 (angle 352.500000, raster map <horizon352.5_0>)
> 100%
> Calculating map 1 of 1 (angle 355.000000, raster map <horizon355.0_0>)
> 100%
> Calculating map 1 of 1 (angle 357.500000, raster map <horizon357.5_0>)
> 100%
> Calculating map 1 of 1 (angle 257.500000, raster map <horizon257.5_0>)
> Calculating map 1 of 1 (angle 262.500000, raster map <horizon262.5_0>)
> 100%
> Calculating map 1 of 1 (angle 275.000000, raster map <horizon275.0_0>)
> 100%
> Calculating map 1 of 1 (angle 295.000000, raster map <horizon295.0_0>)
> Calculating map 1 of 1 (angle 300.000000, raster map <horizon300.0_0>)
> 100%
> Calculating map 1 of 1 (angle 322.500000, raster map <horizon322.5_0>)
> Calculating map 1 of 1 (angle 325.000000, raster map <horizon325.0_0>)
> 100%
> Calculating map 1 of 1 (angle 337.500000, raster map <horizon337.5_0>)
> Calculating map 1 of 1 (angle 335.000000, raster map <horizon335.0_0>)
> Calculating map 1 of 1 (angle 345.000000, raster map <horizon345.0_0>)
> Calculating map 1 of 1 (angle 350.000000, raster map <horizon350.0_0>)
> 100%
> Calculating map 1 of 1 (angle 352.500000, raster map <horizon352.5_0>)
> 100%
> Calculating map 1 of 1 (angle 355.000000, raster map <horizon355.0_0>)
> 100%
> Calculating map 1 of 1 (angle 357.500000, raster map <horizon357.5_0>)
> 100%
>
> But when I do g.list rast at the end of it all I only have these maps:
> raster files available in mapset <Cloppenburg>:
> dom_aspect horizon162.5_0 horizon325.0_0
> dom_complete horizon225.0_0 horizon350.0_0
> dom_slope horizon262.5_0 horizon352.5_0
> horizon0_0 horizon275.0_0 horizon355.0_0
> horizon150.0_0 horizon300.0_0 horizon357.5_0
>
> As you can see, the only horizon maps saved are the last ones made. Does anybody know why this is the case and, if so, what would be a good workaround? Finding the horizons serially on only one processor means that my computer does a lot of sitting around twiddling thumbs. Thanks a bunch!
>
> Daniel
> --
>
> B.Sc. Daniel Lee
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