[GRASS-user] Simultaneous r.horizon processes

[Daniel Lee]

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
Geschäftsführung für Forschung und Entwicklung
ISIS - International Solar Information Solutions GbR
Vertreten durch: Daniel Lee, Nepomuk Reinhard und Nils Räder

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35037 Marburg
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E-Mail: Lee at isi-solutions.org
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Bundesministerium für Wirtschaft und Technologie aufgrund eines Beschlusses
des Deutschen Bundestages, sowie durch die Europäische Union,
Zuwendungsgeber: Europäischer Sozialfonds.
Zusätzliche Unterstützung erhält ISIS von dem Entrepreneurship Cluster
Mittelhessen, der Universität Marburg, dem Laboratory for Climatology and
Remote Sensing und dem GIS-Lab Marburg.
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