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List: osgeo-discuss
Subject: [OSGeo-Discuss] increase efficiency of analysis with r.grow.distance aka Euclidean allocation
From: "karsten" <karsten () terragis ! net>
Date: 2021-01-29 1:27:44
Message-ID: 557449C0669844979A69C5B26D162B43 () terragispc
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Hi All,
I am working on a project that requires to find the middle boundary between
raster regions (of the same value) using a maximum buffer distance. The
raster input I am using is quite large like 5m resolution and 100000 by
100000 cells. One approach I took was to fill all cells in areas outside the
raster regions in question which I will need to buffer to NULL
and then using the r.grow.distance in GRASS (similar to the Tool Euclidean
allocation in ArcGIS).
This works with smaller files but with a big input like the one above
calculation time is very long or might crash even on a fast PC. The only
remedy I found (apart from throwing larger RAM or hardware at the task)
so far was cutting up the raster file in tiles and running the analysis on
each tile and putting the results back afterwards to get to final result
layer.
Would anyone have hints if there are other approaches that I could increase
the efficiency of this analysis in GRASS or have any knowledge of other tool
sets such as R or python scripts that are already available for something
like this ?
Cheers
Karsten
Karsten Vennemann
<http://www.terragis.net> www.terragis.net
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<DIV><FONT color=#000080 size=2 face=Arial><SPAN class=896531501-29012021>Hi
All,</SPAN></FONT></DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN
class=896531501-29012021></SPAN></FONT> </DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN class=896531501-29012021>I am
working on a project that requires to find the middle boundary
between raster regions (of the same value) using a maximum buffer
distance. The raster input I am using is quite large like 5m resolution and
100000 by 100000 cells. One approach I took was to fill all cells in areas
outside the raster regions in question which I will need to buffer to NULL
<BR>and then using the r.grow.distance in GRASS (similar to the Tool
Euclidean allocation in ArcGIS). <BR></SPAN></FONT></DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN class=896531501-29012021>This
works with smaller files but with a big input like the one above calculation
time is very long or might crash even on a fast PC. The only remedy I found
(apart from throwing larger RAM or hardware at the task) <BR>so far was cutting
up the raster file in tiles and running the analysis on each tile and
putting the results back afterwards to get to final result
layer.</SPAN></FONT></DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN
class=896531501-29012021></SPAN></FONT> </DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN class=896531501-29012021>Would
anyone have hints if there are other approaches that I could increase the
efficiency of this analysis in GRASS or have any knowledge of other tool sets
such as R or python scripts that are already available for something like this
?</SPAN></FONT></DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN
class=896531501-29012021></SPAN></FONT> </DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN
class=896531501-29012021>Cheers</SPAN></FONT></DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN
class=896531501-29012021>Karsten</SPAN></FONT></DIV>
<DIV><FONT color=#000080 size=2 face=Arial><SPAN
class=896531501-29012021></SPAN></FONT> </DIV>
<DIV align=left>
<DIV><SPAN style="FONT-SIZE: 11pt; FONT-FAMILY: 'Verdana','sans-serif'">Karsten
Vennemann<BR></SPAN><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: 'Verdana','sans-serif'"><SPAN
style="COLOR: #003264"><A
title="http://www.terragis.net/ blocked::http://www.terragis.net/"
href="http://www.terragis.net"><FONT title=http://www.terragis.net/
color=#0000ff>www.terragis.net</FONT></A></SPAN></SPAN><?xml:namespace prefix =
"o" ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></DIV>
<DIV align=left><FONT color=#000080 size=2
face=Arial></FONT> </DIV></DIV></BODY></HTML>
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