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<DIV dir=ltr align=left><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><o:p></o:p></DIV>
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