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<td width=40%><font size=1 face="sans-serif"><b>Markus Metz <markus.metz.giswork@googlemail.com></b>
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<p><font size=1 face="sans-serif">08/15/2011 06:28 AM</font>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif">Doug_Newcomb@fws.gov</font>
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<td><font size=1 face="sans-serif">grass-dev@lists.osgeo.org</font>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: [GRASS-dev] R.terraflow on massive
grids</font></table>
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<br><tt><font size=2>><Doug_Newcomb@fws.gov> wrote:<br>
>><br>
>> Hi Folks,<br>
>> I have an fcell grid of elevations for the state of North Carolina
(51000<br>
>> rows 133000 columns 6783000000 cells) . I tried to run r.terraflow
in<br>
>> GRASS7 ( 8/8/2011 svn snapshot) and ran into the dimension limits.
So I<br>
>> patched them according to Glynn's email ,<br>
>> </font></tt><a href="http://www.osgeo.org/pipermail/grass-user/2004-February/024722.html"><tt><font size=2>http://www.osgeo.org/pipermail/grass-user/2004-February/024722.html
and<br>
>> tried again ( Would it be better to change the dimension
variable to int<br>
>> instead of short int?) .<br>
>><br>
>> This time my Streams file builds to about 26 GB and then r.terraflow
bombs<br>
>> with :<br>
>><br>
>> MFD flow direction<br>
>> D8CUT=999999986991104.000000<br>
>> Memory size: 808.00M (847249408) bytes<br>
>> Memory manager registering memory in MM_IGNORE_MEMORY_EXCEEDED
mode.<br>
>> r.terraflow: grass2str.h:145: AMI_STREAM<T>*<br>
>> cell2stream(char*, elevation_type, long int*) [with T =<br>
>> float, elevation_type = float]: Assertion `nrows * ncols ==<br>
>> str->stream_len()' failed.<br>
>><br>
>> The memory size is interesting, because I'm giving it 8GB of RAM
out of 16<br>
>> GB in the command.<br>
<br>
>Note that the memory manager of the iostream lib used by r.terraflow<br>
>can only handle up to 2047 MB of RAM because the memory option in MB<br>
>is internally converted to Byte and stored as int, thus the max<br>
>recognized value is 2^31 - 1 Byte.<br>
<br>
>Markus M</font></tt></a>
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<br><tt><font size=2>This appears to be kind of like pulling on a corner
of a spiderweb. :-) </font></tt>
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<br><tt><font size=2>Should the limit to memory be indicated in the gui?</font></tt>
<br><tt><font size=2>Would there be any benefit to other parts of GRASS
in bumping up this memory limit? I can see the reason on 32 bit windows
XP, but that is starting to go away.</font></tt>
<br>
<br><tt><font size=2>Doug<br>
</font></tt>
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<br><font size=2 face="sans-serif">Doug Newcomb
<br>
USFWS<br>
Raleigh, NC<br>
919-856-4520 ext. 14 doug_newcomb@fws.gov<br>
---------------------------------------------------------------------------------------------------------<br>
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.</font>