<br><div class="gmail_quote">On Mon, Jan 3, 2011 at 4:01 PM, <span dir="ltr"><<a href="mailto:Doug_Newcomb@fws.gov">Doug_Newcomb@fws.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br><font face="sans-serif" size="2">Markus M.,</font>
<br><div class="im">
<br><tt><font size="2">>Large file support does not help here because
8.5 billion points<br>
>exceeds the number of supported features in GRASS vectors which is<br>
>about 2 billion (2,147,483,647 to be precise).</font></tt>
<br></div><tt><font size="2"> I'll chop the
inputfile into sections less than 2 billion then. Is there any reason that
the 2 billion limit on GRASS vectors cannot be raised? ( variable change
vs types of variable and lots of ugly fixes in various places?) If it's
something simple, I can play with it, but I'm not a C programmer :-(. </font></tt>
<br><div class="im"><tt><font size="2"><br></font></tt></div></blockquote><div>The limit can be raised, but, unfortunately, this is not simple, because portability across platforms must be maintained. It boils down to the problem that it is not simple to have a portable 64 bit integer type on at least Linux, Mac, Windows, both 32 bit and 64 bit architectures. I would like to have a portable 64 bit integer type for grass 7 though...<br>
<br>Markus M<br><br></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div class="im"><tt><font size="2">
<br>
>Further on, a region with 6.8 billion cells is a bit large since the<br>
>interpolated raster will be held in memory which would require about<br>
>50 GB RAM (that could be fixed for v.surf.bspline by keeping</font></tt>
<br><tt><font size="2">>intermediate data on disk).</font></tt>
<br></div><tt><font size="2"> I know some folks with computers with 64GB+
of RAM, so that is not an insurmountable issue. However, it would probably
be better to go the intermediate route. </font></tt>
<br><div class="im"><tt><font size="2"><br>
> No idea where the request for<br>
>18446744071812941729 * 8 bytes comes from, this is astronomical.</font></tt>
<br></div><tt><font size="2">That was my reaction. Perhaps the computer was
screaming in pain.:-)<div class="im"><br>
<br>
>Apart from that, spline steps of 40 seem ok, since the point distance<br>
>is 5 m or less, spline steps of 20 would also be ok. The larger the<br>
>spline steps, the smoother the resulting surface. Smoothing is also<br>
>controlled through lambda.<br>
</div></font></tt>
<br><tt><font size="2">Thanks for the insight, I will need to change my approach
to minimize the smoothing.</font></tt>
<br>
<br><tt><font size="2">Doug</font></tt>
<br>
<br>
<br>
<br><tt><font size="2"><br>
Markus M</font></tt>
<br><div class="im"><font face="sans-serif" size="2">Doug Newcomb
<br>
USFWS<br>
Raleigh, NC<br>
919-856-4520 ext. 14 <a href="mailto:doug_newcomb@fws.gov" target="_blank">doug_newcomb@fws.gov</a><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>
<br>
<br>
<br>
</div><table width="100%">
<tbody><tr valign="top">
<td width="40%"><font face="sans-serif" size="1"><b>Markus Metz <<a href="mailto:markus.metz.giswork@googlemail.com" target="_blank">markus.metz.giswork@googlemail.com</a>></b>
</font>
<p><font face="sans-serif" size="1">01/03/2011 09:13 AM</font>
</p></td><td width="59%">
<table width="100%">
<tbody><tr valign="top">
<td>
<div align="right"><font face="sans-serif" size="1">To</font></div>
</td><td><div class="im"><font face="sans-serif" size="1">Markus Neteler <<a href="mailto:neteler@osgeo.org" target="_blank">neteler@osgeo.org</a>></font>
</div></td></tr><tr valign="top">
<td>
<div align="right"><font face="sans-serif" size="1">cc</font></div>
</td><td><font face="sans-serif" size="1"><a href="mailto:Doug_Newcomb@fws.gov" target="_blank">Doug_Newcomb@fws.gov</a>, <a href="mailto:grass-dev@lists.osgeo.org" target="_blank">grass-dev@lists.osgeo.org</a></font>
</td></tr><tr valign="top">
<td>
<div align="right"><font face="sans-serif" size="1">Subject</font></div>
</td><td><font face="sans-serif" size="1">Re: [GRASS-dev] How many points in a
point layer and v.surf.bspline questions</font></td></tr></tbody></table>
<br>
<table>
<tbody><tr valign="top">
<td>
</td><td></td></tr></tbody></table>
<br></td></tr></tbody></table><div><div></div><div class="h5">
<br>
<br>
<br><tt><font size="2">On Mon, Jan 3, 2011 at 2:57 PM, Markus Neteler <<a href="mailto:neteler@osgeo.org" target="_blank">neteler@osgeo.org</a>>
wrote:<br>
> hi Doug,<br>
><br>
> On Mon, Jan 3, 2011 at 2:26 PM, <<a href="mailto:Doug_Newcomb@fws.gov" target="_blank">Doug_Newcomb@fws.gov</a>>
wrote:<br>
>><br>
>> Hi Folks,<br>
>><br>
>> I aggregated all of the bare earth lidar points for the state
of North<br>
>> Carolina into a single file Imported all 8.5 billion points
for NC into one<br>
>> point layer with no topology. I was sort of curious to see
if I could<br>
>> generate a seamless 20 ft elevation grid for the State of North
Carolina<br>
>> from a single data layerusing bspline and tried the following
command:<br>
>><br>
>> GRASS 6.5.svn (ncstpft_nad83):~ > v.surf.bspline input=all_nc_be_pts2<br>
>> raster=all_nc_be_20ft_bspline sie=40 sin=40 layer=0<br>
>> WARNING: Coor files of vector map <all_nc_be_pts2@statewide>
is larger than<br>
>> it should be
(158913789952 bytes excess)<br>
>> Cells for raster map <all_nc_be_20ft_bspline> will be interpolated<br>
>> ERROR: G_calloc: unable to allocate 18446744071812941729 * 8 bytes
of<br>
>> memory at dalloc.c:66<br>
><br>
> you are hitting the limits :) I dunno if large file support helps,
but<br>
> for vector data<br>
> it is only available in GRASS 7 to my knowledge.<br>
><br>
Large file support does not help here because 8.5 billion points<br>
exceeds the number of supported features in GRASS vectors which is<br>
about 2 billion (2,147,483,647 to be precise).<br>
<br>
Further on, a region with 6.8 billion cells is a bit large since the<br>
interpolated raster will be held in memory which would require about<br>
50 GB RAM (that could be fixed for v.surf.bspline by keeping<br>
intermediate data on disk). No idea where the request for<br>
18446744071812941729 * 8 bytes comes from, this is astronomical.<br>
<br>
Apart from that, spline steps of 40 seem ok, since the point distance<br>
is 5 m or less, spline steps of 20 would also be ok. The larger the<br>
spline steps, the smoother the resulting surface. Smoothing is also<br>
controlled through lambda.<br>
<br>
Markus M<br>
</font></tt>
<br></div></div></blockquote></div><br>