Re: [GRASS-user] Processing LiDAR data in GRASS GIS
Hello Hamish and Mark, This way is a lot more easy! Probably it would take me a lot of time to find it myself :-) Thank you for the help and keep doing the good job for GRASS and the community! Greetings, Adrian Kirilov On Thu, May 2, 2013 at 11:57 PM, Hamish hamis...@yahoo.com wrote: Adrian wrote: I have LiDAR data in ASCII txt files with only X, Y and Z coordinates, which I want to import and create DEM models from in GRASS. I'm new to this kind of data processing. -- see http://grass.osgeo.org/wiki/LIDAR r.in.xyz + r.surf.nnbathy is my favorite combo for this, but then, I'm biased. 3.5M points should run in a few seconds. (r.surf.nnbathy from the wiki AddOns page) The choice between v.in.ascii and r.in.xyz really depends on if you want to do full analysis on the point cloud or just make a fast DEM from an already cleaned x,y,z set. 3.5M points is on the limit of the number of vector points you can work with in GRASS 6 with full topology and database tables unless you have a computer with lots of RAM. (thus options to disable first database creation and second topology) Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Processing LiDAR data in GRASS GIS
Le 2013-05-02 23:57, Hamish a écrit : 3.5M points is on the limit of the number of vector points you can work with in GRASS 6 with full topology and database tables unless you have a computer with lots of RAM. (thus options to disable first database creation and second topology) Hi Hamish, Then what would be the limit for grass7 with 4gb of ram, no topology/database ? Can it handle billions of points ? ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Processing LiDAR data in GRASS GIS
jr.morreale wrote: Then what would be the limit for grass7 with 4gb of ram, no topology/database ? Can it handle billions of points ? I don't really know to be honest. Try the experimental approach and keep an eye on `top`, and let us know the results. :) See the grass wiki FAQ for a hint on adding temporary swap space on Linux if you need it. r.in.xyz can handle many billions of points without trouble for non-exotic statistical aggregations; memory use there is more a matter of raster region size and you can do multi-pass if memory is an issue on a really really huge region. Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Processing LiDAR data in GRASS GIS
On 05/03/2013 01:18 PM, Hamish wrote:
jr.morreale wrote:
Then what would be the limit for grass7 with 4gb of ram, no
topology/database ? Can it handle billions of points ?
In my experience, it can (even GRASS 6), if:
a) you rasterize the input data directly (r.in.xyz,
as suggested by Hamish).
b) your file system supports files 4GB (which really
just about anything except a VFAT formatted USB drive
should these days)
and
c) (in case you want to export the results for use
with another GIS) your GDAL has a GeoTIFF driver
that has 64 bit BigTIFF support enabled.
To save storage space, use single precision
floating point data if you can.
Best,
Ben
I don't really know to be honest. Try the experimental approach
and keep an eye on `top`, and let us know the results. :) See the
grass wiki FAQ for a hint on adding temporary swap space on Linux
if you need it.
r.in.xyz can handle many billions of points without trouble for
non-exotic statistical aggregations; memory use there is more a
matter of raster region size and you can do multi-pass if memory
is an issue on a really really huge region.
Hamish
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--
Dr. Benjamin Ducke, M.A.
{*} Geospatial Consultant
{*} GIS Developer
bendu...@fastmail.fm
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Re: [GRASS-user] Processing LiDAR data in GRASS GIS
On Fri, May 3, 2013 at 1:18 PM, Hamish hamis...@yahoo.com wrote: jr.morreale wrote: Then what would be the limit for grass7 with 4gb of ram, no topology/database ? Can it handle billions of points ? Yes: http://grasswiki.osgeo.org/wiki/GRASS_GIS_Performance#Vector_geometry In all GRASS GIS versions, * with topology the feature limit is at time 2^31 - 1 (about 2 billion) features per vector map. But you can disable topology to be build when importing: v.in.ascii -b Do not build topology in points mode See for more details: http://grass.osgeo.org/grass70/manuals/v.in.ascii.html TODO: understand the limit when using the -b flag. Markus ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Processing LiDAR data in GRASS GIS
*Hello to all users of GRASS,* * * * I have LiDAR data in ASCII txt files with only X, Y and Z coordinates, which I want to import and create DEM models from in GRASS. I'm new to this kind of data processing.* * * * I'am using the following approach in a new MAPSET:* db.connect driver=sqlite database=$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite.db v.in.ascii input=b29_3.txt output=b29_3 fs=space z=3 g.region vect=b29_3 -p *# I tried few times at this point to interpolate the points with IDW using v.surf.idw. It stated that I have to show in which column of the attribute table are Z values in order to execute the command.* * At this point I don't have an attribute table yet created for the vector map b29_3...so I tried this one:* v.db.addtable map=b29_3@testMapset11 columns=cat integer, x double precision, y double precision, z double precision #* ...and after that:* v.to.db map=b29_3 option=coor columns=x, y, z * * *# for to populate the database with and finally use v.surf.idw* *Is it my approach correct because it takes too much time (I mean few hours for only one txt file with 3 500 000 points) and it's very slow...and I'm really not sure how to proceed? And if no what is the correct one? * * * * I tried also to create an attribute table even with v.in.ascii when still importing the data, but I don't have attributes and it doesn't create tables only for X, Y and Z coordinates (I don't know why).* * * * Any help will be highly appreciated! Thank you!* * * * * * Greetings,* * * * Adrian Kirilov* ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Processing LiDAR data in GRASS GIS
Hi, v.in.ascii input=b29_3.txt output=b29_3 fs=space z=3 You could skip the attribute table by using this command and make 3D points and not build topology: v.in.ascii -z -t -b input=text_file.xyz output=surface_points fs=space z=3 g.region vect=b29_3 -p The -a flag aligns the region. Was the resolution set prior? If the resolution was not set, you can do this with: g.region vect=b29_3 -ap res=your desired resolution It stated that I have to show in which column of the attribute table are Z values in order to execute the command. The v.surf.rst module produces very nice results and allows usage of the 3D points (-z). Mark ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
