[Liblas-devel] Re: Liblas-devel Digest, Vol 39, Issue 2
Aaron Reyna
aaron.reyna at gmail.com
Fri Mar 4 11:58:23 EST 2011
*It would be much, much, much faster if someone wrote some glue between
libLAS and GRASS (proposed here quite a while ago, but still not done <
http://lists.osgeo.org/pipermail/grass-dev/2008-May/037687.html>). I would
guess it would be an order of magnitude faster to ingest data if you didn't
have to go through text formats to do it.
And, for this LiDAR idiot. What is ground modeling?
Thanks,
Howard*
Ground Modeling is the process of taking the raw, ungrounded, recently
calibrated LiDAR files, and applying a grounding algorithm that pulls
default points into the ground class. The point is to separate the main two
classes (1 Default, and 2 Ground) from each other, while limiting vegetation
in the ground class that would normally appear in the DSM as opposed to the
DEM (if they were to be created from the .las files).
It's a little bit farther up the chain, but lends itself to pertinent in
that any processed LiDAR file can be reverted back to "grounded" by setting
all points back to default and applying another ground model suitable to the
individuals preference.
Aaron
All
On Fri, Mar 4, 2011 at 7:07 AM, <liblas-devel-request at lists.osgeo.org>wrote:
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> Today's Topics:
>
> 1. Re: Ground Modeling with RAW LiDAR and libLAS (Stuart Edwards)
> 2. Re: Ground Modeling with RAW LiDAR and libLAS (francesco)
> 3. Re: Ground Modeling with RAW LiDAR and libLAS (Howard Butler)
> 4. Re: Ground Modeling with RAW LiDAR and libLAS (Stuart Edwards)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 4 Mar 2011 09:05:09 -0500
> From: Stuart Edwards <sedwards2 at cinci.rr.com>
> Subject: Re: [Liblas-devel] Ground Modeling with RAW LiDAR and libLAS
> To: francesco <francesco.pirotti at unipd.it>
> Cc: liblas-devel at lists.osgeo.org
> Message-ID: <A32113F3-B8E1-4165-86EF-F33D6824193F at cinci.rr.com>
> Content-Type: text/plain; charset="windows-1252"
>
> GRASS GIS (open source) has several modules for processing raw LiDAR data
> and the ability to script your own classification routines. LibLAS does a
> nice job of preprocessing (decoding) the LAS files so they can be input to
> GRASS as x,y,z or general ASCII format .......see:
>
> http://grass.osgeo.org/wiki/LIDAR#Micro-tutorial
> Stu
>
>
> On Mar 4, 2011, at 1:31 AM, francesco wrote:
>
> > Hello List,
> > I just registered, hello to everyone.
> > Regarding Aaron's question, I am playing around with LibLAS to develop a
> ground classification procedure. It uses Axellson's progressive
> triangulation of local minimum points - but I am also looking at other
> solutions. Does anyone have other interesting approaches in mind?
> > Cheers,
> > Francesco
> > --
> > **************************************************
> > Francesco Pirotti
> > Dep. TESAF
> > CIRGEO – Interdepartmental Research Center on Cartography Photogrammetry
> > Remote Sensing and G.I.S.
> > University of Padova
> > Web: http://www.cirgeo.unipd.it/cirgeo/francescopirotti.htm
> > Email: francesco.pirotti at unipd.it
> > Phone: +39 049 827 2710
> > Phone: +39 349 55 39 261
> > **************************************************
> >
> >
> > Il 04/03/2011 00:49, Aaron Reyna ha scritto:
> >>
> >> Ah yes,
> >>
> >> I'll try the MCC-LiDAR. Great, thanks for the suggestion!
> >>
> >> Aaron
> >>
> >> On Thu, Mar 3, 2011 at 3:09 PM, Peter Tittmann <pwtittmann at ucdavis.edu>
> wrote:
> >> I've used MCC-Lidar http://sourceforge.net/apps/trac/mcclidar/ a little
> with marginal results. Not a great answer but something. TeraScan
> http://www.terrasolid.fi/en/products/terrascan is the elephant in that
> room.
> >>
> >> Peter
> >>
> >>
> >> On 03/03/2011 02:43 PM, Aaron Reyna wrote:
> >>> This may be too broad of a question, but has anyone seen or heard of a
> way to do efficient ground modeling with libLAS? That is, take raw LiDAR
> files (all default points) and model out the ground class? I do have raw
> LiDAR files if it helps.
> >>>
> >>> Just throwing it out there.
> >>>
> >>> Best,
> >>>
> >>> Aaron
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Liblas-devel mailing list
> >>> Liblas-devel at lists.osgeo.org
> >>> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >>
> >> --
> >> Peter Tittmann
> >> Geography Graduate Group
> >> UC Davis
> >> c. 707 849 4135
> >>
> >>
> >> _______________________________________________
> >> Liblas-devel mailing list
> >> Liblas-devel at lists.osgeo.org
> >> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >
> >
> > _______________________________________________
> > Liblas-devel mailing list
> > Liblas-devel at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/liblas-devel
>
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> ------------------------------
>
> Message: 2
> Date: Fri, 04 Mar 2011 15:29:11 +0100
> From: francesco <francesco.pirotti at unipd.it>
> Subject: Re: [Liblas-devel] Ground Modeling with RAW LiDAR and libLAS
> Cc: liblas-devel at lists.osgeo.org
> Message-ID: <4D70F737.7000901 at unipd.it>
> Content-Type: text/plain; charset="windows-1252"
>
> I use GRASS quite a lot, but always thought that it would be slow on
> vector points. I know Brovelli and her team developed some modules, I'll
> check on that. Good idea to use LibLAS as "driver" to turn LAS to xyz.
> Francesco
>
> Il 04/03/2011 15:05, Stuart Edwards ha scritto:
> > GRASS GIS (open source) has several modules for processing raw LiDAR
> > data and the ability to script your own classification routines.
> > LibLAS does a nice job of preprocessing (decoding) the LAS files so
> > they can be input to GRASS as x,y,z or general ASCII format .......see:
> >
> > http://grass.osgeo.org/wiki/LIDAR#Micro-tutorial
> > Stu
> >
> >
> > On Mar 4, 2011, at 1:31 AM, francesco wrote:
> >
> >> Hello List,
> >> I just registered, hello to everyone.
> >> Regarding Aaron's question, I am playing around with LibLAS to
> >> develop a ground classification procedure. It uses Axellson's
> >> progressive triangulation of local minimum points - but I am also
> >> looking at other solutions. Does anyone have other interesting
> >> approaches in mind?
> >> Cheers,
> >> Francesco
> >> --
> >> **************************************************
> >> *Francesco Pirotti*
> >> Dep. TESAF
> >> CIRGEO – Interdepartmental Research Center on Cartography Photogrammetry
> >> Remote Sensing and G.I.S.
> >> University of Padova
> >> Web: http://www.cirgeo.unipd.it/cirgeo/francescopirotti.htm
> >> Email: francesco.pirotti at unipd.it <mailto:francesco.pirotti at unipd.it>
> >> Phone: +39 049 827 2710
> >> Phone: +39 349 55 39 261
> >> **************************************************
> >>
> >>
> >> Il 04/03/2011 00:49, Aaron Reyna ha scritto:
> >>> Ah yes,
> >>>
> >>> I'll try the MCC-LiDAR. Great, thanks for the suggestion!
> >>>
> >>> Aaron
> >>>
> >>> On Thu, Mar 3, 2011 at 3:09 PM, Peter Tittmann
> >>> <pwtittmann at ucdavis.edu <mailto:pwtittmann at ucdavis.edu>> wrote:
> >>>
> >>> I've used MCC-Lidar http://sourceforge.net/apps/trac/mcclidar/ a
> >>> little with marginal results. Not a great answer but something.
> >>> TeraScan http://www.terrasolid.fi/en/products/terrascan is the
> >>> elephant in that room.
> >>>
> >>> Peter
> >>>
> >>>
> >>> On 03/03/2011 02:43 PM, Aaron Reyna wrote:
> >>>> This may be too broad of a question, but has anyone seen or
> >>>> heard of a way to do efficient ground modeling with libLAS?
> >>>> That is, take raw LiDAR files (all default points) and model
> >>>> out the ground class? I do have raw LiDAR files if it helps.
> >>>>
> >>>> Just throwing it out there.
> >>>>
> >>>> Best,
> >>>>
> >>>> Aaron
> >>>>
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> Liblas-devel mailing list
> >>>> Liblas-devel at lists.osgeo.org <mailto:
> Liblas-devel at lists.osgeo.org>
> >>>> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >>>
> >>> --
> >>> Peter Tittmann
> >>> Geography Graduate Group
> >>> UC Davis
> >>> c. 707 849 4135
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Liblas-devel mailing list
> >>> Liblas-devel at lists.osgeo.org
> >>> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >>
> >>
> >> _______________________________________________
> >> Liblas-devel mailing list
> >> Liblas-devel at lists.osgeo.org <mailto:Liblas-devel at lists.osgeo.org>
> >> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >
>
>
> --
> **************************************************
> *Francesco Pirotti*
> Dep. TESAF
> CIRGEO – Interdepartmental Research Center on Cartography Photogrammetry
> Remote Sensing and G.I.S.
> University of Padova
> Web: http://www.cirgeo.unipd.it/cirgeo/francescopirotti.htm
> Email: francesco.pirotti at unipd.it <mailto:francesco.pirotti at unipd.it>
> Phone: +39 049 827 2710
> Phone: +39 349 55 39 261
> **************************************************
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> ------------------------------
>
> Message: 3
> Date: Fri, 4 Mar 2011 08:27:55 -0600
> From: Howard Butler <hobu.inc at gmail.com>
> Subject: Re: [Liblas-devel] Ground Modeling with RAW LiDAR and libLAS
> To: francesco <francesco.pirotti at unipd.it>
> Cc: liblas-devel at lists.osgeo.org
> Message-ID: <12A13103-AB6D-471B-BB55-5184A70C58D9 at gmail.com>
> Content-Type: text/plain; charset=us-ascii
>
>
> On Mar 4, 2011, at 8:29 AM, francesco wrote:
>
> > I use GRASS quite a lot, but always thought that it would be slow on
> vector points. I know Brovelli and her team developed some modules, I'll
> check on that. Good idea to use LibLAS as "driver" to turn LAS to xyz.
>
> It would be much, much, much faster if someone wrote some glue between
> libLAS and GRASS (proposed here quite a while ago, but still not done <
> http://lists.osgeo.org/pipermail/grass-dev/2008-May/037687.html>). I
> would guess it would be an order of magnitude faster to ingest data if you
> didn't have to go through text formats to do it.
>
> And, for this LiDAR idiot. What is ground modeling?
>
> Thanks,
>
> Howard
>
> ------------------------------
>
> Message: 4
> Date: Fri, 4 Mar 2011 10:07:55 -0500
> From: Stuart Edwards <sedwards2 at cinci.rr.com>
> Subject: Re: [Liblas-devel] Ground Modeling with RAW LiDAR and libLAS
> To: francesco <francesco.pirotti at unipd.it>
> Cc: liblas-devel at lists.osgeo.org
> Message-ID: <0491F26F-08BF-4DCF-AF48-98D186F88A06 at cinci.rr.com>
> Content-Type: text/plain; charset="windows-1252"
>
> I don't find it to be particularly slow .... I guess it depends on how much
> processing you have to do. My uses are fairly limited so it's not a
> problem.
>
> Not quite on topic, but close, and something I'm trying to figure out --
> the LibLAS decoded file can provide all of the point data - not just x,y,z.
> This includes identification of 1st and 2nd arrivals which helps a lot in
> discerning vegetal cover from the ground surface.
>
> However, if you are going to filter on arrival time to get a ground surface
> data set you have to eliminate the 1st arrivals - but only if there's a
> second. If a second is absent (no vegetation at that location) then the 1st
> becomes the 'last' too. This makes interpretation more complicated and not
> just a matter of separating the 1s and 2s. I ended up writing a short
> script in octave to split the data into two pools - first arrivals and true
> last arrivals using the simple notion that a 1 is only a first if it is
> followed by a 2. If not, it's a last.
>
> Has anyone else wrestled with this?
>
> Stu
>
>
> On Mar 4, 2011, at 9:29 AM, francesco wrote:
>
> > I use GRASS quite a lot, but always thought that it would be slow on
> vector points. I know Brovelli and her team developed some modules, I'll
> check on that. Good idea to use LibLAS as "driver" to turn LAS to xyz.
> > Francesco
> >
> > Il 04/03/2011 15:05, Stuart Edwards ha scritto:
> >>
> >> GRASS GIS (open source) has several modules for processing raw LiDAR
> data and the ability to script your own classification routines. LibLAS
> does a nice job of preprocessing (decoding) the LAS files so they can be
> input to GRASS as x,y,z or general ASCII format .......see:
> >>
> >> http://grass.osgeo.org/wiki/LIDAR#Micro-tutorial
> >> Stu
> >>
> >>
> >> On Mar 4, 2011, at 1:31 AM, francesco wrote:
> >>
> >>> Hello List,
> >>> I just registered, hello to everyone.
> >>> Regarding Aaron's question, I am playing around with LibLAS to develop
> a ground classification procedure. It uses Axellson's progressive
> triangulation of local minimum points - but I am also looking at other
> solutions. Does anyone have other interesting approaches in mind?
> >>> Cheers,
> >>> Francesco
> >>> --
> >>> **************************************************
> >>> Francesco Pirotti
> >>> Dep. TESAF
> >>> CIRGEO – Interdepartmental Research Center on Cartography
> Photogrammetry
> >>> Remote Sensing and G.I.S.
> >>> University of Padova
> >>> Web: http://www.cirgeo.unipd.it/cirgeo/francescopirotti.htm
> >>> Email: francesco.pirotti at unipd.it
> >>> Phone: +39 049 827 2710
> >>> Phone: +39 349 55 39 261
> >>> **************************************************
> >>>
> >>>
> >>> Il 04/03/2011 00:49, Aaron Reyna ha scritto:
> >>>>
> >>>> Ah yes,
> >>>>
> >>>> I'll try the MCC-LiDAR. Great, thanks for the suggestion!
> >>>>
> >>>> Aaron
> >>>>
> >>>> On Thu, Mar 3, 2011 at 3:09 PM, Peter Tittmann <
> pwtittmann at ucdavis.edu> wrote:
> >>>> I've used MCC-Lidar http://sourceforge.net/apps/trac/mcclidar/ a
> little with marginal results. Not a great answer but something. TeraScan
> http://www.terrasolid.fi/en/products/terrascan is the elephant in that
> room.
> >>>>
> >>>> Peter
> >>>>
> >>>>
> >>>> On 03/03/2011 02:43 PM, Aaron Reyna wrote:
> >>>>> This may be too broad of a question, but has anyone seen or heard of
> a way to do efficient ground modeling with libLAS? That is, take raw LiDAR
> files (all default points) and model out the ground class? I do have raw
> LiDAR files if it helps.
> >>>>>
> >>>>> Just throwing it out there.
> >>>>>
> >>>>> Best,
> >>>>>
> >>>>> Aaron
> >>>>>
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> Liblas-devel mailing list
> >>>>> Liblas-devel at lists.osgeo.org
> >>>>> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >>>>
> >>>> --
> >>>> Peter Tittmann
> >>>> Geography Graduate Group
> >>>> UC Davis
> >>>> c. 707 849 4135
> >>>>
> >>>>
> >>>> _______________________________________________
> >>>> Liblas-devel mailing list
> >>>> Liblas-devel at lists.osgeo.org
> >>>> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >>>
> >>>
> >>> _______________________________________________
> >>> Liblas-devel mailing list
> >>> Liblas-devel at lists.osgeo.org
> >>> http://lists.osgeo.org/mailman/listinfo/liblas-devel
> >>
> >
> >
> > --
> > **************************************************
> > Francesco Pirotti
> > Dep. TESAF
> > CIRGEO – Interdepartmental Research Center on Cartography Photogrammetry
> > Remote Sensing and G.I.S.
> > University of Padova
> > Web: http://www.cirgeo.unipd.it/cirgeo/francescopirotti.htm
> > Email: francesco.pirotti at unipd.it
> > Phone: +39 049 827 2710
> > Phone: +39 349 55 39 261
> > **************************************************
> > _______________________________________________
> > Liblas-devel mailing list
> > Liblas-devel at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/liblas-devel
>
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>
> End of Liblas-devel Digest, Vol 39, Issue 2
> *******************************************
>
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