[GRASS-user] From pointcloud to dem - help‏

[Jorn Anke]

Dear all,

I have been trying to import a pointcloud into GRASS, by 
following Markus' direction as quoted below. The import of the pointcloud into 
GRASS works fine, but since I am quite new to GRASS, I have problems with the 
next logical steps - and in producing any meaningfull/viewable results.

I 
have uploaded the pointcloud-file: pc_xyzrgb.txt at a forum;  
http://uavmapping.com/forum/index.php?topic=17.0

It  would be great if 
anyone would download the pointcloud and post a few examples of how to produse 
and display results. (Besides explanaition of the 
steps).


Background:
I have been writing a software/tool for 
georeferencing pointclouds from MS Photosynth/PMVS, by the use of 3D affine 
transformation. The objective is to use GRASS to produce digital elevation 
models out of the pointclouds, and to output the dem's into file-formats 
suitable for distribution to end 
users.


Jørn,
jornanke at hotmail.com


> Date: Wed, 12 
Jan 2011 15:29:41 +0100
> Subject: Re: [GRASS-user] From pointcloud to dem 
- help
> From: markus.metz.giswork at googlemail.com
> To: 
jornanke at hotmail.com
> CC: grass-user at lists.osgeo.org
> 
> On 
Wed, Jan 12, 2011 at 2:17 PM, Jorn Anke <jornanke at hotmail.com> 
wrote:
> >
> > Dear Grass users,
> >
> > I 
have a pointcloud form PMVS
> > 
(http://grail.cs.washington.edu/software/pmvs/) consisting of near to 6
> 
> million points.
> >
> > The pointclouddata is 
georeferenced into world-coordinates (EUREF-89), and
> > stored in a 
text file with the following format: X Y Z R G B. (RGB colordata
> > 
can be deleted if required).
> >
> > What I want to do is to 
import the pointcloud into Grass 7.0, and to
> > generate a surface 
modell/ dem, and to export the dem to a common
> > file-format, e.g. 
ESRI SHP or Land-XML.
> >
> > I am quite new to Grass, so I 
would very much appreciate a brief description
> > of the steps I will 
need to go through in order to obtain this.
> >
> First, import 
the point cloud with v.in.ascii. You can then filter the
> points with the 
lidar tools to remove outliers (v.outlier) and obtain
> a digital terrain 
model and a digital surface model
> (v.lidar.edgedetection, 
v.lidar.growing, v.lidar.correction). The
> v.surf.* modules can create a 
(raster) DEM by interpolating the
> points. GRASS prefers raster maps for 
surface/terrain representation;
> that also means that ESRI SHP or 
Land-XML being vector formats are not
> really appropriate for a DEM. 
Common raster formats are e.g. GeoTIFF,
> Erdas Imagine, or ESRI .hdr 
[1].
> 
> Markus M
> 
> [1] 
http://www.gdal.org/formats_list.html
  		 	   		  
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