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@hotmail.com
Date: Wed, 12 Jan 2011 15:29:41 +0100
Subject: Re: [GRASS-user] From pointcloud to dem - help
From: markus.metz.giswork@googlemail.com
To: jornanke@hotmail.com
CC: grass-user@lists.osgeo.orgOn Wed, Jan 12, 2011 at 2:17 PM, Jorn Anke jornanke@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