[GRASS-user] Processing Atlas Lidar Data - Problem(s)
timmy_weyrer at live.at
Thu Mar 10 13:23:57 EST 2011
I´m trying to generate a DEM/DSM out of LIDAR data that I have downloaded
from the website http://atlas.lsu.edu/lidar/ .
The data can be downloaded as .csv-file. Within this file no attribute names
are given. For test purpose I manipulated the .csv, so that "only" 10,000
points were left and I added a row at the top "x,y,z" as attribute names.
After doing that I imported the .csv into QGIS using the Plugin "Add
Delimited Text Layer", stored the points as .shp-file and imported them into
GRASS GIS database using v.in.ogr (as 3D points).
Then I tried to follow the workflow described on the website
http://grass.osgeo.org/wiki/LIDAR#LIDAR_Tools (I started at "DEM/DSM
separation the more complex way").
The first step should be the use of v.extract to separate first and last
pulse laser points. Because of the reason that I have no information about
first/last pulse laser points, I skipped this step and tried to follow the
other steps. But I think this was for nothing, because v.lidar.edgedetection
needs the last pulse laser points and v.lidar.growing needs the first pulse
laser points. So I don´t write more about this...
I really don´t know how to generate a DEM/DSM based on this data and it
would be nice if anyone of you has an idea. Is there a possibility to do
generate a DEM/DSM without using the steps that are described within the
WIKI page above?
What do you think about the import of the .csv into GRASS GIS via QGIS? Is
there an easier way to import it?
If you need any further information to understand my problem, just let me
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