LASmoons: Asger S. Petersen

Asger S. Petersen (recipient of three LASmoons)
Copenhagen, Denmark
Partner & Consultant, Septima

Background:
The Danish Geodata Agency has acquired country wide LiDAR coverage. Approximately 1/4th of the country has been flown this spring and the GST has published preliminary classified point cloud data. There are a lot of people in the Danish geodata community who are very excited to get to know this new data.

lasmoons_asger_petersen_0

Goal:
I would like to produce a hill shaded DTM and DSM from these data and publish them as a freely available web map for all to give those interested a first glance at this new and exciting data set.

Data:
+ 400 square kilometres of LIDAR from the western part of Zealand
+ average point density: 4 pts/m2

LAStools processing:
1)
unzip LAS (unfortunately compressed as *.las.zip instead of *.laz files)
2) lower excessive resolution from [mm] to [cm] with ‘-rescale 0.01 0.01 0.01′, add missing projection information with ‘-utm 32N’, re-tile with ‘-buffer 35′, and compress with ‘-olaz’ (lastile)
3) create 0.4 meter DTM and DSM elevation raster tiles (las2dem)
4) calculate hill shade and pseudo color rasters for presentation using QGIS

Using the unlicensed version of LAStools in combination with QGIS I was able to produce hillshaded DTMs at a resolution of 40 cm (without edge artifacts) from approximately 80 GBs of zipped LAS (sic!) files in an afternoon.

References:
Geodatastyrelsen (2013), Danmarks Heojdemodel bliver bedre og mere noejagtig, Web post from 29 November 2013 (available here on 14 May 2014).
Geodatastyrelsen (2014), Twitter message from 28 April 2014 (available here on 14 May 2014).

lasmoons_asger_petersen_2

lasmoons_asger_petersen_1Results:
Asger has been hard at work to set up the infrastucture for the Web map which “has taken 10 times as long as the data processing.” The landing page can be found here. It describes the process and the data in Google translated Danish-English. If you want to skip directly to the big map it can be found here.

 

 

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