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Part 4

  • Introduction to LiDAR
  • Point data formats: ASCII, vector and LAS data

Digital elevation models

  • digital surface models (DSM)
  • digital terrain models (DTM)
  • vegetation height models (VHM)

Open source software for processing LAS data

  • las tools from Martin Isenburg (multiple license: partly open, partly commercial) lastools
  • las tools from Mateusz Loskot (BSD License): liblas
  • SPDLib from Pete Bunting: SPDLib
  • pktools creating and filtering DEM raster datasets from LAS files: pktools

Case study: LiDAR products in forestry

  • Input data: forest_31370.laz
  • Create digital surface model (DSM)
  • Create digital terrain model (DTM)
  • Create vegetation height model (VHM)
  • Create percentage height values (PHV)
  • Create intensity map

Set environment variables for input and output directories

export INPUTDIR=...
export OTPUTDIR=...

Extract basic information

from LAZ file

lasinfo $INPUTDIR/forest_31370.laz

from (APEX) hyperspectral dataset

gdalinfo $INPUTDIR/apex_ql.tif

using pktools

pkinfo -i $INPUTDIR/apex_ql.tif -dx -dy -bb

Create digital elevation models (DEM)

Digital surface model (DSM)

pklas2img -i $INPUTDIR/forest_31370.laz -o $OUTPUTDIR/forest_dsm.tif -a_srs epsg:31370 $(pkinfo -i $INPUTDIR/apex_ql.tif -dx -dy -bb) -comp max

Digital terrain model (DTM)

pklas2img -i $INPUTDIR/forest_31370.laz -o $OUTPUTDIR/forest_dem_min.tif -a_srs epsg:31370 $(pkinfo -i $INPUTDIR/apex_ql.tif -dx -dy -bb) -comp min
pkfilterdem -i $OUTPUTDIR/forest_dem_min.tif -o $OUTPUTDIR/forest_dtm.tif -f promorph -dim 3 -dim 17

Vegetation height model (VHM) -A $OUTPUTDIR/forest_dsm.tif -B $OUTPUTDIR/forest_dtm.tif --outfile=$OUTPUTDIR/forest_vhm.tif --calc="(A>B)*(A-B)"

Create percentage height values (PHV)

pklas2img -i $INPUTDIR/forest_31370.laz -o $OUTPUTDIR/forest_profile.tif -a_srs epsg:31370 $(pkinfo -i input/apex_ql.tif -dx -dy -bb) -comp profile -nbin 11

Create intensity map

pklas2img -i $INPUTDIR/forest_31370.laz -o $OUTPUTDIR/forest_intensity.tif -a_srs epsg:31370 $(pkinfo -i input/apex_ql.tif -dx -dy -bb) -fir first -n intensity -ot UInt16
wiki/pktools_lidar.txt · Last modified: 2017/12/05 22:53 (external edit)