Workflow for generating DEM from Lidar into ArcGis

Toolbox of several small scripts for processing Lidar point cloud and generating DTMs

Jules Fleury / SIGéo-CEREGE
Irene Puliti / CEREGE

The original datasets are point clouds with ground already classified

Steps :

1 – extract only ground from the classified point cloud
This is done with awk. See description at this site https://sigeo.cerege.fr/?p=199

ex. of command for processing a file :
awk ‘{ if ( $5!=1 ) print $0 }’ input.xyz > output.xyz
to batch it in bash :
for i in *.xyz; do awk ‘{ if ( $5!=1 ) print $0 }’ input.xyz > output.xyz; done

2- Convert ASCII XYZ file to LAS
This is done with ArcGis using the txt2las tool of LAStools, but it can also be done with libLAS or PDAL
The script in the ArcGIS toolbox is used in a batch mode

3- Convert LAS files to LAS datasets
we created a small python script based on Arcpy that we use add to a Toolbox and use it in batch mode
see “convert_las2lasd.py”

4- Convert Las datasets to TIN
we created a small python script based on Arcpy that we use add to a Toolbox and use it in batch mode
see “convert_lasd2tin.py”

5- Convert Tin to raster
we created a small python script based on Arcpy that we use add to a Toolbox and use it in batch mode
see “convert_tin2raster.py”

The scripts of steps 2 to 5 are used from a ArcGIS Toolbox