Clipping the LiDAR data with LASTools

The LiDAR data files I obtained didn’t exactly correspond to the area I want to map. I used LASTools to clip the files so that they only contained the data I’m interested in.

• Open the Windows command prompt:Win + X then Command prompt
• Navigate to the project folder: CD C:\GossanHill
• My project folder contains some LASTools these items:

ACT2015_8ppm-C3-AHD_6886096_55_0002_0002.las
ACT2015_8ppm-C3-AHD_6886098_55_0002_0002.las
ACT2015_8ppm-C3-AHD_6906096_55_0002_0002.las
ACT2015_8ppm-C3-AHD_6906098_55_0002_0002.las
las2las.exe
las2txt.exe
lasinfo.exe
laszip.exe

• Enter a command like this: las2las -i ACT2015_8ppm-C3-AHD_6886096_55_0002.las -o SW.las -keep_xy 688600 6096750 690325 6098200
• las2las is the program to run
• The -i ACT2015_8ppm-C3-AHD_6886096_55_0002.las part represents the input file
• The -o SW.las is the name of the output file we want to create. In this case, it is the south-western tile of interest. That explains the SW name.
• -keep_xy 688600 6096750 690325 6098200 is the instruction about which data to place in the output file. The four numbers represent the co-ordinates of the south-west corner and north-east corner of the rectangular mapping area we want to use. It doesn’t matter that the desired rectangle isn’t completely within any of the LiDAR data tiles.

The program runs for a little while, then you’ll see that a new file SW.las has been created. It is noticeably smaller than the input file.

I do the same thing three more times, changing the input and output file names as appropriate. Afterwards, my project folder has these items:

ACT2015_8ppm-C3-AHD_6886096_55_0002_0002.las
ACT2015_8ppm-C3-AHD_6886098_55_0002_0002.las
ACT2015_8ppm-C3-AHD_6906096_55_0002_0002.las
ACT2015_8ppm-C3-AHD_6906098_55_0002_0002.las
las2las.exe
las2txt.exe
lasinfo.exe
laszip.exe
NE.las
NW.las
SE.las
SW.las

I no longer need the large unclipped LiDAR files, so I delete them.

This article is part of the Orienteering Mapping with LiDAR, Smartphones and Free Tools series.

Polite and constructive responses are always welcome.