Splitting LAS file into smaller LAS files by shapefile geometry boundaries - using PDAL or Global Mapper.

Question

I've looked up pdal documentation on how to clip LAS point cloud files:- https://pdal.io/workshop/exercises/analysis/clipping/clipping.html

Referencing this example, and having a quick look around, it seems like there only is an option for one output file. Please correct me if I'm wrong.

I am after the input LAS files being split into four separate output LAS files (following the geometries of the indextile shapefile).

I was able to achieve this with the LASTools command lasclip.exe, however I've reached the limit of the 'unlicenced' version of lasclip:-

lasclip -i C:/a/test/BY17_1401merged_test.las -split -poly C:/a/cropped_topo50.shp -o newfile.las

https://www.cs.unc.edu/~isenburg/lastools/download/lasclip_README.txt

In the stdout for the above command;
WARNING: unlicensed. over 3 million points. output slightly distorted.
         tiny xyz noise. points permuted. intensity, gps_time, user_data
         and point_source_ID zeroed.

In the lasinfo report for one of the output LAS files. 
WARNING: real max x larger than header max x by 0.020000
WARNING: real min x smaller than header min x by 0.020000
WARNING: real max y larger than header max y by 0.020000
WARNING: real min y smaller than header min y by 0.020000
WARNING: real min z smaller than header min z by 0.010000

Is there any other way of splitting a LAS file into multiple output files using shapefile geometries? I have a Global Mapper license but cannot find a way to do it with this software. Unfortunately I was unable to get SAGA to work on my laptop and Whitebox is almost unusable (very slow) on my ubuntu computer.

Answer 1

The lidR package can do that in R

library(lidR)
library(sf)
ctg = readLAScatalog("C:/a/test/BY17_1401merged_test.las")
shp = st_read("C:/a/cropped_topo50.shp")
opt_output_files(ctg) = "C:/a/test/BY17_1401_split_{ID}"
with clip_roi
new_ctg <- clip_roi(ctg, shp)

This script references your file (or your files if several). It loads your shapefile. It assigns a templated output filename. Here your files will be named BY17_1401_split_1.las, BY17_1401_split_2.las and so on. Then it clips all your polygons by streaming the input file(s) into the output files. To finish it loads back a reference to the new created files.

The templated filename can be more elaborated. For example let assume that your table of attribute has a field names "OWNER" because the polygons describe land ownership your can:

opt_output_file(ctg) = "C:/a/test/BY17_1401_split_{ID}_{OWNER}"

Here your files will be named BY17_1401_split_1_bob.las, BY17_1401_split_2_alice.las and so on.