Sunday, 11 October 2015

clip - Clipping LAS data using shapefile polygons and open source software?



I am trying to clip or filter lidar files (.las, .xyz) using a shapefile that contains multiple polygons.


Is there open source software that can do this spatial operation?


My .las files are enormous, and I should say that I am very new to DEM data and analysis so any help would be very welcome.



Answer



I second @Michal Mackiewicz's answer (about Fusion/LTK), so I hope this example helps you getting through it.


This is the PolyCLipData syntax command (see the manual's page 110):


PolyClipData [switches] PolyFile OutputFile DataFile

Use an text editor to write the command before running it (such as NotePad++). Save the file with extension .bat (batch file). Don't forget to save the file before running it.


Assume you have:




  1. Fusion/LTK under the C: drive.

  2. the shapefile file (shapefile.shp) under C:\shapefile

  3. the las dataset (lasdata.las) under C:\las


write the following:


c:\fusion\polyclipdata c:\shapefile\shapefile.shp c:\las\clipped_data.las c:\las\lasdata.las

use the switch multifile if you want the las files generated from polygons to be stored in separate files. For example:


c:\fusion\polyclipdata /multifile c:\shapefile\shapefile.shp c:\las\clipped_data.las c:\las\lasdata.las 


use the shape switch together with multifile to name your multiple OutputFiles with values embedded in one of PolyFile's dbf column. For example if you want to name the files with the ID information (suppose ID is in the shapefile's first column). Write:


c:\fusion\polyclipdata /multifile /shape:1,* c:\shapefile\shapefile.shp c:\las\clipped_data.las c:\las\lasdata.las 



For clipping las files using PolyClipData with multiple single part shapefiles see the following post:
Clipping LAS data with multiple shapefiles


For clipping multiple las files having them embedded in a .txt file as the datafile parameter for PolyClipData, refer to the following post:
Clip multiple .las files data to polygon shapefile using FUSION


For clipping multiple las files with shapefiles using (with the LAStools Production toolbox) refer to the following post:

Clipping from a tiled LAS dataset with LASTools (for ArcGIS)


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