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I downloaded about 9 LiDAR scenes from USGS and I want to use ArcMap to merge them so that I can carry out tasks on them together as opposed to one by one.

PolyGeo
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John_gis
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    You haven't mentioned what software you have or are prepared to obtain. In ArcGIS there is a concept of a LAS Dataset https://resources.arcgis.com/en/help/main/10.2/index.html#//015w0000005r000000 that will incorporate all LAS files into a single dataset. If you do not have ArcGIS you could try LASTools LAS2LAS -i *.las -o c:\your\path\Output.las to merge the files into a single las file https://rapidlasso.com/lastools/las2las/. Note that neither of these packages are free but LASTools is cheaper, significantly so if you're a student or researcher, and has more tools for visualizing LAS data. – Michael Stimson Oct 02 '18 at 22:14
  • Thanks for this. I'm using ArcMap. Creating the dataset worked. – John_gis Oct 03 '18 at 13:47

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Some tasks are indeed better off processing tiles altogether so to avoid 'edge artifacts' (like creating a DEM).

In this case, work with tiles using tools that can process them on-the-fly, like ArcGIS. Create a LAS Dataset and work form there. For example: Converting LiDAR data to raster (DEM/DSM) for ArcGIS input?.

Or work on a full merged file. For example, with MergeData tool from Fusion:. 

C:\Fusion\MergeData C:\lidar_data\*.las C:\lidar_data\output\alldata_merged.las

This will merge all .las files in directory C:\lidar_data, and will create a merged file named alldata_merged.las in the subfolder output.

Another option is larmerge from LAStools. See: Merging more than 9 input files with lasmerge?. LAStools can also merge files on-the-fly; take a look at examples from las2dem (search the switch -merged).

Still about LAStools, one can also use buffered tiles (also to avoid 'edge artifacts') while speeding up processing through parallel core usage.

Andre Silva
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