I downloaded about 9 LiDAR scenes from USGS and I want to use ArcGIS to merge them so that I can carry out tasks on them together as opposed to one by one.
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
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
Still about LAStools, one can also use buffered tiles (also to avoid 'edge artifacts') while speeding up processing through parallel core usage.