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.
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2You haven't mentioned what software you have or are prepared to obtain. In ArcGIS there is a concept of a LAS Dataset resources.arcgis.com/en/help/main/10.2/index.html#//… 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 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 2 '18 at 22:14
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Thanks for this. I'm using ArcMap. Creating the dataset worked. – John_gis Oct 3 '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.
answered Oct 2 '18 at 22:14
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1Some things don't work so well in tiles, DEM for example, where triangulation over tile boundaries is a necessity, if you create a DEM from tiles there will be gaps around the edges or mismatches so it's better to mosaic first. LAS2DEM can process tiles individually to save memory and interpolate over the tile gaps if -i *.las is supplied as an input for a better end product. – Michael Stimson Oct 2 '18 at 22:18
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1@MichaelStimson, you are correct. I was initially thinking in just keeping the files as tiles (but missed writing about on the fly processing and 'edge artifacts'). I think the answer is better now. Tks. – Andre Silva Oct 2 '18 at 23:23
