[GIS] Converting LiDAR data to raster (DEM/DSM) for ArcGIS input

arcgis-10.0arcgis-desktopdemlidarraster

I was wondering if there is an option to convert LiDAR data (.las) to a raster/grid (DEM/DSM) format that ArcGIS 10.0 can read?

Best Answer

The current option to import las files in ArcGIS is the LAS dataset data type. According to ESRI:

The LAS dataset provides fast access to large volumes of lidar and surface data without the need for data conversion.

If the surface (raster) you are trying to create is a bare-earth DEM refer to the following posts:

One option is the LAS dataset to Raster tool, but only when it is possible to filter1 the data by its ground returns. On the contrary, using the Cell Assignment Type argument equal Average or Minimum on unclassified data could (probably, 'would') result in bad DEMs. Mostly, the result will depend on the point cloud density, the terrain cover complexity, and the quality required in the output. It is important to (double) validate the DEM if going through this way.

1 Pay attention that to filter the LiDAR files in a LAS dataset it is necessary to generate a LAS dataset layer first (through the Make LAS dataset layer tool), or LAS dataset to Raster will consider all types of returns (just filtering using the LAS dataset properties for visualization won't work when processing data).

Another option for creating DEMs in ArcGis is to use the combination of Las to Multipoint tool for filtering ground points, and then, Point to Raster (it is probably less efficient than the first method, though).

Other workflows for creating DEMs from LiDAR data in ArcGIS are described in the post below. It also has insights about aspects which should be taken into consideration, when generating DEMs.

For working on DEMs starting from unclassified .las data I would suggest using more robust algorithms not yet available within the ArcGIS platform. For example:

On the other hand, if the surface (raster) is a Digital Surface Model - DSM refer to the following posts:

Input of .las/.laz files and conversion to .asc DSM (LASzip and Fusion).

Input of .las files and conversion to .asc DSM (LAStools).

Another option to import .las files in ArcGIS would be to convert them into ASCII (.txt, for example). Unless there is a specific reason for using plain text, previous options are better. The main differences working with .las or ascii files are approached in this post:

So, an alternative would be to use the command line LDA2ASCII from Fusion.

The LDA2ASCII syntax is:

LDA2ASCII InputFile OutputFile format

Suppose the following:

  • Fusion is stored under c:\Fusion.
  • the las file name is project.las.
  • project.las is stored in: c:\Lidar.
  • the new txt file will be saved at: c:\LiDAR.
  • its name will be: project.txt

Hint: use an text editor to write Fusion's program commands (e.g. Notepad++). Save it with .bat extension. Then, write:

Retrieve the following information: X, Y and Elevation. 

c:\Fusion\LDA2ASCII c:\Lidar\project.las c:\Lidar\project.txt 0

Or if the .las files contain other information such as: Pulse, Return, X, Y, Elevation, Nadir and Intensity: 

c:\Fusion\LDA2ASCII c:\Lidar\project.las c:\Lidar\project.txt 1

Save the .bat file, and then execute it (shortcut = F5)

Open project.txt in ArcGIS.

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