Creating a LAS dataset

Lidar data, and optional surface constraints can be added to a LAS dataset directly. A LAS dataset is created using either the Create LAS Dataset geoprocessing tool or the folder context menu. A LAS dataset is not stored in the geodatabase, but rather a binary file created and stored on disk. Creating a LAS dataset is a quick process as it is a pointer to LAS files and surface constraints stored on disk. The file extension that will be generated is a .lasd.

Ensure that the LAS files to be used in the LAS dataset are all reasonably sized. A recommended file size is approximately 25 to 50 MB, and no larger than 100 MB for optimal performance. The LAS files should not contain more than three million points per file when used in a LAS dataset.

There are two ways in which to create a LAS dataset: interactively through the context menu or through a geoprocessing tool. The two following sets of steps describe how to create a LAS dataset using either the context menu or the Create LAS Dataset geoprocessing tool.

Create a LAS Dataset using the context menu

The context menu in ArcCatalog or the Catalog window provides access to create a LAS dataset. This approach is recommended when interactively defining a LAS dataset.

Steps:

1. Right-click the folder where the LAS dataset is to be created to display the folder context menu.
2. From the context menu, click New > LAS Dataset.

3. Rename the LAS dataset from New Las Dataset to an appropriate name for the project.
4. Double-click the new LAS dataset to open the LAS Dataset Properties dialog box.
5. Select the LAS Files tab to add LAS files to the LAS dataset. You can either select the Add Files button or the Add Folder button to add LAS files to the new LAS dataset.
Note:

The Add Folder option is recursive. Therefore, adding a folder will allow LAS files in multiple folders in the selected folder to be added to the LAS dataset at one time.

6. Select the Surface Constraints tabs to add additional surface constraint data to the LAS dataset.
You can also remove any LAS files or surface constraints from the LAS dataset using the LAS Dataset Properties window using the Remove button on either tab.

Create a LAS Dataset using the geoprocessing tool

The Create LAS Dataset geoprocessing tool's primary use is for automating the creation of LAS datasets in scripts and in models.

Steps:

1. Open the Create LAS Dataset geoprocessing tool from the Data Management toolbox.
   
2. To specify the Input Files, select either File or Folder from the drop-down menu. Based on your selection, browse to either a single LAS file or to a folder containing a series of LAS files. If the specified LAS folder contains subfolders of LAS files, select the Include Subfolders option.
3. Optionally, specify any Input Surface Constraints and set the necessary surface properties for each.

   Surface constraints are surface features that should be enforced and displayed along with the LAS point cloud data. Breaklines, water polygons, or area boundaries are all examples of surface constraints. Surface constraints can be either feature classes or shapefiles. For each feature class you'll need to set properties that indicate how it is to be used to define the surface.

4. Optionally, specify an Input Coordinate System for the LAS dataset.

   LAS files should contain spatial reference information in the header portion of the LAS file. If an Input Coordinate System is set in the tool, then the tool will ignore any spatial reference information in the header of the LAS files. If an Input Coordinate System is not specified the spatial reference will be set to the spatial reference located in the header of the first LAS file which is encountered by the tool. In the case where there has been no spatial reference information given to the LAS files, and the Input Coordinate System is not set, then the LAS dataset will contain no spatial reference information.

5. Optionally, check Compute Statistics.

   Compute Statistics will generate a statistical report of the LAS files used in the LAS dataset. The statistics can be viewed in LAS dataset properties in ArcCatalog. Computing statistics requires a full scan of each LAS file to compute an in-depth statistical report, and therefore can take a lot of time to compute. It is recommended that this option only be checked on for workflows that require data quality analysis. For more information on the statistical analysis available with the LAS dataset in ArcGIS, see: Statistical analysis for LAS datasets.

6. Optionally, check Store Relative Paths.

   When using Store Relative Paths you are able to relocate the LAS dataset and LAS files relative to one another in the file system. They must remain in the same relative directory path from one another. If relative paths are not stored, and the LAS dataset or LAS files are relocated, then the LAS dataset will be broken and the LAS files will not be visible in ArcGIS.

7. Use the Output LAS Dataset option to set a location on disk where the LAS dataset will be created.