Starting from the Metashape Professional 2.0.0, the program supports unstructured aerial laser scans data processing. The result of aerial laser scanning is a 3D array of laser reflection points, which can be uploaded to Metashape project and processed.


The tutorial below describes the main workflow processing steps:


Import Trajectory

The scanning trajectory for laser scan data can be imported in Metashape. The following formats are supported for the trajectory import:  Character-separated values (*.txt, *.csv, *.trjt, *.xyz), SBET (*.out, *.sbet), SOL (*.sol), TerraScan (*.trj).


In order to be used properly, the trajectory should be imported to the project prior to the import of the laser scan data. 


1. Select File > Import > Import Trajectory command to import trajectory. 


2. Select the file with the trajectory. For character-separated values formats specify the following parameters: Columns (X, Y, Z, GPS Time), Delimiter (Tab, Comma, Semicolon, Space or other) and Skip rows in the Import Trajectory dialog window. For other formats, the data will be loaded automatically.


3. Click OK button.


The trajectory will be displayed in the Model view and new layer with the trajectory will also appear in the Workspace pane. The trajectory can be displayed as various modes: Solid View, Elevation View, Time View. 




In Elevation and Time view modes, the red value corresponds to the largest value, the blue value corresponds to the smallest.


For convenient work with the aerial laser scan (for example, displaying only part of the point cloud, or the exclusion of a turning area), masking tools for the trajectory (Mask Selection, Unmask Selection, Crop Mask by Selection, Reset Mask) are implemented in Metashape. 


The tools are available in the Tools > Trajectory menu. To apply masking, first select the desired area in the Model view using the Selection tools on the toolbar. 



Then select the desired command for masking from the Tools menu (in the example below we used - Crop mask by selection): 



Select Tools > Trajectory > Reset Mask command to reset mask: 



Import aerial LiDAR data

The laser scan point cloud can be imported in the following formats: ASPRS LAS (*.las), LAZ (*.laz), ASTM E57 (*.e57), ASCII PTS (*.pts, *.pts.gz), PTX (*.ptx), Stanford PLY (*.ply), Wavefront OBJ (*.obj),  Point Cloud Data (*.pcd).


1. To import laser scans select File > Import > Import Point Cloud command.


2. In the Import Point Cloud dialog box browse to the folder containing the laser scans and select the corresponding files. Then click Open button.


Multiple point clouds can be loaded at the same time. Select all point clouds from the folder with laser scans data for importing. In this case the parameters from the Import Point Cloud dialog window will be applied to all the selected point cloud files.

3. Set the parameters for import and enable checkbox Use as laser scans in the Import Point Cloud dialog window.




The Trajectory option for the Scanner position parameter is available only if the trajectory has been imported to the project prior to the point cloud import.
If the option Use as laser scans was not enabled in the Import Point Cloud dialog window, it is possible to enable this command in the Point Cloud context menu, after it was imported in the project and reflected in the chunk's content on the Workspace pane. 
You may choose all point clouds related to the laser scans and apply Use as Laser Scans command.



The following parameters can be changed in the Import Point Cloud dialog box:

  • Coordinate System: Set coordinate system from the dropdown list or upload parameters of a customized geographical coordinate system corresponding to the point clouds being imported.
  • Coordinate Precision: To specify a custom value for coordinate precision enable Custom option and add the value in the corresponding field. Alternatively use Default option, then Metashape calculates coordinate precision automatically. The calculated value corresponds to the average density value for all points from the point cloud.
  • Parameters: To import the point cloud as a laser scan, enable the Use as laser scans parameter. If the point normals are not stored in the files being imported, Metashape would calculate the point normals automatically. To determine the normal of a point in a point cloud, Metashape approximates the local surface of the model with a plane. If the point cloud was obtained in an unstructured form, then Unknown option should be selected in the Scanner Position field. If the point cloud was recorded in a structured form, then the Origin parameter should be selected. If point cloud saves a trajectory file, then use - Trajectory parameter value.

The direction of the approximation plane is determined by the nearby neighbors of a given point. The number of nearby points to consider is defined by Normal estimation neighbors parameter value. If the imported cloud is very noisy, 28 (default value) neighbors may not be enough to determine the normals confidently. For such point clouds, it is worth increasing the Normal estimation neighbors value up to 100. Increasing the number of neighbors will slow down the calculation, smooth out the normals at the corners, but will help to avoid noise. In some cases, increasing the number of neighbors can also help to avoid large plots with the inverted normals.


4. Click OK button to add the data into project.




If the trajectory file was not uploaded before the point cloud import, then it can be applied after the point cloud was uploaded as laser scans. Import the trajectory file (select File > Import > Import Trajectory), and choose Set Trajectory > Trajectory command from the laser scans context menu. The process is shown on the animation below:



To show or hide laser scans in the Model view use Show Laser Scans toolbar button:



Depending on the information recorded in the laser scan data, the cloud can be displayed as various modes: Solid View, Colors View, Classes View, Intensity View, Elevation View, Return View, Scan Angle View, Source ID View, Confidence View:



Based on the imported laser scan point cloud it is possible to perform classification, build DEM and build mesh. For the purpose select Laser Scans as Source data on the corresponding processing step. See an example of the dialog window below:



If the project includes both laser scans data and digital imagery for the same scene, all the data should be loaded to the same chunk and to be processed together. In this case you can also build texture, orthomosaic and tiled model.