Using LiDAR in SURE

Integrating LiDAR into the SURE 2.5D and 3D workflows can greatly improve the quality of the final products (DSM, True Ortho, 2.5D Mesh, 3D Mesh). To learn more about the benefits of using LiDAR in SURE please visit our LiDAR Integration in SURE page. Here we demonstrate how to upload your LiDAR data into SURE in order to complement the image data for a more robust solution.

Related topics:


LiDAR Integration in SURE

Introduction


LiDAR data can be provided as part of the normal SURE Project definition wizard (both in GUI and CLI), as well as in custom workflows using either the 2.5D Tool or the Command Line Modules.

The LiDAR point clouds are provided by specifying the parent directory of the .las/.laz files. Alternatively, the user can specify a list text file with each entry pointing to the individual LiDAR .las/.laz files.

The LiDAR Trajectory file is provided as the path to the respective file.

SURE Project Definition 

GUI

CLI

CLI
SURE.exe -basepath <processing directory> -lidar-clouds <path to list or folder with LiDAR clouds> -lidar_trajectory <path to LiDAR trajectory> ...

See additional information at Project Setup article. 

SURE Custom Workflows

2.5D Tool

Command Line Modules


ModuleDsm.exe
ModuleDsm.exe --point-cloud-raw <Path_to Point_Cloud_Raw> --lidar-clouds <Path_to_LiDAR_points> ...

ModuleDsm.exe -h
Command Line Parameters:
  -h [ --help ]                         Print help screen
  --log arg (=log.txt)                  Path to logfile.
  --output arg (=.)                     Path to output folder.
  --gsd arg                             Value for ground sampling distance.
  --point-cloud-raw arg (=Internal/Lists/point_cloud_raw_list.txt)
                                        Path to raw point cloud (.las/.laz) or
                                        mesh (.osgb) list, file or folder.
  --lidar-clouds arg                    Path to LiDAR points (.las/.laz) list,
                                        file or folder.
  --no-lidar-clouds                     Disable usage of LiDAR data (modifies
                                        controlDsm.txt)
  --waterbody-shapefile arg             Path shapefile for waterbody surface.
  --controlfile arg (=Internal/Control_Files/controlDsm.txt)
                                        Path to controlDsm.txt control file.
  --area arg (=Internal/Control_Files/controlArea.txt)
                                        Path to controlArea.txt area file.
  --dsm-required-points-per-cell arg    Set DSM required points per cell
ModuleMesh.exe
ModuleMesh.exe -h
Command Line Parameters:
   -h [ --help ]                         Print help screen
  --log arg (=log.txt)                  Path to logfile.
  --output arg (=.)                     Path to output folder.
  --point-cloud arg (=Internal/Lists/point_cloud_list.txt)
                                        Path to point cloud list, file or
                                        folder.
  --lidar-clouds arg                    Path to LiDAR point cloud (.las/.laz)
                                        list, file or folder.
  --no-lidar-clouds                     Disable usage of LiDAR data (modifies
                                        control3DMesh.txt)
  --lidar-trajectory arg                Path to LiDAR trajectory file.
  --orientations arg (=Internal/Orientations)
                                        Path to orientations folder.
  --images arg (=Internal/Images/Match) Path to match images folder.
  --stereo-models arg (=Internal/Topologies/Topology.tif)
                                        Path to the project's topology.tif
                                        file.
  --point-cloud-meta arg (=Internal/Lists/point_cloud_meta_list.txt)
                                        Path to point cloud metainformation
                                        lists.
  --waterbody-shapefile arg             Path shapefile for waterbody surface
                                        (only used for LiDAR clouds, DIM clouds
                                        are handled in the point cloud step.
  --controlfile arg (=Internal/Control_Files/control3DMesh.txt)
                                        Path to control3DMesh.txt control file.
  --area arg (=Internal/Control_Files/controlArea.txt)
                                        Path to controlArea.txt area file.


Processing with LiDAR

If LiDAR data is provided as input during the project generation in SURE (versions post 3.0), then LiDAR will be automatically integrated into the workflow by default. Thus the user does not have to change any other setting regarding the processing of the new input. It is possible to turn off the usage of LiDAR individually for each of the processing steps (DSM or 3D Mesh), by disabling the respective parameters in the GUI or by using the --no-lidar-clouds Command-Line flag.

Performance optimization

It is recommended that the LiDAR point clouds are tiled in a scheme similar to the one employed in the SURE project. During the DSM step and the 3D Mesh step, the data is processed per tile. As such, SURE will load in memory all the necessary files that contain data which overlap with the currently processed tile. If the LiDAR data usage is enabled, this will include the DIM data, as well as the LiDAR data. Therefore the most optimal configuration - with minimum impact on processing time - will have the LiDAR point clouds tiled exactly as the DIM data. See also Georeferencing and Tiling.

The principle is illustrated below:

Sub-optimal 

Optimal

In the example below, it can be seen that the LiDAR Point Cloud Strips are much larger than the Area of Interest and thus SURE would have to load for every DIM tile the entire LiDAR strip.

Source: Leica - Bordeaux dataset

If the user would clip the LiDAR strips in a way that it suits the size of the DIM tile, then the processing of the DSM / Mesh will run faster (also less disk space will be used if Distributed processing is enabled). In the example below the LiDAR strips were clipped and exported as 8 individual smaller parts as the size of the DSM tile. Then a list containing the paths to these clouds was created and used as input in SURE.