LiDAR QC Processing

LiDAR QC is an advanced trajectory processing technology that, similar to LiDAR SLAM, is using scan data as an aiding sensor to improve georeferencing accuracies in areas of poor GNSS coverage or in areas where overlapping scans are not perfectly matching. Based on a robust and iterative least square adjustment, LiDAR QC generates 3D Voxels that are matched in overlap scan regions. The result of this iterative process is solving the constant IMU boresight angles and making corrections to the post-processed trajectory (position and orientation).

  • Calibration Pattern:
    • Area:

      - Choose a structured scene such as a residential area with detached houses and objects within the LiDAR sensor's maximum range.
      - Ensure the area has open sky terrain for good GNSS satellite visibility.
    • Strips:

      - Plan for two perpendicular strips. Each strip will consist of two runs (one in each direction).
      - The length of each strip should be between 250-300 meters.
  • System Requirements:
    • CPU:

      - Recommended: Intel XEON
      - Minimal: Intel Core i7 or i9
    • Memory:

      - Recommended: 256 GB RAM
      - Minimal: 128 GB RAM
    • Storage for TEMP Folder:

      - Recommended: 2 TB SSD M.2 module (connected directly to the PCI bus)
      - Minimal: 1 TB SSD (connected to PCI bus)
    • TEMP and TMP Folder Configuration: Define the TEMP and TMP folders to point to the SSD drive.

      Detailed instructions are described below:

      1 - Type “environm” into the Windows Search box and select “Edit the system environment variables”. The "System Properties" dialog opens.
      2 - In the "Advanced" tab, select "Environment variables". The "Environment variables" opens.
      3 - In the "User variable for your account", define the TEMP and TMP folder pointing to the SSD drive.
    • Virtual Memory:

      - Virtual memory should be 6 times the installed RAM.
      - Recommended: An additional disk of 2 TB SSD M.2 on the PCI bus (or 4 TB combined with the TEMP disk)
      - Minimal: An additional 1 TB SSD, always available

      Detailed instructions are described below:

      1 - Type “environm” into the Windows Search box and select “Edit the system environment variables”. The "System Properties" dialog opens.
      2 - In the "Advanced" tab, select “Settings” in the "Performance" panel. The "Performance Options" dialog opens.
      3 - In the "Advanced" tab, select "Change" in the "Virtual Memory" panel. The "Virtual Memory" dialog opens.
      4 - Uncheck the "Automatically manage paging file size for all drives" option.
      5 - Select your SSD Drive and assign the paging file size.
      6 - Select the "Customize size" option.
      7 - Set “Initial size” to installed RAM on your computer.
      8 - Set the “Maximum size” to 6 x installed RAM.
    • MATLAB: Install the MATLAB Runtime version R2021b (9.11) after installing TBC. The MATLAB Runtime enables the execution of compiled and packaged MATLAB applications within TBC without the need to install MATLAB itself. You can download it from the MathWorks website at https://fr.mathworks.com/products/compiler/matlab-runtime.html.

      Note: For detailed guidance on defining the TEMP and TMP folders and adjusting the virtual paging file, you can reach out the Applanix Support Team or visit the Customer Support Portal.

  • LiDAR QC Settings:
    • Range: Defines the minimum and maximum distance of LiDAR measurements being used in the LiDAR QC process. Measurements outside this range should be filtered out to avoid blunders and unnecessary data. The unit of the Ranges values is meter [m], and the default values are 3 m and 100 m.
    • Noise: Refers to the selection of the precision level for LiDAR distance measurements. There are six predefined values (5 mm, 10 mm, 50 mm, 80 mm, 100 mm and 200 mm), and the default value is 5 mm for an MX 50/60 and 10 mm for an MX 9/90.
    • Lasers: Decide between using either the Left, Right, or both lasers for computation. Choosing a single laser can help speed up the process as it limits the computation to the sections having overlaps only. If both lasers are involved, the computation time can increase without significantly improving the accuracy, as it compares the left versus right laser of isolated runs. The default value is All.
  • LiDAR QC Processing:
    1. Select the runs from the Project Tree with overlap (parallel runs, or crossing runs) and click Add.
    2. Define the settings as described above.
    3. Click Compute.