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Add a new LiDAR

RGLUnityPlugin (RGL) comes with a number of the most popular LiDARs model definitions and ready-to-use prefabs. However, there is a way to create your custom LiDAR. This section describes how to add a new LiDAR model that works with RGL, then create a prefab for it and add it to the scene.

Supported LiDARs

Not all lidar types are supported by RGL. Unfortunately, in the case of MEMs LiDARs, there is a non-repetitive phenomenon - for this reason, the current implementation is not able to reproduce their work.

1. Add a new LiDAR model

The example shows the addition of a LiDAR named NewLidarModel.

To add a new LiDAR model, perform the following steps:

  1. Navigate to Assets/RGLUnityPlugin/Scripts/LidarModels.

  2. Add its name to the LidarModels.cs at the end of the enumeration. The order of enums must not be changed to keep existing prefabs working.

    lidar_models

  3. Now, it is time to define the laser (also called a channel) distribution of the LiDAR.

    Info

    If your LiDAR:

    - has a uniform laser distribution
- has the equal range for all of the lasers
- fire all of the rays (beams) at the same time

    You can skip this step and use our helper method to generate a simple uniform laser array definition (more information in the next step).

    1. Laser distribution is represented by LaserArray consists of:

      • centerOfMeasurementLinearOffsetMm - 3D translation from the game object's origin to LiDAR's origin. Preview in 2D:

      • focalDistanceMm - Distance from the sensor center to the focal point where all laser beams intersect.

      • lasers - array of lasers (channels) with a number of parameters:

        • horizontalAngularOffsetDeg - horizontal angle offset of the laser (Azimuth)
        • verticalAngularOffsetDeg - vertical angle offset of the laser (Elevation)
        • verticalLinearOffsetMm - vertical offset of the laser (translation from origin)
        • ringId - Id of the ring (in most cases laser Id)
        • timeOffset - time offset of the laser firing in milliseconds (with reference to the first laser in the array)
        • minRange - minimum range of the laser (set if lasers have different ranges)
        • maxRange - maximum range of the laser (set if lasers have different ranges)

    2. To define a new laser distribution create a new class in the LaserArrayLibrary.cs

      lidar_array

      • Add a new public static instance of LaserArray with the definition.

      In this example, NewLidarModel laser distribution consists of 5 lasers with

      - elevations: 15, 10, 0, -10, -15 degrees
- azimuths: 1.4, -1.4, 1.4, -1.4, 1.4 degrees
- ring Ids: 1, 2, 3, 4, 5
- time offsets: 0, 0.01, 0.02, 0.03, 0.04 milliseconds
- an equal range that will be defined later

      Coordinate system

      Keep in mind that Unity has a left-handed coordinate system, while most of the LiDAR's manuals use a right-handed coordinate system. In that case, reverse sign of the values of the angles.

  4. The last step is to create a LiDAR configuration by adding an entry to LidarConfigurationLibrary.cs

    lidar_configuration

    Add a new item to the ByModel dictionary that collects LiDAR model enumerations with their BaseLidarConfiguration choosing one of the implementations:

    • UniformRangeLidarConfiguration - lidar configuration for uniformly distributed rays along the horizontal axis with a uniform range for all the rays (it contains minRange and maxRange parameters additionally)
    • LaserBasedRangeLidarConfiguration - lidar configuration for uniformly distributed rays along the horizontal axis with ranges retrieved from lasers description
    • Or create your custom implementations in LidarConfiguration.cs like:
      • HesaiAT128LidarConfiguration
      • HesaiQT128C2XLidarConfiguration
      • HesaiPandar128E4XLidarConfiguration

    Lidar configuration parameters descrition

    Please refer to this section for the detailed description of all configuration parameters.

  5. Done. New LiDAR preset should be available via Unity Inspector.

    done

    Frame rate of the LiDAR can be set in the Automatic Capture Hz parameter.

    Note: In the real-world LiDARs, frame rate affects horizontal resolution. Current implementation separates these two parameters. Keep in mind to change it manually.

2. Create new LiDAR prefab

  1. Create an empty object and name it appropriately according to the LiDAR model.
  2. Attach script LidarSensor.cs to created object.
  3. Set the new added LiDAR model in Model Preset field, check if the configuration loads correctly. You can now customize it however you like.
  4. (Optional) Attach script PointCloudVisualization.cs for visualization purposes.
  5. For publishing point cloud via ROS2 attach script RglLidarPublisher.cs script to created object.
  6. Set the topics on which you want the data to be published and their frame.
  7. Save the prefab in the project.

3. Test your prefab

  1. Create a new scene (remember to add the SceneManager) or use one of the existing sample scenes.

  2. Add the prepared LiDAR prefab by drag the prefab file and drop it into a scene.

  3. A LiDAR GameObject should be instantiated automatically

  4. Now you can run the scene and check how your LiDAR works.

Success

We encourage you to develop a vehicle using the new LiDAR you have added - learn how to do this here.