Skip to content

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 entry to the LaserArrayLibrary.cs

      lidar_array

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

      2. Add a new item to the ByModel dictionary that collects LiDAR model enumerations with their laser array definitions.

      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

    1. Add a new public static instance of LidarConfiguration with the definition:

      • laserArray - laser distribution array created in the previous step (it could be also generated uniformly with LaserArray.Uniform())
      • horizontalResolution - horizontal resolution of laser array firings in degrees (laser array will be rotated according to this resolution)
      • laserArrayCycleTime - time between two consecutive firings of the whole laser array in milliseconds. Usually, it consists of firing time for all the lasers and recharge time. Skip this parameter if all of the rays are fired at the same time.
      • minHAngle - minimum horizontal angle of the LiDAR
      • maxHAngle - maximum horizontal angle of the LiDAR
      • noiseParams - LiDAR noise parameters (see LidarNoiseParams.cs for more details)
      • rayGenerateMethod - if LiDAR has equal range for all of the lasers choose RotatingLidarEqualRange and configure minRange and maxRange in the LidarConfiguration. Otherwise, choose RotatingLidarDifferentLaserRanges and define ranges in LaserArray.
      • minRange - minimum range of the sensor (applied when Ray Generate Method is Rotating Lidar Equal Range)
      • maxRange - maximum range of the sensor (applied when Ray Generate Method is Rotating Lidar Equal Range)

    2. Add a new item to the ByModel dictionary that collects LiDAR model enumerations with their LiDAR configurations.

  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.