Sensor Configuration

Sensors are defined in the sensors array of an agent object. Each sensor is defined using a new dictionary in the list.

"sensors":[
   {
      "sensor_name": "FrontCamera",
      "sensor_type": "RGBCamera",
      "socket": "socket name",
      "location": [1.0, 2.0, 3.0],
      "rotation": [1.0, 2.0, 3.0],
      "Hz": 5,
      "lcm_channel": "channel_name",
      "ros_publish": "False",
      "configuration": {
         "array of sensor configurations"
      }
   }
]

Sensor Placement & Sockets

Sensors are placed on agents using sockets, locations, and rotations. Sensor placement can be defined in several ways:

Provide a socket name

This will place the sensor in the given socket.

{
   "sensor_type": "RGBCamera",
   "socket": "CameraSocket"
}

Provide a socket, location and/or rotation

The sensor will be placed offset to the socket by the location and rotation. The rotation is [roll, pitch, yaw] in degrees, rotated about XYZ fixed axes, ie R_z R_y R_x.
```
{
   "sensor_type": "RGBCamera",
   "socket": "CameraSocket"
   "location": [1.0, 2.0, 3.0],
   "rotation": [1.0, 2.0, 3.0],
}
```
Provide just a location and/or rotation

The sensor will be placed at the given coordinates, offset from the root of the agent.
```
{
   "sensor_type": "RGBCamera",
   "location": [1.0, 2.0, 3.0],
   "rotation": [1.0, 2.0, 3.0]
}
```

All sockets have standard orientation in the vehicle’s frame unless stated otherwise in the agent’s documentation. Standard orientation has the x-axis pointing towards the front of the vehicle, the y-axis pointing to the left, and the z-axis pointing upwards. See HoloOcean Agents for each vehicle’s available sockets, locations, and orientations.

Note

When viewing sockets in the Unreal Editor, the coordinate frame is left-handed, with the y-axis pointing to the right instead of left. HoloOcean handles the conversion between Unreal’s left-handed coordinates and the standard right-handed coordinates. When specifying locations and rotations in the scenario configuration, and when handling sensor returns, be sure to use right-handed coordinates.

Sensor Sample Rate

The sensor will be sampled at the rate specified in Hz. Note this must be less then ticks_per_sec, and preferably a divisor of ticks_per_sec as well. See Frame Rates for more info on ticks_per_sec.

{
   "sensor_type": "RGBCamera",
   "Hz": 20
}

Publish Message

HoloOcean supports publishing sensor messages and data to LCM. A HoloOcean-ROS2 Bridge package is also available.

To publish sensor data to LCM, specify the type to publish and the channel to publish to:

{
   "sensor_type": "RGBCamera",
   "lcm_channel": "CAMERA"
}

To publish sensor data to ROS2, set ros_publish to True:

{
   "sensor_type": "RGBCamera",
   "ros_publish": "True"
}

See Publishing Data Using ROS2 Bridge for more information on the ROS2 Bridge.

Configuration Block

The contents of the configuration block are sensor-specific. The configuration block is passed verbatim to the sensor itself, which parses it.

For example, the docstring for RGBCamera states that it accepts CaptureWidth and CaptureHeight parameters, so an example sensor configuration would be:

"sensors": [
   {
      "sensor_name": "RBGCamera",
      "sensor_type": "RGBCamera",
      "socket": "CameraSocket",
      "configuration": {
         "CaptureHeight": 1920,
         "CaptureWidth": 1080
      }
   }
]