Implementation:CARLA simulator Carla ServerSideSensor

Knowledge Sources	CARLA
Domains	Client Library, Sensors, Data Streaming
Last Updated	2026-02-15 05:00 GMT

Overview

ServerSideSensor implements the client-side representation of a sensor that processes data on the server, providing methods for subscribing to sensor data streams, GBuffer texture access, and ROS2 integration.

Description

The ServerSideSensor class in the carla::client namespace handles sensor lifecycle management and data streaming for server-processed sensors (cameras, LiDAR, RADAR, etc.).

Lifecycle Management

The destructor implements careful cleanup:

• Warns if the sensor object goes out of scope while still alive in the simulation.
• If still listening and the episode is valid, stops all active GBuffer subscriptions and the main sensor stream.
• Uses a listening_mask bitset to track which streams are active (bit 0 for main sensor, bits 1-13 for GBuffer textures).

Main Sensor Stream

• Listen(callback) -- Subscribes to the sensor's data stream via GetEpisode().Lock()->SubscribeToSensor and sets bit 0 in the listening mask.
• Stop() -- Unsubscribes from the sensor stream and resets bit 0. Warns if not currently listening.
• IsListening() -- Checks if any bit in the listening mask is set.

GBuffer Access

Supports up to 13 GBuffer textures (defined by GBufferTextureCount):

• ListenToGBuffer(GBufferId, callback) -- Subscribes to a specific GBuffer texture stream. Only supported on RGB cameras (sensor.camera.rgb). Sets the corresponding bit in the listening mask.
• StopGBuffer(GBufferId) -- Unsubscribes from a specific GBuffer texture stream.

ROS2 Integration

• EnableForROS() -- Enables the sensor for ROS2 data publishing.
• DisableForROS() -- Disables ROS2 publishing for this sensor.
• IsEnabledForROS() -- Queries whether ROS2 publishing is enabled.

Destruction

• Destroy() -- Overrides Actor::Destroy() to stop all GBuffer subscriptions and the main stream before destroying the actor.

Usage

Server-side sensors are spawned via blueprints and attached to vehicles or placed in the world. Call Listen with a callback to start receiving sensor data. Use GBuffer methods for advanced rendering pipeline access on RGB cameras.

Code Reference

Source Location

• Repository: CARLA
• File: LibCarla/source/carla/client/ServerSideSensor.cpp (109 lines)

Signature

namespace carla {
namespace client {

class ServerSideSensor : public Sensor {
public:
  void Listen(CallbackFunctionType callback);
  void Stop();
  bool IsListening() const;

  void ListenToGBuffer(uint32_t GBufferId, CallbackFunctionType callback);
  void StopGBuffer(uint32_t GBufferId);

  void EnableForROS();
  void DisableForROS();
  bool IsEnabledForROS();

  bool Destroy() override;

  ~ServerSideSensor();

private:
  std::bitset<GBufferTextureCount + 1> listening_mask;
};

} // namespace client
} // namespace carla

Import

#include "carla/client/ServerSideSensor.h"

I/O Contract

Inputs

Name	Type	Required	Description
callback	CallbackFunctionType	Yes	Callback function invoked with sensor data each frame
GBufferId	uint32_t	Yes (for GBuffer methods)	GBuffer texture index (0-12)

Outputs

Name	Type	Description
Sensor data	via callback	Sensor measurements delivered through the registered callback
IsListening	bool	Whether the sensor is currently subscribed to any stream
IsEnabledForROS	bool	Whether the sensor publishes data to ROS2
Destroy result	bool	Whether the sensor was successfully destroyed

Usage Examples

// Spawn a camera sensor
auto camera = world.SpawnActor(camera_bp, transform, vehicle);
auto sensor = std::static_pointer_cast<carla::client::ServerSideSensor>(camera);

// Start receiving data
sensor->Listen([](auto data) {
    auto image = std::static_pointer_cast<carla::sensor::data::Image>(data);
    // Process image...
});

// Access GBuffer for advanced rendering (RGB camera only)
sensor->ListenToGBuffer(0, [](auto data) {
    // Process GBuffer texture 0...
});

// Enable ROS2 publishing
sensor->EnableForROS();

// Stop and cleanup
sensor->Stop();
sensor->Destroy();

Related Pages

• Environment:CARLA_simulator_Carla_Simulation_Runtime
• CARLA_simulator_Carla_Actor_Class - Base Actor class
• CARLA_simulator_Carla_Python_SensorData_Bindings - Python bindings for sensor data
• CARLA_simulator_Carla_ROS2_Bridge - ROS2 bridge that publishes sensor data