Overview of Chrono::Sensor

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The Chrono::Sensor module provides support for simulating RGB cameras, lidar, radar, GPS, and accelerometer, gyroscope, and magnetometer within a Chrono simulation. Sensors are objects that are attached to Chrono Bodies(ChBody). Chrono::Sensor is currently compatible with the core rigid body simulation in Chrono including Chrono::Vehicle.

Detailed overview of Chrono::Sensor.

How the sensor system is setup (more examples can be found in the sensor demos)

import ..

// Chrono
ChSystemNSC mphysicalSystem

// ...

// Setup and initialize sensors and sensor system (manager and environment)
auto manager = chrono_types::make_shared<ChSensor>();

// Setup and customize the scene
manager->scene->AddPointLight({x,y,z}, {intensity, intensity, intensity}, distance);
manager->scene->SetAmbientLight({0.1, 0.1, 0.1});

// Set sky gradient
Background b;
b.mode = BackgroundMode::GRADIENT;
b.color_horizon = {.6, .7, .8};
b.color_zenith = {.4, .5, .6};
manager->scene->SetBackground(b);

// Add some sensors
// see sensor specific pages for adding sensors to manager

// Simulation loop
while(){

  // update the sensor manager
  manager->Update();

  // perform step of dynamics
  mphysicalSystem.DoStepDynamics(step_size);
}

Chrono::Sensor design considerations

Since dynamic chrono simulations typically have a higher update frequency than sensors (dynamics: order 1kHz; sensors: 10-100Hz), the sensor framework uses a separate thread to manage the data curation.

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Chrono::Sensor can leverage multiple render threads each managing a separate GPU for simulating a group of sensors. This is particularly useful for scenarios with multiple agents and numerous sensors that operate at various update frequencies.

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Each sensor has a filter graph which users can extend to customize the computation pipeline for modeling specific sensor attributes or configuring specific data formats.

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Loading sensor models from JSON Files

auto cam = Sensor::CreateFromJSON(
  GetChronoDataFile("sensor/json/generic/Camera.json"),   // path to json file
  my_body,                                                // body to which the sensor is attached
  ChFramed(ChVector3d(-5, 0, 0), QUNIT));                 // attachment pose for the sensor

  // add camera to the manager
  manager->AddSensor(cam);

Reference Frames and Relative Attachment Positions

Each Chrono sensor defaults to Z-up, X-forwad, and Y-left to match a vehicle ISO reference frame. For an RGB camera, this means that the z-axis points vertically in the image plane, the y-axis points left in the image plane, and the x-axis points into the image plane. For lidar, the x-axis point along rays with zero vertical angle and zero horizontal angle