The LiDAR sensor is a type of depth sensor that accurately performs 3D mapping using laser pulses. It can be found in smartphones, autonomous cars, drones, and augmented reality devices.
LiDAR stands for "Light Detection and Ranging." The fourth generation of the iPad Pro was the first to feature a built-in LiDAR sensor in the rear camera, and the iPhone 12 Pro and Pro Max were among the first smartphones to adopt this technology.
How the LiDAR Sensor Works
The LiDAR sensor emits laser pulses that hit objects and detects the pulses that are reflected back. It measures the time it takes for the pulse to make this round trip and calculates the distance to the object based on that. This process is repeated millions of times per second, generating a point cloud with data, time, and location. This data is used to create a real-time 3D map of the environment with precise spatial information.
Main Components of LiDAR Devices
- Laser emitter: emits infrared light pulses that spread throughout the environment.
- Scanner: distributes the laser beams, regulates their speed and distance for scanning the environment.
- LiDAR sensor: detects light, registering each pulse that is reflected back to the device to measure the depth of field.
- GPS: tracks and records the location of the LiDAR system, using satellite data to validate distances between objects.
LiDAR can "see" in 3D under any lighting conditions because it has its own light source. The sensor is usually placed alongside traditional cameras, which only produce 2D images of the environment and are affected by intense sunlight, darkness, and reflections.
The functioning of the LiDAR sensor is similar to that of radar: both calculate distances by emitting a signal and measuring the time it takes to return. The key difference is that LiDAR uses light waves, while radar emits radio waves.
LiDAR generates more detailed 3D images but has a range that varies from 4 meters to 45 kilometers. Meanwhile, radar produces less precise depth maps but can detect objects within a range of up to 500 kilometers.
LiDAR vs. Time-of-Flight (ToF) Sensors
LiDAR is a type of Time-of-Flight (ToF) sensor that includes a scanner to distribute laser beams. Every ToF depth sensor uses Time-of-Flight measurement to calculate the distance to an object. This technique involves emitting light waves and measuring how long they take to be reflected back.
The main advantage of LiDAR over other 3D ToF sensors is its greater range: from 4 meters to 10 meters in indoor spaces, up to 200 meters in autonomous cars, and 1 kilometer to 45 kilometers in space applications, as explained by the Swiss university EPFL.
LiDAR sensors tend to be more expensive than other 3D ToF alternatives because they require more complex components and more precise laser technology.
Applications of LiDAR Technology: From Smartphones to the Automotive Sector
Smartphones and Tablets
LiDAR is integrated into the rear camera of iPhone and iPad Pro models, allowing for faster autofocus, especially in low light, and providing greater accuracy for augmented reality apps via ARKit.
Robotic Vacuum Cleaners
LiDAR enables more precise mapping of environments, preventing the vacuum cleaner from "swallowing" small objects on the floor. This technology is present in devices like the Samsung Jet Bot+ and Jet Bot AI+.
Smart Cars
LiDAR scanners map the surrounding world and assist in vehicle automation, enabling cars to drive with less human supervision.
Public Safety
LiDAR can be used similarly to a speed radar and can map urban areas for planning police or military operations.
Astronomy
NASA uses LiDAR on the Ingenuity helicopter to maneuver it safely on the surface of Mars.
Mapping
LiDAR systems collect three-dimensional measurements of terrains (topography), buildings (architecture), highways, and indoor environments.
Environment
Laser scanning with LiDAR allows mapping of flood risks, coastal erosion, and carbon stocks in forests.
Atmospheric Physics
The sensor helps collect weather data and detect types of particles in the air.
Limitations of the LiDAR Sensor
- Cost: LiDAR systems are more expensive than other depth measurement techniques such as 3D ToF sensors.
- Colorless and Textureless Images: It can be challenging to interpret LiDAR data without overlaid images from a traditional camera.
- Interference: The device can interfere with other nearby LiDAR sensors if they scan the same area simultaneously.
- Atmospheric Noise: Airborne debris that exists between the light transmitter and the object can affect distance measurements.