What is LiDAR technology？How does it help with depth measurement？

Sensing technology is a key technology for embedded vision systems, and with the advancement of science and technology, more and more advanced technologies have emerged in the field of 3D depth sensing technology, including but not limited to Light Detection and Ranging (LiDAR), Stereo Vision, and Time of Flight (ToF). These technologies play an integral role in industries such as autonomous driving and factory automation.We learned about the ToF camera module earlier.
 
lidar technology is a high-precision 3D depth sensing solution that offers great advantages in terms of measurement accuracy, range and speed. 3D models of objects and environments, also known as point clouds, are created by firing laser pulses and measuring the time it takes for them to reflect back. This technology has not only improved the safety of self-driving vehicles, but has also shown great utility in areas such as geo-mapping, building modeling, and environmental monitoring.

 
Evolutionary history of 3D depth sensing technology

3D depth sensing technology first originated from passive stereo camera technology. This technology achieves depth perception by calculating the pixel difference between two sensors working in tandem. While very practical, it was still subject to low-light conditions and relied heavily on the texture of objects in the scene. To address the shortcomings of passive stereo cameras, active stereo vision techniques have emerged.
 
Active stereo vision technology utilizes an infrared patterned projector to illuminate the scene, which improves operation in poor lighting conditions and when object textures are not clear. However, it has no way to provide a wide range (within 10) of depth measurements, and the acquired data requires further processing to calculate the depth, which increases the computational burden while also affecting the real-time nature of the measurements. This is where the advantages of LiDAR technology come to the fore.

 
What is LiDAR technology?

what does lidar stand for？LiDAR technology, or Light Detection and Ranging, is an advanced remote sensing technology that calculates the precise distance of an object by emitting laser pulses and measuring the time it takes for those pulses to reflect back from the target object. This approach allows lidar scanner to create detailed 3D models, also known as point clouds, that accurately map the contours of objects and environments.LiDAR technology works in a similar way to radar (RADAR) but uses lasers rather than radio waves, and is capable of transmitting laser signals at a rate of up to 160,000 times per second, allowing for fast and accurate targeting of objects. enable fast, accurate measurements of target objects.
The formula for calculating the distance of an object is as follows:

Distance of object = (Speed of light x Time of flight) / 2.

 
This formula illustrates how LiDAR technology utilizes the speed of light and the time of flight of light pulses to calculate the distance, ensuring highly accurate and reliable measurements.

 
Two main types of LiDAR technology

LiDAR systems are categorized into two main types based on their function: airborne green light scanning and ground-based LiDAR.

 
Airborne LiDAR

Airborne 3D lidar tech sensors, usually mounted on drones or helicopters, emit light pulses to the ground and capture the return pulses to accurately measure distance. This technology can be subdivided into topological LIDAR, which is used to map the land surface, and bathymetric LIDAR, which uses green light to penetrate seawater and measure the elevation of the seabed and riverbeds.

 
Land Lidar

Land LIDAR systems are mounted on ground vehicles or fixed tripods and are used to map natural features of buildings and monitor highways. These systems are also valuable for creating accurate 3D models of historical sites. Land lidar scanner can be categorized into mobile LiDAR for moving vehicles and static LiDAR for stationary vehicles.

 
How LiDAR Cameras Function

The operation of LiDAR technology involves several key components.

1. Laser Source: Emits laser pulses at various wavelengths, with common sources including neodymium-doped yttrium aluminium garnet (Nd-YAG) lasers. Topographic lidar technology often uses 1064nm or 1550nm wavelengths for safety, while Bathymetric LiDAR employs 532nm lasers for water penetration.
2. Scanner and Optics: Utilizes deflecting mirrors to steer the laser beam, achieving a broad Field of Vision (FoV) and high-speed scanning capabilities .
3. Detector: Captures the reflected light from obstacles, typically using solid-state photodetectors like silicon avalanche photodiodes or photomultipliers. GPS Receiver: In airborne mode, the GPS receiver is a GPS receiver.
4. GPS Receiver: In airborne systems, tracks the altitude and location of the aircraft, crucial for accurate terrain elevation measurements. 
5. Inertial Measurement Unit (IMU): Monitors the speed and orientation of the vehicle, ensuring the precise positioning of the laser pulses on the ground .

 
Major Applications of LiDAR Technology

what is lidar application？Understanding the workings of LiDAR sensors is essential, but their real-world applications are where the technology truly shines.
 
1. Autonomous Vehicles and Equipment: Autonomous machinery, such as drones, autonomous tractors, and robotic arms, relies on 3D depth-sensing camera nodule for obstacle detection, localization, and the use of laser pulses on the ground. LiDAR sensors provide a 360-degree rotating laser beam, offering a comprehensive view for obstacle avoidance and object manipulation. LiDAR sensors provide a 360-degree rotating laser beam, offering a comprehensive view for obstacle avoidance and collision prevention. The real-time generation of millions of data points allows for the creation of detailed maps of the surroundings, enabling safe navigation in various weather and lighting conditions. 

 
2. Autonomous Mobile Robots (AMR): AMRs are integral to the operation of manufacturing facilities, warehouses, retail stores, and distribution centers, handling tasks such as item picking and distribution of goods. AMRs are integral to the operation of manufacturing facilities, warehouses, retail stores, and distribution centers, handling tasks like item picking, transportation, and sorting without direct human oversight. AMRs, as they require minimal processing for object detection and map creation, making them an ideal solution for these applications.

 
The advent of 3D depth sensing technologies

The advent of 3D depth sensing technologies, particularly LiDAR, has revolutionized the way we perceive and interact with our environment. From From enhancing the capabilities of autonomous vehicles to streamlining operations in industrial settings, LiDAR's impact is far-reaching. technologies continue to evolve, their applications will only expand, further integrating into our daily lives and shaping the future of technology.
 
With more than 14 years of experience in the embedded vision field, Sinoseen is committed to helping our customers provide the right camera modules to be integrated into their products, and we have worked with a number of drone and robotics companies to integrate our depth cameras into their products. If you are interested, please feel free to contact us.