Analysis of UAV LiDAR Technology: Principles, Classification, and Applications

Unmanned Aerial Vehicle (UAV) LiDAR (Light Detection and Ranging) is a high-precision measurement technology based on laser remote sensing. This article begins with the fundamental concepts of lasers, radar, and LiDAR, systematically analyzing their connections and differences, and delves into the working principles, technical classifications, and practical applications of UAV LiDAR.

1. Laser

Laser stands for “Light Amplification by Stimulated Emission of Radiation.” Its basic principle involves electrons in atoms absorbing energy and transitioning to a higher energy level, then releasing photons when returning to a lower energy level. These photons exhibit highly consistent properties, forming laser light.

Compared to ordinary light sources, lasers offer the following significant advantages:

  • High monochromaticity
  • Strong directionality
  • High brightness

Based on the working medium, lasers are mainly classified into four types:

  • Gas lasers
  • Solid-state lasers
  • Semiconductor lasers
  • Dye lasers

2. Radar

Radar stands for “Radio Detection and Ranging.” It detects and measures the distance, speed, azimuth, and altitude of target objects by transmitting and receiving electromagnetic waves, making it also known as a radio positioning system.

Radar is essentially an electronic device whose core function is to detect and measure the parameters of target objects using electromagnetic waves.

3. LiDAR

LiDAR, or “Light Detection and Ranging,” is a laser-based detection and ranging technology. Although its name is similar to radar, the two differ significantly in technical principles and application methods.

Key Differences Between LiDAR and Radar:

  1. Wavelength Differences:
    • Radar uses radio waves, typically with wavelengths in the centimeter to decimeter range.
    • LiDAR uses laser light, typically with wavelengths in the nanometer to micrometer range.
  2. Equipment and Working Mechanisms:
    • The generation, transmission, and reception of electromagnetic waves involve entirely different devices.
  3. Naming Reason:
    • “Radar” is widely used to refer to detection and ranging systems, with “LiDAR” adding the “laser” prefix to highlight its technical features.

4. Classification and Measurement Principles of UAV LiDAR

UAV-mounted LiDAR systems are mainly divided into two categories:

  1. Phase-Based LiDAR:
    Achieves high-precision ranging by measuring the phase difference between emitted and returned laser light, similar to the principle of a total station.

  2. Pulse-Based LiDAR:
    Measures distance by calculating the time difference between the emission and return of laser pulses. Pulse-based LiDAR is currently the mainstream type used in UAVs.

5. Multi-Line LiDAR and 3D Data Acquisition

UAV LiDAR typically employs multi-line LiDAR (e.g., Hesai Pandar40), which is equipped with multiple laser emitters (e.g., 40 lines) distributed vertically at different angles. Through rotational scanning, it directly captures the three-dimensional coordinates of detected objects.

Technical Advantages:

  • High-speed, high-precision acquisition of large-scale 3D point cloud data
  • Data acquisition efficiency far exceeds that of traditional total stations, making it particularly suitable for large-scale geographic mapping

6. Coordinate System Integration with GPS and Attitude Measurement

In dynamic measurements, UAVs rely on the Global Positioning System (GPS) for coordinate calibration, functioning similarly to reverse positioning in a total station.

Relying solely on GPS is insufficient for high-precision measurements. Additional parameters are required:

  • Heading angle (angle relative to true north)
  • Attitude angles (horizontal angle and zenith angle)

These parameters together form the positioning and orientation system, replacing the traditional “leveling” process of total stations. Although UAVs cannot achieve physical leveling during motion, high-precision Inertial Measurement Units (IMUs) can monitor angle changes in real-time, ensuring data accuracy and reliability.

Summary

UAV LiDAR technology integrates laser ranging, multi-line scanning, GPS positioning, and IMU attitude measurement to achieve efficient and precise 3D environmental perception and geographic information acquisition. Its applications have widely covered fields such as surveying and exploration, construction engineering, smart agriculture, and disaster monitoring, making it a core component of modern spatial information technology.

Further Reading

Below are recommended readings on UAV LiDAR technology, covering authoritative technical analyses, application cases, and industry trends: