Understanding LiDAR Technology

Understanding LiDAR Technology

# What is LiDAR?

LiDAR (Light Detection and Ranging) uses laser pulses to measure distances with millimeter to centimeter precision. By measuring the time for light to reflect back, LiDAR calculates precise 3D coordinates for millions of points per second.

# How LiDAR Works

1. Pulse Emission
- Laser emits thousands of pulses per second
- Pulse rate: 100 kHz to 1+ MHz
- Multiple wavelengths available (near-IR common)

2. Surface Reflection
- Laser hits surface and reflects
- Multiple returns possible (vegetation)
- Return intensity recorded

3. Position Calculation
- Time-of-flight determines distance
- Scanner angle determines direction
- INS/GNSS determines scanner position

4. Point Generation
- XYZ coordinates calculated
- Intensity value assigned
- Classification possible (ground, vegetation, building)

# LiDAR Types

Terrestrial (TLS)
- Tripod-mounted
- Highest accuracy (sub-mm)
- Dense point clouds
- Limited range/coverage

Mobile (MLS)
- Vehicle or backpack mounted
- SLAM-based positioning
- Rapid coverage
- Moderate accuracy (5-20mm)

Aerial (ALS)
- Drone or aircraft mounted
- Large area coverage
- Vegetation penetration
- Accuracy: 2-10cm

# Key Specifications

Pulse Rate
- Higher = more points
- 100 kHz entry level
- 1+ MHz professional

Number of Returns
- Single: surfaces only
- Multiple: vegetation penetration
- Full waveform: detailed analysis

Accuracy
- Range accuracy
- Angular accuracy
- System accuracy (combined)