LiDAR (Light Detection and Ranging) sensors work by emitting laser pulses toward a target and measuring the time it takes for the reflected pulses to return. This fundamental principle enables the creation of highly accurate 3D representations of our physical world.

How LiDAR Scanning Works

The scanning process follows a precise sequence that happens millions of times per second:

Step-by-Step Process

  1. Environment Setup → The scanning process begins in the target environment
  2. Laser Emission → The LiDAR sensor emits laser pulses toward a target object
  3. Pulse Reflection → The pulses reflect off the object and return to the sensor
  4. Distance Calculation → The sensor calculates the time taken for the pulse to travel and determines the 3D coordinates of the point
  5. Continuous Scanning → This process loops millions of times to collect all necessary points
  6. Data Recording → The sensor records and stores these points in a .las file
  7. Metadata Addition → Additional information (timestamps, sensor position, scanning settings, etc.) is added to the .las file
  8. File Output → The final .las file is generated

LIDAR Capturing Sequence Diagram

Point Cloud Data Structure

In the context of LAS files, LiDAR sensors capture multiple returns per pulse. This capability is crucial for understanding complex environments where laser pulses might reflect off multiple surfaces (like tree branches and the ground beneath).

Each captured point is assigned several key attributes:

  • X, Y, Z coordinates - Precise spatial position
  • Intensity - Strength of the reflected signal
  • Classification - Type of object (ground, vegetation, building, etc.)
  • Return number - Whether it’s the first, second, or last return from a pulse

All of these attributes are essential for creating accurate digital representations of real-world objects.

Types of LiDAR Sensors

LiDAR sensors come in different types, each optimized for specific applications and environments:

🚁 Airborne LiDAR

  • Mounting: Drones and aircraft
  • Best for: Large-scale topographic mapping and flood modeling
  • Coverage: Wide area scanning from above

🏗️ Terrestrial LiDAR

  • Mounting: Tripods or stationary platforms
  • Best for: High-resolution ground-level scans
  • Coverage: Detailed local area mapping

🚗 Mobile LiDAR

  • Mounting: Moving vehicles (cars, trains)
  • Best for: Rapid 3D mapping of linear infrastructure
  • Applications: Roads, railways, and urban corridors

🌊 Bathymetric LiDAR

  • Technology: Green wavelength lasers that penetrate water
  • Best for: Underwater terrain mapping
  • Applications: Coastal regions and shallow water bodies

⚡ Solid-State LiDAR

  • Design: Compact, mechanically simple alternative
  • Best for: Real-time object detection
  • Applications: Electric vehicles and autonomous systems

Choosing the Right LiDAR

The selection of LiDAR type depends on several key factors:

  • Level of detail required
  • Scale of the project
  • Minimum capture time constraints
  • Environmental conditions
  • Budget considerations

Each type offers unique advantages, making them suitable for different applications ranging from large-scale geological surveys to precision automotive navigation.

Thank you for reading! Understanding these fundamentals will help you make informed decisions about LiDAR technology for your specific applications.