Skip to main content

LiDaR Principles and applications

LIDAR, which stands for Light Detection and Ranging, is a remote sensing technology that uses laser light to measure distances and create detailed three-dimensional representations of objects and environments. Here are the fundamental principles of LIDAR remote sensing:


1. Laser Emission: LIDAR systems emit laser pulses towards the target area. These laser pulses are typically in the form of short, intense bursts of light.


2. Propagation of Light: The emitted laser pulses travel through the atmosphere, where they may interact with particles or molecules, experiencing scattering and absorption. The laser light continues until it strikes an object or a surface.


3. Reflection or Scattering: When the laser pulse encounters an object or surface, a portion of the light is reflected back towards the LIDAR sensor. The time it takes for the laser pulse to travel to the target and return is measured.


4. Time-of-Flight Measurement: LIDAR calculates the distance to the target by precisely measuring the time it takes for the laser pulse to travel to the target and back. This is done using the speed of light as a constant.


5. Multiple Measurements: LIDAR systems typically emit thousands or even millions of laser pulses per second and record the return time and intensity of each pulse. This results in a dense cloud of points, often referred to as a "point cloud."


6. Data Processing: The collected data is processed to generate a detailed three-dimensional representation of the target area. This point cloud can be used to create digital elevation models, maps, or 3D models of objects and terrain.


7. Applications: LIDAR remote sensing is used in various applications, including topographic mapping, forestry management, urban planning, archaeology, autonomous vehicles, and more. Its ability to provide precise elevation and object information makes it invaluable for many industries.


LIDAR technology can be implemented in various ways, such as airborne LIDAR using aircraft or UAVs, terrestrial LIDAR for ground-based scanning, and even spaceborne LIDAR for planetary exploration. It has revolutionized the way we collect detailed geospatial information and has numerous practical applications in science, engineering, and environmental monitoring.



1. ICESat-2 (Ice, Cloud, and land Elevation Satellite-2): Launched in 2018 by NASA, ICESat-2 is designed for Earth science research, specifically to measure changes in ice sheet thickness and sea ice freeboard. It uses a LIDAR system called the Advanced Topographic Laser Altimeter System (ATLAS) to collect elevation data.


2. GEDI (Global Ecosystem Dynamics Investigation): Launched as part of the International Space Station (ISS) payload, GEDI is a LIDAR instrument that measures the three-dimensional structure of forests and ecosystems. It provides valuable data for understanding the Earth's carbon cycle.


3. LRO (Lunar Reconnaissance Orbiter): While primarily designed for lunar exploration, NASA's LRO carries a LIDAR instrument called the Lunar Orbiter Laser Altimeter (LOLA). LOLA measures the surface topography of the Moon with high precision.


4. TanDEM-X: This is a German radar satellite mission operated in conjunction with TerraSAR-X. Although it primarily uses radar technology, it also features a bistatic mode that, when combined with TerraSAR-X, can produce a global digital elevation model (DEM) with unprecedented accuracy.


5. ISAT (Indian Satellite for Antarctic Observation): ISAT-1, an Indian remote sensing satellite, was equipped with a LIDAR altimeter. It was used for monitoring ice sheet dynamics and elevation changes in the polar regions.


6. ATLAS (Advanced Topographic Laser Altimeter System): ATLAS is a LIDAR instrument onboard the Earth, Science, and Climate Pathfinder satellite, which is part of NASA's Earth System Science Pathfinder Program. It's used to monitor ice sheet elevation changes.





Comments

Popular posts from this blog

geostationary and sun-synchronous

Orbital characteristics of Remote sensing satellite geostationary and sun-synchronous  Orbits in Remote Sensing Orbit = the path a satellite follows around the Earth. The orbit determines what part of Earth the satellite can see , how often it revisits , and what applications it is good for . Remote sensing satellites mainly use two standard orbits : Geostationary Orbit (GEO) Sun-Synchronous Orbit (SSO)  Geostationary Satellites (GEO) Characteristics Altitude : ~35,786 km above the equator. Period : 24 hours → same as Earth's rotation. Orbit type : Circular, directly above the equator . Appears "stationary" over one fixed point on Earth. Concepts & Terminologies Geosynchronous = orbit period matches Earth's rotation (24h). Geostationary = special type of geosynchronous orbit directly above equator → looks fixed. Continuous coverage : Can monitor the same area all the time. Applications Weather...

Disaster Management

1. Disaster Risk Analysis → Disaster Risk Reduction → Disaster Management Cycle Disaster Risk Analysis is the first step in managing disasters. It involves assessing potential hazards, identifying vulnerable populations, and estimating possible impacts. Once risks are identified, Disaster Risk Reduction (DRR) strategies come into play. DRR aims to reduce risk and enhance resilience through planning, infrastructure development, and policy enforcement. The Disaster Management Cycle then ensures a structured approach by dividing actions into pre-disaster, during-disaster, and post-disaster phases . Example Connection: Imagine a coastal city prone to cyclones: Risk Analysis identifies low-lying areas and weak infrastructure. Risk Reduction includes building seawalls, enforcing strict building codes, and training residents for emergency situations. The Disaster Management Cycle ensures ongoing preparedness, immediate response during a cyclone, and long-term recovery afterw...

Linear Arrays Along-Track Scanners or Pushbroom Scanners

Multispectral Imaging Using Linear Arrays (Along-Track Scanners or Pushbroom Scanners) Multispectral Imaging: As previously defined, this involves capturing images using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation. Linear Array of Detectors (A): This refers to a row of discrete detectors arranged in a straight line. Each detector is responsible for measuring the radiation within a specific wavelength band. Focal Plane (B): This is the plane where the image is formed by the lens system. It is the location where the detectors are placed to capture the focused image. Formed by Lens Systems (C): The lens system is responsible for collecting and focusing the incoming radiation onto the focal plane. It acts like a camera lens, creating a sharp image of the scene. Ground Resolution Cell (D): As previously defined, this is the smallest area on the ground that can be resolved by a remote sensing sensor. In the case of linear array scanne...

Discrete Detectors and Scanning mirrors Across the track scanner Whisk broom scanner.

Multispectral Imaging Using Discrete Detectors and Scanning Mirrors (Across-Track Scanner or Whisk Broom Scanner) Multispectral Imaging:  This technique involves capturing images of the Earth's surface using multiple sensors that are sensitive to different wavelengths of electromagnetic radiation.  This allows for the identification of various features and materials based on their spectral signatures. Discrete Detectors:  These are individual sensors that are arranged in a linear or array configuration.  Each detector is responsible for measuring the radiation within a specific wavelength band. Scanning Mirrors:  These are optical components that are used to deflect the incoming radiation onto the discrete detectors.  By moving the mirrors,  the sensor can scan across the scene,  capturing data from different points. Across-Track Scanner or Whisk Broom Scanner:  This refers to the scanning mechanism where the mirror moves perpendicular to the direction of flight.  This allows for t...

Disaster Risk

Disaster Risk