LiDaR Remote Sensing

LiDAR Remote Sensing: A Primer

LiDAR (Light Detection and Ranging) is a remote sensing technology that uses light in the form of a pulsed laser beam to measure ranges to the Earth's surface and various objects. This technology is incredibly versatile and has applications in a wide range of fields, including:

Cartography and mapping: Creating highly accurate 3D maps of the Earth's surface, including topography, vegetation, and buildings.
Forestry: Measuring forest height, density, and biomass.
Geology: Studying geological formations and identifying potential natural hazards.
Archaeology: Discovering and mapping ancient sites.
Environmental monitoring: Assessing changes in land cover, coastal erosion, and climate-related impacts.

Key Terminologies and Concepts

Laser: A device that emits an intense beam of coherent light. LiDAR systems use lasers to emit pulses of light.
Pulse: A short burst of laser energy.
Time of Flight: The time it takes for a laser pulse to travel to a target and return to the sensor. This is used to calculate the distance to the target.
Point Cloud: A collection of individual points, each representing a specific location on the Earth's surface. LiDAR data is often processed to create point clouds.
Digital Surface Model (DSM): A 3D representation of the Earth's surface, including the tops of buildings, trees, and other objects.
Digital Terrain Model (DTM): A 3D representation of the Earth's surface, excluding vegetation and other objects.
Intensity: A measure of the strength of the laser return signal. This can be used to infer information about the properties of the target.
Footprint: The area on the ground that is illuminated by a laser pulse.
Accuracy: The degree to which LiDAR measurements agree with true values.
Precision: The degree to which LiDAR measurements are consistent with each other.

Facts and Applications

High Accuracy: LiDAR can provide centimeter-level accuracy in measurements.
Versatility: LiDAR can be used to measure a wide range of objects, from small plants to large buildings.
Penetration: LiDAR can penetrate vegetation and other materials to measure underlying surfaces.
Real-Time Data: Some LiDAR systems can provide real-time data, allowing for immediate analysis and decision-making.

Comments

Natural Disasters

A natural disaster is a catastrophic event caused by natural processes of the Earth that results in significant loss of life, property, and environmental resources. It occurs when a hazard (potentially damaging physical event) interacts with a vulnerable population and leads to disruption of normal life . Key terms: Hazard → A potential natural event (e.g., cyclone, earthquake). Disaster → When the hazard causes widespread damage due to vulnerability. Risk → Probability of harmful consequences from interaction of hazard and vulnerability. Vulnerability → Degree to which a community or system is exposed and unable to cope with the hazard. Resilience → Ability of a system or society to recover from the disaster impact. 👉 Example: An earthquake in an uninhabited desert is a hazard , but not a disaster unless people or infrastructure are affected. Types Natural disasters can be classified into geophysical, hydrological, meteorological, clim...

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...

Trans-Himalayas

1. Location and Extent The Trans-Himalayas , also known as the Tibetan Himalayas , form the northernmost mountain system of India . Stretching in an east–west alignment , they run parallel to the Greater Himalayas , covering: Ladakh (Jammu & Kashmir, UT) Himachal Pradesh (north parts) Tibet (China) They mark the southern boundary of the Tibetan Plateau and act as a transition zone between the Indian Subcontinent and Central Asia . 2. Major Ranges within the Trans-Himalayas Karakoram Range World's second highest peak: K2 (8,611 m) . Contains Siachen Glacier and Baltoro Glacier . Geopolitical importance: forms part of India–Pakistan–China border. Ladakh Range Separates the Indus Valley from the Tibetan Plateau . Known for rugged barren mountains and cold desert conditions. Zanskar Range Lies south of the Ladakh Range, cut deeply by the Zanskar River . Famous for trekking and frozen river expeditions...

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 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...

Vineesh V, Geography

Search This Blog