LiDar (Light Detection and Ranging)

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Context

According to a Report by Market Research Future (MRFR) LiDAR Market could thrive at a rate of 22.10% between 2022 and 2030.

LiDAR

LiDAR, which stands for Light Detection and Ranging, is a remote sensing method used for measuring the exact distance of an object on the earth’s surface.

The Technology

LiDAR uses a pulsed laser to calculate an object’s variable distances from the earth surface.
These light pulses—combined with other data recorded by the airborne system — generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.

Components of Lidar

A LiDAR instrument principally consists of a laser, a scanner, and a specialized GPS receiver.
Other elements that play a vital role in the data collection and analysis are the photodetector and optics. Most government and private organizations use helicopters, drones and airplanes for acquiring LiDAR data.

Types of LiDAR Systems

LiDAR systems are divided into two types based on its functionality — Airborne LiDAR & Terrestrial LiDAR.

Airborne LiDAR

Airborne LiDAR is installed on a helicopter or drone for collecting data.
As soon as it’s activated, Airborne LiDAR emits light towards the ground surface, which returns to the sensor immediately after hitting the object, giving an exact measurement of its distance. Airborne LiDAR is further divided into two types — Topological LiDAR and Bathymetric LiDAR.
Topographic lidar typically uses a near-infrared laser to map the land, while bathymetric lidar uses water-penetrating green light to also measure seafloor and riverbed elevations.

Terrestrial LiDAR

Unlike Airborne, Terrestrial LiDAR systems are installed on moving vehicles or tripods on the earth surface for collecting accurate data points.
These are quite common for observing highways, analysing infrastructure or even collecting point clouds from the inside and outside of buildings. Terrestrial LiDAR systems have two types — Mobile LiDAR and Static LiDAR.

How does LiDAR Work?

LiDAR follows a simple principle — throw laser light at an object on the earth surface and calculate the time it takes to return to the LiDAR source.
Given the speed at which the light travels (approximately 186,000 miles per second), the process of measuring the exact distance through LiDAR appears to be incredibly fast. However, it’s very technical. The formula that analysts use to arrive at the precise distance of the object is as follows:
The distance of the object=(Speed of Light x Time of Flight)/ 2

Developmental Objectives

LiDAR can be used to accomplish many developmental objectives, some of which are:

Oceanography

When the authorities want to know the exact depth of the ocean’s surface to locate any object in the case of a maritime accident or for research purposes, they use LiDAR technology to accomplish their mission.
Other than locating objects, LiDAR is also used for calculating phytoplankton fluorescence and biomass in the ocean surface, which otherwise is very challenging.

Digital Elevation or Terrain Model

Terrain elevations play a crucial role during the construction of roads, large buildings and bridges.
LiDAR technology has x, y and z coordinates, which makes it incredibly easy to produce the 3D representation of elevations to ensure that concerned parties can draw necessary conclusions more easily.

Agriculture & Archaeology

Typical applications of LiDAR technology in the agriculture sector include analysis of yield rates, crop scouting and seed dispersions. Besides this, it is also used for campaign planning, mapping under the forest canopy, and more.
Apart from the applications mentioned above, LiDAR is used by geoscientists for unearthing geomorphology related secrets, as well as by military for carrying out various security operations near the national borders.

Atmospheric Physics

LIDAR is used to measure the density of clouds and concentration of oxygen, Co2, nitrogen, sulfur and other gas particles in the middle and upper atmosphere.

Military

LIDAR has always been used by the military people to understand the border surrounding land. It creates a high-resolution map for the military purpose.

Meteorology

LIDAR has been used for the study of the cloud and its behavior. LIDAR uses its wavelength to strike small particles in the cloud to understand cloud density.

River Survey

Greenlight (532 nm) Lasar of the LIDAR is used to measure underwater information is required to understand the depth, width of the river, flow strength and more.
For the river engineering, its cross-section data are extracted from Light Detection And Ranging data (DEM) to create a river model, which will create a flood fringe map.

Micro-Topography

Light Detection And Ranging is very accurate and clear-cut technology, which uses Laser pulse to strike the object. Regular Photogrammetry or other survey technology cannot give the surface elevation value of forest canopy. But the LIDAR can penetrate through the object and detect the surface value.

PRACTICE QUESTION

Q. LiDAR, which stands for Light Detection and Ranging – is a remote sensing method used for which of the following purposes?

1.For calculating phytoplankton fluorescence and biomass in the ocean surface.

2.Analysis of yield rates in the agriculture sector.

3.To measure the density of clouds and concentration of oxygen in the atmosphere.

4.To understand the depth, and width of the river and its flow strength.

(a) 1 and 3 only

(b) 2 and 4 only

(d) All of the above.

Correct Answer: (d) All of the above.