INTRODUCTION TO LIDAR TECHNOLOGY

Basics Of LIDAR Technology

• Acronym Light Detection And Ranging.

• It is a Remote Sensing technology that measure the distance by

illuminating the target with Laser and analysing the reflected light.

• Lidar uses ultraviolet, visible, or near infrared light to image objects.

• It can target a wide range of materials, including non-metallic objects,

rocks, rain, chemical compounds, aerosols, clouds and even

single molecules.

Basics Of LIDAR Technology

• A narrow laser-beam can map physical features with very

high resolution.

• Its wavelength vary to suit the target: from about 10 micro-meters to

the Ultra Violet Radiation of 250 nm.

• In LIDAR, Light is reflected via back-scattering.

• Different types of scattering are used for different lidar applications:

most commonly Rayleigh scattering, Mie scattering, Raman scattering,

and fluorescence.

Working Principle

Basic Formula For Range Measurement

Working Principle

Topographic LiDAR

BASIC COMPONENT

Global Positioning System (GPS)

Inertial Navigation System (INS)

LASER SYSTEM

And Unmanned Aerial Vehicle

Topographic Lidar is used to

make high resolution digital

map of land surfaces.

Multiple Return LiDAR

GENERAL LIDAR EQUATION

Lidar equation is the fundamental equation in laser remote sensing

field to relate the received photon counts (or light power) with the

transmitted laser photon counts (or laser power), light propagation in

background atmosphere, physical interaction between light and objects,

and lidar system efficiency and geometry, etc.

Application

• Agriculture : Create a Topographical map of

the fields and reveals the slopes and sun

exposure of the farm land.

• Archaeology:

• Autonomous vehicles: Autonomous vehicles

use lidar for obstacle detection and avoidance

to navigate safely through environments.

• Biology and conservation

• Geology and soil science: ICESat (Ice,

Cloud, and land Elevation Satellite)

• Atmospheric Remote Sensing and

Meteorology

• Law enforcement: Lidar speed guns

• Military

• Physics and astronomy, Robotics and

Spaceflight

• Surveying, Transport , wind farm

optimization and many more.

Present Technical Advancement in LIDAR

LIDAR speed gun

A LiDAR speed gun is a device used by the police for speed limit enforcement which

uses LiDAR to detect the speed of a vehicle. Unlike Radar speed guns, which rely

on Doppler shifts to measure the speed of a vehicle, these devices allow a police officer

to measure the speed of an individual vehicle within a stream of traffic.

Present Technical Advancement in LIDAR

LITE: Measuring the Atmosphere With Laser Precision

LITE (Lidar In-Space Technology Experiment) was space shuttle

mission from NASA which orbited the Earth while positioned inside the

payload bay of Space Shuttle Discovery. During this nine-day mission,

LITE measured the Earth's cloud cover and track various kind of

particles in the atmosphere. Designed and built at the NASA Langley

Research Center, LITE is the first use of a lidar (light detection and

ranging) system for atmospheric studies from space.

Present Technical Advancement in LIDAR

Google driverless car

Google's robotic cars have about $150,000 in

equipment including a $70,000 lidar (light

radar) system. The range finder mounted on the

top is a Velodyne 64-beam laser. This laser

allows the vehicle to generate a detailed 3D map

of its environment. The car then takes these

generated maps and combines them with high-

resolution maps of the world, producing

different types of data models that allow it to

drive itself.

Present Technical Advancement in LIDAR

Lunar Laser Ranging

experiment

The ongoing Lunar Laser Ranging

Experiment measures the distance between

the Earth and the Moon using laser

ranging. Lasers on Earth are aimed at retro

reflectors planted on the Moon during the Apollo

program (11, 14, and 15), and the time for the

reflected light to return is determined.

Present Technical Advancement in LIDAR

Autonomous cruise control

system

Autonomous cruise control (also called adaptive

or radar cruise control) is an optional cruise

control system for road vehicles that

automatically adjusts the vehicle speed to

maintain a safe distance from vehicles ahead. It

makes no use of satellite or roadside

infrastructures nor of any cooperative support

from other vehicles. Hence control is imposed

based on sensor information from on-

board sensors only.

Present Technical Advancement in LIDAR

ICESat (Ice, Cloud, and land Elevation

Satellite)

It is a part of NASA's Earth Observing System,

was a satellite mission for measuring ice sheet

mass balance, cloud and aerosol heights, as well

as land topography and vegetation

characteristics. ICESat was launched 13

January 2003 on a Delta II rocket

from Vandenberg Air Force Base in California

into a near-circular, near-polar orbit with an

altitude of approximately 600 km. It operated

for seven years before being retired in February

2010, after its scientific payload shut down and

scientists were unable to restart it.

Advantage of LiDAR Technology

Higher accuracy

Fast acquisition and processing

Acquisition of 1000 km2 in 12 hours.

DEM generation of 1000 km2 in 24 hours.

Minimum human dependence

As most of the processes are automatic unlike

photogrammetry, GPS or land surveying.

Weather/Light independence

Data collection independent of sun inclination and at night

and slightly bad weather.

Canopy penetration

LiDAR pulses can reach beneath the canopy thus

generating measurements of points there unlike

photogrammetry.

Higher data density

Up to 167,000 pulses per second. More than 24 points per

m2 can be measured.

Multiple returns to collect data in 3D.

Additional data

LiDAR also observes the amplitude of back scatter energy

thus recording a reflectance value for each data

point. This data, though poor spectrally, can be used for

classification, as at the wavelength used some features

may be discriminated accurately.

Cost

Is has been found by comparative studies that LiDAR

data is cheaper in many applications. This is particularly

considering the speed, accuracy and density of data.

References

• http://sisko.colorado.edu/NOTES/Lecture11.pdf

• http://geography.tamu.edu/class/aklein/geog361/lecture_notes.html

• http://home.iitk.ac.in/~blohani/LiDARSchool2008/Downloads/Kanpur-Baltsavias.pdf

• http://en.wikipedia.org/wiki/Lidar

• http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=1689630&url=http%3A%2F%

2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D1689630

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