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A Seminar On
LIDAR
Submitted to:
Dr. S.K. Katiyar
Presented By :
Rahul Bhagore
Semester 2nd
Scholar No :192111805
Civil engineering department
Manit Bhopal (M.P)

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CONTENT
 Introduction
 General description
 Brief history
 LIDAR platforms
 Types of LIDAR
 Basic Principle and techniques
 How LIDAR works
 LIDAR components
 Some example of LIDAR uses
 Applications
 Advantage
 Disadvantage
 Future Scope
 Conclusion

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INTRODUCTION
LIDAR is an acronym for Light Detection And Ranging.
It is an optical remote sensing technology that can
measure the distance to or other properties of a target by illuminating the
target with light pulse to form an image.

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LIDAR Setup

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General Description
 This is an active remote sensing technique similar to RADAR but uses laser
light pulses instead of radio waves.
 Most LIDAR systems operate in near infrared range of electromagnetic
spectrum (i.e. 1064 nm).
 LIDAR instruments can rapidly measure the earth’s surface at sampling rates
greater than 150 kHz. The resulting product is a densely spaced network of
highly accurate geo-referenced elevation points/point cloud. It can be used to
generate 3-D representation of earth surface.

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History
 Searchlights were used to measure the altitude of clouds.
Measurement was done by pointing a beam of light in sky and then
reading the angle at which the beam light stuck the cloud. On a device
that was a known distance away from the search light one was then
able to obtain height by triangulation.
 First laser based searchlight was constructed by G.Fiocco at MIT using
a ruby laser. From there the development of LIDAR sky rocketed.

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LIDAR Platform
 Airborne topographic LIDAR systems are most common LIDAR
systems. The combination of an airborne platform and a scanning
LIDAR sensor is an effective and efficient technique for collection of
elevation data across tens to thousands of square miles.
 LIDAR was first developed as a fixed position ground based
instrument for studies of atmospheric composition, structure, clouds
and aerosols. Modern navigation and positioning system enable use of
water-based and land based mobile platforms to collect LIDAR data.
Airborne LIDAR data are obtained by mounting a system inside an
aircraft and flying over targeted areas.

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Types of LIDAR
There are two basic types of LIDAR-
 Airborne LIDAR
 Terrestrial LIDAR
Reference : Epri – Electrical power institute
Reference : Topcon website

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Airborne LIDAR
Airborne Lidar : With airborne LIDAR, the system is installed in either a fixed-wing
aircraft or helicopter. The infrared laser light is emitted toward the ground and returned to
the moving airborne LIDAR sensor.
There are two types of airborne sensors:
• Topographic LIDAR
• Bathymetric LIDAR

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Topographic IMAGE
Topographic LIDAR :Topographic LIDAR can be used to derive surface models for use in
many applications, such as forestry, hydrology, geomorphology, urban planning, landscape
ecology, coastal engineering, survey assessments, and volumetric calculations.
Reference : https://thumbs.gfycat.com/

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Bathymetric LIDAR
Bathymetric LIDAR is a type of airborne acquisition that is water penetrating. Most
bathymetric LIDAR systems collect elevation and water depth simultaneously, which
provides an airborne LIDAR survey of the land water interface.
With a bathymetric LIDAR survey, the infrared light (traditional laser system)
is reflected back to the aircraft from the land and water surface, while the additional
green laser travels through the water column. Analyses of the two distinct pulses are
used to establish water depths and shoreline elevations.
Bathymetric information is very important near coastlines, in harbours, and near
shores and banks. Bathymetric information is also used to locate objects on the ocean
floor.
Reference : https://www.giminternational.com

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Terrestrial LIDAR
Terrestrial LIDAR collects very dense and highly accurate points, which allows precise
identification of objects. These dense point clouds can be used to manage facilities, conduct
highway and rail surveys, and even create 3D city models for exterior and interior spaces, to
name a few examples.
There are two main types of terrestrial LIDAR:
• Mobile LIDAR
• Static LIDAR

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Mobile LIDAR
• Mobile LIDAR is the collection of LIDAR point clouds from a moving
platform. Mobile LIDAR systems can include any number of LIDAR sensors
mounted on a moving vehicle. These systems can be mounted on vehicles,
trains, and even boats.
• Mobile systems typically consist of a LIDAR sensor, cameras, GPS (Global
Positioning System), and an INS (inertial navigation system), just as with
airborne LIDAR systems . Mobile LIDAR data can be used to analyze road
infrastructure and locate encroaching overhead wires, light poles, and road signs
near roadways or rail lines.

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Mobile LIDAR
Reference : https://gfycat.com/ancientdarlingamericanbadger

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Static LIDAR
• Static LIDAR is the collection of
LIDAR point clouds from a static
location. Typically, the LIDAR sensor
is mounted on a tripod mount and is a
fully portable laser-based ranging and
imaging system.
• These systems can collect LIDAR
point clouds inside buildings as well as
exteriors. Common applications for
this type of LIDAR are engineering,
mining, surveying, and archaeology.
Reference : MakeAGIF.com

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Basic Principles and Techniques
The basic idea is fairly straight forward-
 Laser generates an optical pulse.
 Pulse is reflected off an object and returns to the system receiver.
 High-speed counter measures the time of flight from the start pulse to
the return pulse.
 Time measurement is converted to a distance (i.e. the distance to the
target and the position of airplane is then used to determine the deviation
and location).

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How LIDAR works
 Laser produces optical pulse.
 Pulse is transmitted, reflected & returned to the
receiver.
 Receivers accurately measure the travel time.
 X,Y,Z ground coordinate can be calculated using :
1. Laser range
2. Laser scan angle
3. Laser position from GPS
4. Laser orientation form INS.

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LIDAR Components
LIDAR has four components:
 Laser.
 Scanner and optics.
 LIDAR sensor and photo detectors.
 Position and navigation systems.

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Laser and scanneroptics
Airborne LIDAR systems use
1064nm diode pumped YAG
lasers while bathymetric systems
use 53 nm double diode pumped
YAG lasers.
The speed at which images can
be developed is affected by the
speed at which it can be scanned
into the system. Moreover,optic
choice affects the angular
resolution and range that can be
detected.

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Laser and scanneroptics
• The HDL-64E LIDAR sensor is designed for obstacle
detection and navigation of autonomous ground vehicles
and marine vessels. It’s durability, 360 field views and very
high data rate makes this sensor ideal for 3D mobile data
collection and mapping applications.
• Two main photo detector technologies are used in
LIDARS:
1. Solid state photo detectors(e.g.:- silicon avalanche
photodiodes).
2. Photomultipliers.

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Position and Navigation System
When a LIDAR sensor is mounted on a
mobile platform such as airplanes or
automobiles, it is necessary to determine
the absolute position and orientation of the
sensor to retain usable data. For this, we
have two techniques:
• GPS(Global Positioning System)
• IMU(Inertial Measurement Unit)

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LIDAR use examples

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LIDAR use examples

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LIDAR use examples

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LIDAR use examples

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New growth area of Application
A Lidar has following applications:
• Agriculture
• Wildlife and conservation
• Wind farm optimization
• Law enforcement

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LIDAR can be used to help farmers determine
which
areas of their fields to apply costly fertilizer to achieve
highest crop yield.
It can create a topographical map of the fields and
reveals the slopes and sun exposure of the farm land.
Agriculture

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Biology and Conservation
 LIDAR has also found many applications in forestry.
Canopy heights, biomass measurements & leaf area
can all be studied using LIDAR systems.
 It is also used by many industries, including Energy,
Railroad & the Department of Transportation as a
faster way of surveying. Topographic maps can also be
generated readily from LIDAR.

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Wind farm optimization
 LIDAR can be used to increase the energy output from
wind farms by accurately measuring wind speeds and
wind turbulence.
 An experimental LIDAR is mounted on a wind
turbulence rotor to measure oncoming horizontal
winds, and proactively adjust blades to protect
components and increase power.

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Law enforcement
 LIDAR speed guns are used by the
police to measure the speed of vehicles for
speed limit enforcement purposes.

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Advantage
The other methods of topographic data collection are land surveying, GPS, interferometry &
photogrammetry. LIDAR technology has some advantages in comparison to these methods
listed below:
 Higher Accuracy
 Fast Acquisition and Processing
 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 meter sq.
can be measured in multiple returns to collect data in 3D.
• Cost- It has been found by comparative studies that LIDAR data is cheaper in many
applications. This is particularly considering the speed, accuracy & density of data.

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Disadvantage
 High operation costs (Rs. 10 Lacs /hour).
 Ineffective during heavy rain and/or low
cloud/mist.
 Degraded at high sun angles and reflections.
 Latency data not processed locally.
 Unreliable for water depth(<2m) &
breaking/turbulent
waves.
 Lack of foliage/vegetation penetration.
 Precise alignment must be maintained.

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Conclusion
LIDAR has become an established method for collecting
very dense & elevation data landscapes, LIDAR can
provide high degree of accuracy & more detailed
information about the landscape than RADAR
technologies.

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Reference
 An Introduction to Lidar Technology, Data, and Applications by National Oceanic and Atmospheric
Administration (NOAA) Coastal Services Center
 Wikipedia
 Lidar basics notes by sikkim manipal institiute of technology
 Survey instrument basics by Prasant surveys Website
 Epri and Topcon Website for images

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