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.

2. Compiled by-
Atul Anand(35)
Nishat Sameer(34)
Vishal Kumar(40)
Tejistha Pradhan(5)
6th Semester
CIVIL ENGINEERING
SIKKIM MANIPAL INSTITIUTE OF TECHNOLOGY

3. Contents
 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

4. 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.

6. 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.

7. BRIEF 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.

8. LIDAR PLATFORMS
 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.

9. TYPES OF LIDAR
There are two basic types of LIDAR-
 Airborne LIDAR
 Terrestrial LIDAR

10. 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

11. 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.

12. 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 harbors, and near
shores and banks. Bathymetric
information is also used to locate objects on the
ocean floor.

13. 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

14. 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.

15. 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.

16. Basic Principles and Techniques
The basic idea is fairly straightforward-
 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).

17. Working of LIDAR-

18. 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.

19. COMPONENTS
LIDAR has four components:
 Laser.
 Scanner and optics.
 LIDAR sensor and photo detectors.
 Position and navigation systems.

20. Laser
Airborne LIDAR systems use
1064nm diode pumped YAG
lasers while bathymetric
systems use 53 nm double
diode pumped YAG lasers.

21. LIDAR Scanner and Optics
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.

22. LIDAR sensors and Photodetectors
 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.

23. 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)

25. Some examples of LIDAR use:

32. Applications
A LIDAR has the following main applications:
 Agriculture
 Biology and Conservation
 Wind farm optimization
 Law enforcement

33. Agriculture
 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.

34. 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.

35. 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.

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

37. Advantages
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.

38.  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.

39. Disadvantages
 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.

40. Future Scope
The LIDAR technology is now planned for a wide range of
applications that can enable NASA's achievements of its
scientific and space exploration goals.
These applications fall into four general categories:
 Earth Science: Long-duration orbiting instruments
providing global monitoring of the atmosphere and land.
 Planetary Science: Orbiting or land-based scientific
instruments providing geological and atmospheric data of
solar system bodies.
 Landing Aid: Sensors providing hazard avoidance,
guidance and navigation data.
 Rendezvous and Docking Aid: Sensors providing
spacecraft bearing, distance and approach velocity.

41. 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.