2. Basic Remote Sensing Technology
Sonar
Radar
Lidar
If we have ever heard
an echo, we’ll be
familiar with the basic
principle behind three
similar technologies
6. Disadvantages of RADAR Technology
Radar can take up to 2
seconds to lock on
Radar has wide beam
spread
Cannot track if deceleration
is greater than one
mph/second
Large targets close to radar
can saturate receiver
Clutter
7. What is LIDAR?
LIDAR (Light Detection
And Ranging, also
LADAR) is an optical
remote sensing
technology that can
measure the distance to,
or other properties of a
target by illuminating the
target with light, often
using pulses from a laser.
11. The term "laser radar"
is sometimes used,
even though LIDAR
does not employ
microwaves or radio
waves and therefore is
not radar in the strict
sense of the word.
.
General Description
12. LIDAR uses ultraviolet,
visible, or infrared light to
image objects and can be
used with a wide range of
targets, including non-
metallic objects, rocks,
rain, chemical compounds.
14. • Water vapour
• Temperature
Lidars can be used from the ground, aircraft
or from space
15. Components used in lidar…
Laser
Scanner and optics
Photodetector and receiver electronics
Position and navigation systems
16. • 600–1000 nm lasers are
most common for non-
scientific applications.
• Better target resolution is
achieved with shorter
pulses, provided the
LIDAR receiver detectors
and electronics have
sufficient bandwidth
Laser
17. • How fast images
can be developed
is also affected by
the speed at
which they are
scanned.
Scanners and optics
18. Optic choices affect the
angular resolution and
range that can be
detected. A hole mirror or
a beam splitter are
options to collect a return
signal .
19. • Two main photodetector
technologies are used in
From atmosphere
Receiver lidars: solid
state photodetectors,
such as silicon avalanche
photodiodes, or
photomultipliers.
Photodetector and receiver electronics
20. • The sensitivity of the
receiver is another
parameter that has to be
balanced in a LIDAR
design.
21. LIDAR sensors that are
mounted on mobile
platforms such as airplanes
or satellites require
instrumentation to
determine the absolute
position and orientation of
the sensor.
Position and navigation systems
22. Such devices generally
include a Global
Positioning System
receiver and an Inertial
Measurement Unit (IMU).
23. • Agriculture- LIDAR also
can be used to help
farmers determine
which areas of their
fields to apply costly
fertilizer to achieve
highest crop yeild.
Applications..
25. Oil & gas
exploration surveys
Engineering
/construction
survey
26. Faster lock-on time ( less
than 1/3 second)
Very narrow beam spread
( less than 6 ft over
2000 ft range)
Better ability to track
decelerating targets
Advantages of LIDAR technology
27. Typically mounted,
and aimed with
optical targeting
device
Fewer sources of
interference
Much more difficult
to detect
28. Disadvantages
• High operating costs (> £10k / 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) and
breaking/turbulent waves
• Lack of foliage/vegetation penetration
• Precise alignment must be maintained
29. Future scope
The lidar technology is now planned for a wide
range of applications that can enable NASA’s
achievement of its scientific and space
exploration goals. These applications fall into
four general categories:
a) Earth Science:
30. b) Planetary Science:
orbiting or land-based
scientific instruments
providing geological
and atmospheric data
of solar system bodies
31. c) Landing Aid: sensors
providing hazard avoidance,
guidance and navigation
data.
d) Rendezvous and Docking
Aid : sensors providing
spacecraft bearing, distance,
and approach velocity .
32. 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.
33. 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.
35. Summary
• Lidar technique allows continuous monitoring
of profiles with good height resolution
• Different scattering mechanisms permit
different kinds of measurement
• New technology offers more compact sources
and development of transportable and
mobile systems