2. Introduction
• Light Detection and Ranging
• Lidar (or LiDAR) is a remote sensing technology that
measures distance by illuminating a target with a laser
and analyzing the reflected light.
• Analogous to RADAR, but using a different part of the
electromagnetic spectrum.
• RADAR uses radio waves or microwaves
• LiDAR uses light at or near the visible spectrum (Visible
spectrum occupies 390 nm - 700 nm)
• Aerial mapping LiDAR generally uses 1064 nm Yttrium-
Aluminum-Garnet lasers
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3. History
• Lidar originated in the early 1960s.
• Its first applications came in meteorology, where the
National Center for Atmospheric Research used it to
measure clouds.
• The general public became aware of the accuracy and
usefulness of lidar systems in 1971 during the Apollo 15
mission, when astronauts used a laser altimeter to map the
surface of the moon.
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4. Principle & Working
• LiDAR uses the laser to illuminate a target and then
analyzes the reflection.
• Distance = (Speed of Light x Time of Flight) / 2
• The LiDAR instrument fires rapid pulses of laser light at
a surface, some at up to 150,000 pulses per second.
• Laser light, due to much shorter wavelength is able to
accurately measure much smaller objects, such as
aerosols and cloud particles.
• The narrow laser beam makes it possible to map objects
with a high degree of resolution
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6. Agriculture
• Lidar can create a topographical map of the
fields and reveals the slopes and sun
exposure of the farm land.
• Another application is in crop mapping in
orchards and vineyards.
• It also indicates which areas to apply the
expensive fertilizers to achieve the highest
crop yield.
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8. Autonomous vehicles
• Autonomous vehicles use Lidar for obstacle
detection and avoidance to navigate safely
through environments.
• Lidar sensor provide data for software to
determine where potential obstacles exist in
the environment and where the vehicle is in
relation to those potential obstacles.
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11. Geology and Soil Science
• To detect subtle topographic features such as river
terraces and river channel banks.
• For detecting faults and for measuring uplift.
• Airborne lidar systems monitor glaciers and have
the ability to detect subtle amounts of growth or
decline.
• NASA ICESat, includes a lidar sub-system for this
purpose.
• The detailed terrain modeling allows soil scientists
to see slope changes and landform breaks which
indicate patterns in soil spatial relationships.
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14. Atmospheric Remote Sensing and
Meteorology
• Lidar systems are used to determine cloud
profiles, measuring winds, studying aerosols and
quantifying various atmospheric components.
• Atmospheric lidar remote sensing works in two
ways -
– by measuring backscatter from the atmosphere,
and
– by measuring the scattered reflection off the
ground or other hard surface.
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15. Mining
• The calculation of ore volumes is
accomplished by periodic (monthly)
scanning in areas of ore removal.
• Lidar sensors may also be used for obstacle
detection and avoidance for robotic mining
vehicles.
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17. Spaceflight
and Astronomy
• A worldwide network of observatories uses
lidar to measure the distance to reflectors
placed on the moon.
• Lidar has also been used for atmospheric
studies from space.
• Station keeping of spacecraft.
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19. Surveying
• It can be used to create DEM (digital
elevation models)
• In forests it is able to give the height of the
canopy as well as the ground elevation.
• For Surveying and Civil Engineering the
most important applications are aerial
scanning and terrestrial scanning .
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22. Case Study
MOLA
• Mars Orbiter Laser Altimeter (MOLA)
• Operated in Mars orbit from September 1997 to
November 2006.
• It transmitted infrared laser pulses at a rate of 10
times/sec. , and measured the time of flight to
determine the range of the Mars Global
Surveyor spacecraft to the Martian surface.
• The range measurements resulted in precise
topographic maps of Mars.
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24. Pole-to-Pole view
• Is a pole-to-pole view of Martian topography from the first
MOLA global topographic model.
• The slice runs from the north pole (left) to the south pole (right)
along the 0° longitude line.
• The figure highlights the pole-to-pole slope of 0.036°, such that
the south pole has a higher elevation than the north pole.
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