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APPLICATIONS OF LIDAR TECHNOLOGY

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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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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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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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Applications

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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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Lidar view of Agricultural Land

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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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Autonomous Vehicle

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ILLUSTRATION

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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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LiDAR Technology Reveals Faults

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NASA ICESat

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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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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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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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Reflectors placed on the Moon

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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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Digital Elevation Model

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Aerial Scanning Terrestrial Scanning

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Case StudyMOLA

• 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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MOLA topographic images of the two hemispheres of Mars

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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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References

• http://www.lidar-uk.com/• http://lidar.cr.usgs.gov/• www.nasa.gov/centers/langley/news/factshe

ets/LITE.html• http://www.webcitation.org/6H82i1Gfx

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