Optical RADAR

1. Course: Optical RADAR
LiDAR
Course Coordinator: Arpan Deyasi
1/27/2021 1
Arpan Deyasi, RCCIIT, India

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Arpan Deyasi, RCCIIT, India
What is LiDAR?
uses optical remote sensing technology to measure the
distance of a target by illuminating it with light
use LASER pulse for measuring distance
electromagnetic (EM) waves of ultraviolet, visible or
infrared wavelengths are used
Light Detection And Ranging

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Arpan Deyasi, RCCIIT, India
Information obtained by LiDAR
Range to target (Topographic LiDAR)
Chemical properties of target (Differential Absorption LiDAR)
Velocity of target (Doppler LiDAR)

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Arpan Deyasi, RCCIIT, India
LiDAR platforms
[i] aerial --- for highly detailed, local elevation data
[ii] satellite --- covers large areas with less detail

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Arpan Deyasi, RCCIIT, India
LiDAR Operational Theory
 A pulse of light is emitted and the precise time is
recorded
 The reflection of that pulse is detected and the precise
time is recorded
 Using the constant speed of light, the delay can be
converted into a “slant range” distance
 Knowing the position and orientation of the sensor,
XYZ coordinate of the reflective surface can be
calculated

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Arpan Deyasi, RCCIIT, India
Components of a LiDAR system
 Laser scanner
 High-precision clock
 GPS
 IMU – Inertial navigation measurement unit
 Data storage and management systems

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Arpan Deyasi, RCCIIT, India
Components of a LiDAR system - Laser
Wavelength
infrared (1500 – 2000 nm) for meteorology – Doppler LiDAR
near-infrared (1040 - 1060 nm) for terrestrial mapping
blue-green (500 – 600 nm) for bathymetry
ultraviolet (250 nm) for meteorology
eye-safe; low wattage (<1w)

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Arpan Deyasi, RCCIIT, India
Components of a LiDAR system – Laser Scanner
mirror spins or scans to
project laser pulses to the
surface
scanning angles up to 75
degrees --- scanner measures
the angle at which each pulse
was fired
receives reflected pulse from
surface (“return”)

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Arpan Deyasi, RCCIIT, India
Components of a LiDAR system - GPS
records the x,y,z location of the scanner
surveyed ground base stations in the flight area

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Arpan Deyasi, RCCIIT, India
measures the angular orientation of the scanner
relative to the ground (pitch, roll, yaw)
Components of a LiDAR system - IMU

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Arpan Deyasi, RCCIIT, India
records the time the laser pulse leaves and returns
to the scanner
Components of a LiDAR system - clock

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Arpan Deyasi, RCCIIT, India
Advantages of LiDAR
Higher accuracy
Fast acquisition and processing
Minimum human dependence
Weather/Light independence
Higher data density