LIDAR Raaz Dwivedi
B.Tech 16
Kumar Goutam
B.Tech 23
Abhinav Kumar Rastogi
B.Tech 24
MOTIV ATION!
MOTIV ATION!
MOTIV ATION ? – THE FIRST ONE
Thee Th
firs fi rstt per pe r son to measu me asure re the distance to the Moon was the th e 2nd-century-BC astronomer and geographer Hipparchus.. He was Hipparchus approximately 26,000 km off th thee actual distance, an error of ab about out 6.8% 6.8%..
He used simple trigonometry.. trigonometry
MOTIV ATION ? – THE FIRST ONE
Today oday T
we know kn ow,, the actual distance varies distance varies over the cou course rse of the orbi orbitt of the moon moon,, from 356,700 kilometres (221,600 mi) at the perigee and 406,300 kilometres (252,500 mi) at apogee.
How do we gather such accurate information?
SECOND - AN EXCITING ONE !
How
did we figure out that the topography of Mars is something like this ?
Also,
how does a spacecraft ensure that it lands safely on such an unknown terrain ?
THIRD - AN OBVIOUS ONE!
How does this device detect the speed and what is its name?
MOTIV ATION - ENOUGH!
And
many more thunders and wonders!
Lets explore all of them together ….
OVERVIEW
Introduction Why LiDAR ? • Principle • Design and Working • Classifications •
LiDAR in Remote Sensing Meteorology • Terrain Mapping •
Other Applications LiDAR Speed Gun • Military • Archaeology • Geology •
Future News • Auto driving • NASA Project • Country Mapping • In Movies •
LIDAR – MEANING ?
Light
An
Detection And Ranging
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
WHY LIDAR?
We
already have RADAR right?
Why
develop a new technology?
LiDAR has many advantages over RADAR
Though
in some applications RADAR wins!
WHY LIDAR ? Time
to Collect 1 Million Points
Conventional Surveying: 15.5 years
Photogrammetry: 1.5 years
LiDAR : 6.7 seconds @ 150 kHz (Yo !
)
LIDAR VS RADAR
LiDAR needs much higher processing speed and storage capacity as it collects huge data
LiDAR is suited for low level high accuracy surveys
Limitation in navigation accuracy comes due to limitations of the GPS system
MAIN COMPONENTS OF LIDAR
PRINCIPLE ? - SIMPLE !
Similar principle to RADAR – pulses of light emitted into the atmosphere and scattered back by some agents
Light collected by a telescope(receiver)
PRINCIPLE ? - SIMPLE !
Spectrometers or interference filters isolate wavelength concerned Photon-counting or analogue detection
Time-of-flight
gives scattering height
TYPICAL LIDAR EQUATION Transmitted pulse power
Backscatter coefficient of atmosphere
r
P(λ,r) = P0 A E β(λ,r) exp-{ 2 0∫ Σ(λ,r’) dr ’ } r r2 Solid angle subtended by mirror Received power
Efficiency of optics and electronics
Transmittivity of atmosphere: contributions to Σ from scattering by air and aerosols, absorption by gases
LIDAR – GENERAL DESCRIPTION
Use of ultraviolet, visible, or near infrared light i.e. wavelength ranging between 250nm to 10um
Used for a wide range of targets, including non-metallic objects, rocks, rain, chemical compounds, aerosols, clouds and even single molecules.
PULSE MODELS Two
types of pulse models : Micropulse LiDAR system and High Energy system
Micropulse system
Less energy Laser – order of 1 μ J “Eye-Safe” High
Energy system
Common in atmospheric research Measures temperature, pressure, wind etc
HIGH ENERGY SYSTEM Typical
Pulse Energy 10 – 400 mJ
Typical
Repetition Rate 10 – 50 s-1
Typical
Pulse Length 3 ns
Linearly polarised (Usually fixed wavelength – dye lasers and some solid state lasers tuneable)
DETECTION SCHEME Two
kinds of detection schema
Incoherent
i.e. direct energy detection
Principally an Amplitude measurement Coherent
detection (best for Doppler)
Phase sensitive measurement Coherent
system more sensitive than direct, operates at a lower power but requires more complex Transceiver
LIDAR – CLASSIFICATION Based
on looking -
1. Upward looking, eg. to determine aerosol content in air
2. Downward looking, eg. to determine the terrain of the region
3. Horizontal looking, eg. to determine the shape of the near-by buildings
LIDAR – ANOTHER CLASSIFICATION
Based on Back-Scattering
1. Rayleigh LiDAR 2. Mie LiDAR 3. Raman LiDAR (Yo INDIA ) 4. Fluorescence LiDAR
LIDAR IN REMOTE SENSING
FIRST USE IN METEOROLOGY !
The Upper Atmosphere above Antarctica under LiDAR beams
WHAT CAN WE MEASURE WITH LIDAR ?
Clouds Aerosol Water vapour Minor constituents e.g. ozone, hydrocarbons Temperature Wind LiDAR can be used from the ground, aircraft or even from space
USES
Differential Absorption LiDAR (DIAL) – to measure gas content in atmosphere (on line /off line λ ? ) Doppler LiDAR and Rayleigh Doppler LiDAR to measure temperature and/or wind speed eg. NASA's HARLIE LiDAR Olympics – Yacht Racing
LOOKING THROUGH VEGETATION
In densely forested areas, RADAR tends to hit more tree trunks, producing scattering effect.
Commercial systems use Side Looking RADAR .
LiDAR uses a LASER beam pointing straight down. A return is received if there is a hole in the canopy.
ADVANTAGES
Better Height Resolution
Better Time Resolution
Backscattered signals – Ready Interpretation
May be mounted on trailers or aircraft for mobile operation – Easy Operation
DISADVANTAGES
Large data handling capacity needed
Systems
to observe the stratosphere tend to be large and expensive
Precise
alignment must be maintained
OTHER APPLICATIONS
LIDAR SPEED GUN
Device used by the police for speed limit enforcement which uses LiDAR Working?
3D LASER SCANNING
Uses Real-Time 3D imaging and capturing Revolutionized mining industries for mapping underground assets Ideal for historical documentation and/or rehabilitation
MILITARY
NATO report claimed LiDAR to be the – – 2010) application of “ Best option for the near-term (2008 stand-off(?) detection systems from Biological Warfares is Ultraviolet Laser Induced Fluorescence ( UV LIF) ”
Fully Autonomous Flight in June 2010 – Boeing 6
Currently a lot of research investment DARPA (Defence Advanced Research Projects Agency)
GEOLOGY
Mt. St. Helens (2004)
Aircraft-based LiDAR and GPS has evolved into an important tool for detecting faults and for measuring uplift.
Also for studying effects of earthquakes
FUTURE
IN NEWS
India – BMC plans to use it for Land Surveying in Mumbai (Oct 14 , 2012)
28th October 2012, New York Times Headlines: “ Yes, Driverless Cars Know the Way to San Jose! ”
Google’s Auto Driving Car
BRIGHT FUTURE
“
Self Driving Cars is the most important thing that computers are going to do in the next 10 years. ”
And Self Driving is possible because of LiDAR! BRIGHT FUTURE ?
NASA PROJECT
Currently, NASA is developing novel lidar sensors aimed at needs of future planetary landing missions.
These
lidar sensors are a 3-Dimensional Imaging Flash LiDAR, a Doppler LiDAR and a Laser Altimeter.
NASA PROJECT
From over 20 km - Laser Altimeter
From 15 - 10 km - Laser Altimeter / Flash LiDAR
From over 2 km – Doppler LiDAR
From over 1 km – 3D Imaging Flash LiDAR
AWESOME DENMARK !
LIDAR SCANNING FOR MOVIES
ACKNOWLEDGEMENTS Prof.
Girish Kumar
Wikipedia
Prof.
G. Vaughan, University of Manchester, UK
NASA
