Introduction to lidar and its application

LiDAR acronym as Light Detection and Ranging is remote sensing technology having several technical and socialite advantages. This technology is basically used to make high resolution digital map to provide the real time data. This data can be processed and used to extract the useful information. A typical LIDAR system consists of three main components, a GPS system to provide position information, an INS unit for attitude determination, and a LASER system to provide range (distance) information between the LASER firing point and the ground point. In addition to range data, modern LIDAR systems can capture intensity images over the mapped area. Therefore, LIDAR is being more extensively used in mapping and GIS applications.

1. Introduction to LIDAR Technology

2. Basics Of LIDAR Technology Acronym  Light Detection And Ranging. It is a Remote Sensing technology that measure the distance by illuminating the target with Laser and analysing the reflected light. Lidar uses ultraviolet, visible, or near infrared light to image objects. It can target a wide range of materials, including non-metallic objects, rocks, rain, chemical compounds, aerosols, clouds and even single molecules.

3. Basics Of LIDAR Technology  A narrow laser-beam can map physical features with very high resolution. Its wavelength vary to suit the target: from about 10 micro-meters to the Ultra Violet Radiation of 250  nm. In LIDAR, Light is reflected via back-scattering . Different types of scattering are used for different lidar applications: most commonly Rayleigh scattering, Mie scattering, Raman scattering, and fluorescence. 

4. Working Principle

5. Basic Formula For Range Measurement

6. Working Principle

7. Topographic LiDAR BASIC COMPONENT Global Positioning System (GPS) Inertial Navigation System (INS) LASER SYSTEM And Unmanned Aerial Vehicle Topographic Lidar is used to make high resolution digital map of land surfaces.

8. Multiple Return LiDAR

9. General LIDAR Equation Lidar equation is the fundamental equation in laser remote sensing field to relate the received photon counts (or light power) with the transmitted laser photon counts (or laser power ), light propagation in background atmosphere, physical interaction between light and objects, and lidar system efficiency and geometry, etc.

10. Application Agriculture : Create a Topographical map of the fields and reveals the slopes and sun exposure of the farm land. Archaeology: Autonomous vehicles: Autonomous vehicles use lidar for obstacle detection and avoidance to navigate safely through environments . Biology and conservation Geology and soil science: ICESat ( Ice, Cloud , and land Elevation Satellite ) Atmospheric Remote Sensing and Meteorology Law enforcement: Lidar speed guns Military Physics and astronomy, Robotics and Spaceflight Surveying, Transport , wind farm optimization and many more .

11. 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. Unlike Radar speed guns, which rely on  Doppler shifts to measure the speed of a vehicle, these devices allow a police officer to measure the speed of an individual vehicle within a stream of traffic .

12. Present Technical Advancement in LIDAR LITE: Measuring the Atmosphere With Laser Precision LITE (Lidar In-Space Technology Experiment ) was space shuttle mission from NASA which orbited the Earth while positioned inside the payload bay of Space Shuttle Discovery. During this nine-day mission, LITE measured the Earth's cloud cover and track various kind of particles in the atmosphere. Designed and built at the NASA Langley Research Center, LITE is the first use of a lidar (light detection and ranging) system for atmospheric studies from space.

13. Present Technical Advancement in LIDAR Google driverless car Google's robotic cars have about $150,000 in equipment including a $70,000 lidar ( li ght ra dar ) system. The range finder mounted on the top is a  Velodyne  64-beam laser. This laser allows the vehicle to generate a detailed 3D map of its environment. The car then takes these generated maps and combines them with high-resolution maps of the world, producing different types of data models that allow it to drive itself .

14. Present Technical Advancement in LIDAR Lunar Laser Ranging experiment The ongoing  Lunar Laser Ranging Experiment  measures the distance between the Earth and the  Moon using  laser ranging.  Lasers on Earth are aimed at   retro reflectors  planted on the Moon during the Apollo program (11, 14, and 15), and the time for the reflected light to return is determined.

15. Present Technical Advancement in LIDAR Autonomous cruise control system Autonomous cruise control (also called adaptive or radar cruise control) is an optional  cruise control system for road vehicles that automatically adjusts the vehicle speed to maintain a safe distance from vehicles ahead. It makes no use of satellite or roadside infrastructures  nor of any cooperative support from other vehicles. Hence control is imposed based on sensor information from on-board sensors only. 

16. Present Technical Advancement in LIDAR ICESat  (Ice, Cloud, and land Elevation Satellite) It is a part of NASA's Earth Observing System, was a  satellite mission for measuring ice sheet mass balance, cloud and aerosol heights, as well as land topography and vegetation characteristics. ICESat was launched 13 January 2003 on a Delta II  rocket from  Vandenberg Air Force Base in California into a near-circular, near-polar orbit with an altitude of approximately 600 km. It operated for seven years before being retired in February 2010, after its scientific payload shut down and scientists were unable to restart it.

17. Advantage o f LiDAR Technology   Higher accuracy Fast acquisition and processing Acquisition of 1000 km2 in 12 hours. DEM generation of 1000 km2 in 24 hours. Minimum human dependence As most of the processes are automatic unlike photogrammetry, GPS or land surveying. Weather/Light independence Data collection independent of sun inclination and at night and slightly bad weather.    Canopy penetration LiDAR pulses can reach  beneath the canopy thus generating measurements of points there unlike photogrammetry.    Higher data density  Up to 167,000 pulses per second. More than 24 points per m2 can be measured. Multiple returns to collect data in 3D. Additional data LiDAR also observes the amplitude of back scatter energy thus recording a reflectance value for each data point.  This data, though poor spectrally, can be used for classification, as at the wavelength used some features may be discriminated accurately.    Cost Is has been found by comparative studies that  LiDAR data is cheaper in many applications.  This is particularly considering the speed, accuracy and density of data.   

18. References http:// sisko.colorado.edu/NOTES/Lecture11.pdf http :// geography.tamu.edu/class/aklein/geog361/lecture_notes.html http ://home.iitk.ac.in/~ blohani/LiDARSchool2008/Downloads/Kanpur-Baltsavias.pdf http:// en.wikipedia.org/wiki/Lidar http ://ieeexplore.ieee.org/xpl/login.jsp?tp=& arnumber=1689630&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D1689630

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