LiDAR Technology A Seminar Presentation Submitted in partial fulfillment for the award of Degree of Bachelor of Technology in Electronics and Communication Engineering Submitted toDr. Deepak Bhatia Dr. Sapna Gupta Dept. of Electronics Engineering Submitted byRAHUL YADAV 20EUCEC052 Electronics and Communication Engineering Submitted toDepartment of Electronics Engineering University College of Engineering, Rajasthan Technical University, Kota 21 April, 2023 Introduction to LiDAR Technology BY Rahul Yadav CONTENTS: • Introduction • • • • History Components of LIDAR System Basic Working Principle LIDAR Platforms • Types of LIDAR • Applications • Advantages/Disadvantages • Conclusion Introduction • Acronym for Light Detection And Ranging (sometimes Light Imaging, Detection, And Ranging). • The LASER system, employed for monitoring the nature of environment is called LIDAR. • It is an active remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light. Similar to RADAR, but uses laser light pulses instead of radio waves. • LIDAR uses ultraviolet rays, visible rays and near infrared rays to image object. • By illuminating the target using laser beam a 3-D point cloud of the target and it's surrounding can be generated. Three types of information can be obtained: I. Range to target (Topographic LIDAR, or Laser Altimetry) II. Chemical properties of target (Differential Absorption LIDAR) III. Velocity of target (Doppler LIDAR) WHY LIDAR? • It is used for generating precise and directly georeferenced spatial information. • Lasers produce a coherent light source. • It is Active sensor, do not require sunlight, they can be used either during the day or at night. • LIDAR is popularly used as a technology used to make high resolution maps. HISTORY OF LIDAR: • In the 1930s first attempts were made to measure air density profiles in the upper atmosphere by determining the scattering intensity from searchlight beams. • LIDAR originated in the early 1960s, shortly after the invention of the laser. • combined laser-focused imaging with the ability to calculate distances by measuring the time for a signal to return using appropriate sensors and data acquisition electronics. • 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. • 1995- First commercial airborne LIDAR systems developed. Components of LIDAR System: • Laser Frequency: 50,000 (50k) to 200,000 (200k) pulses per second (Hz) (slower for bathymetry) • Wavelength: Infrared (1500-2000 nm) for meteorology Near-infrared (1040-1060 nm) for terrestrial mapping Blue-green (500-600 nm) for bathymetry LIDAR Transceiver- Generates laser beam and captures laser energy scattered/reflected from target. • Scanner- A laser scanner has three sub-components: the opto mechanical scanner, the ranging unit, and the control processing unit Components of LIDAR System: • POS(IMU & GPS)- Measures "sensor" position and orientation, Inertial measurement systems also contain accelerometers to measure the velocity. • Operator - Permits operator interaction (control/monitor) with system. • Data storage - Captures all AIRBORNE system data required for generation of x, y, z "target" coordinates. • Computer-Integrates/controls interaction of all of the above. Components of LIDAR System: Working Principle • Laser generates an optical pulse. • Pulse is transmitted, reflected and returned to the receiver. • This return beam/pulse is collected and processed to obtain property of target. • Receiver accurately measures the travel time. • X,Y,Z coordinates can be computed from – 1. Laser range – 2. Laser scan angle – 3. Absolute location of sensor Working Principle Calculate Distance: Distance=(Speed of light * Time of Flight)/2 Working Principle LIDAR Platforms • AERIAL/AVIATION(Airborne) For highly detailed, local elevation data - Small area where high density is needed • SATELLITE(space borne) covers large areas with less detail • TERRESTRIAL(ground spaced) AERIAL/AVIATION Platform • Used for topographic mapping and engineering application.It has 3 sub parts: Laser scanning Fixed wing platform Rotary wing platform SATELLITE(space borne): • Mapping of remote areas for scientific purpose. • It has 3 sub parts: Geostationary Polar Sun synchronous TERRESTRIAL(ground spaced): • Produce detailed 3D models of buildings, bridges, streetscapes, factories and other man-made infrastructure. • It has 3 sub types Short range Medium range Long range Bathymetric Mapping System: • Bathymetry is the study of underwater depth of lake or ocean floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. • It uses blue-green laser that can penetrate water and provide returns of underwater objects or bottom. • Effective collection of near shore bathymetry. Types of LIDAR: • ELASTIC LIDAR -Elastic backscatter LIDAR -Mie scattering -Rayleigh scattering • INELASTIC LIDAR -Raman LIDAR -Differential absorption LIDAR(DIAL) -Doppler LIDAR Applications: • Agriculture: Create a Topographical map of the fields and reveals the slopes and sun exposure of the farm land. • Autonomous vehicles: Autonomous vehices obstacle detection and avoidance use LIDAR for to navigate safely through environments. • Geology and soil science: ICE Sat (Ice, Cloud, and land Elevation Satellite). • Law enforcement: LIDAR speed guns • Surveying, Transport, wind farm optimization and many more. • Atmospheric Remote Sensing and Meteorology. Present Technical Advancement in LIDAR: LIDAR speed gunA 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. Google driverless carGoogle's robotic cars have about $150,000 in equipment including a $70,000 LIDAR (light radar) 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. Google Driverless Car Advantages of LIDAR • 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 photogrammetric, GPS or land surveying. • Weather/Light independence Data collection independent of sun inclination and at night and slightly bad weather. • Higher data density Up to 167,000 pulses per second. More than 24 points per Square meter can be measured. Multiple returns to collect data in 3D. DISADVANTAGE • Inability to penetrate very dense canopy leads to elevation model error. • Ineffective during heavy rain. • High operational cost. Future Potential: Despite its limitations, LiDAR has a significant potential for growth in the future. The development of solid-state lasers and other advances in technology have made LiDAR systems smaller, lighter, and more affordable, making it more accessible to a broader range of users. The integration of LiDAR with other sensors, such as cameras and radar, has also increased its usefulness in a range of applications. Conclusion • LIDAR mapping is a maturing technology in our country, and applications are still being identified and developed as end-users begin to work with the data. There are on-going initiatives to identify areas where the technology allows value-added products to be generated or where it offers significant cost reductions over traditional survey methods. • LIDAR is unobtrusive and environmentally friendly, Unlike ground survey techniques. Airbome LIDAR can be flown over areas where access is limited, impossible, or undesirable.
