LiDAR technology
- 1. LiDARTechnology P r e s e n t a t i o n Applied Electronics
- 2. TREY research AboutUs 2 Applied Electronics GroupMembers Shlok Doshi (GL) Prathamesh Durgule Aditya Chandanshive Divyesh Burande GR.No- 11910482 GR.No- 11910723 GR.No- 11910312 GR.No- 11910926 Guided by: Prof. Shlipa M Lambor Department : Instrumentation and Control Engineering Division : A Batch : B2
- 3. TREY research Outline Light detection and ranging (LiDAR) Introduction History General Description Principle Architecture Components Types Concepts Working Applications Advantages Limitations Future Developments 3 Applied Electronics
- 4. TREY research Introduction 4 Light detection and ranging (LiDAR) • Lidar is a method for measuring distances (ranging) by illuminating the target with laser light and measuring the reflection with a sensor. • It has terrestrial, airborne, and mobile applications. • Lidar is commonly used to make high-resolution maps, with applications in surveying, geodesy, geomatics etc. Applied Electronics
- 5. TREY research History 5 Light detection and ranging (LiDAR) • Lidar's first applications came in meteorology, where the National Center for Atmospheric Research used it to measure clouds and pollution. • The general public became aware of the accuracy and usefulness of lidar systems in 1971 during the Apollo 15 mission. • In mid-1980s, the lack of reliable commercial global positioning system/inertial measurement unit (GPS/IMU) solutions for sensor positioning presented bottlenecks for further development. • By the mid-1990s, manufacturers of laser scanners were delivering LiDAR sensors that were capable of 2,000 to 25,000 pulses per second to customers who intended to use them for topographic mapping applications. • The scientific uses of LiDAR have continued to evolve. Applied Electronics
- 6. TREY research Generaldescription 6 • 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. • A narrow laser beam can map physical features with very high resolutions. Light detection and ranging (LiDAR) Applied Electronics
- 7. TREY research 7 Applied Electronics BasicPrinciple Light detection and ranging (LiDAR) • The Lidar instrument fires rapid pulses of laser light at a surface, some at up to 150,000 pulses per second. • A sensor on the instrument measures the amount of time it takes for each pulse to bounce back. • Light moves at a constant and known speed so the Lidar instrument can calculate the distance between itself and the target with high accuracy. • By repeating this in quick succession the instrument builds up a complex 'map' of the surface it is measuring. Fig 1.1 Principle of range measurement using laser.
- 8. TREY research 8 Applied Electronics Architecture Light detection and ranging (LiDAR) Fig 3.1 Architecture.
- 9. TREY research 9 Applied Electronics Components Light detection and ranging (LiDAR) Lasers • Lasers are categorized by their wavelength. • 600-1000nm lasers are more commonly used for non- scientific purposes. • Lasers with a wavelength of 1550nm are used for longer range and lower accuracy purposes. Scanners and Optics • Image development speed is affected by the speed at which they are scanned. • Optic choices affect the angular resolution and range that can be detected. • A hole mirror or a beam splitter are options to collect a return signal.
- 10. TREY research 10 Applied Electronics Components Light detection and ranging (LiDAR) Photodetector and Receiver Electronics • The photodetector is the device that reads and records the signal being returned to the system. • There are two main types of photodetector technologies, solid state detectors, such as silicon avalanche photodiodes and photomultipliers. Navigation and positioning systems • it is necessary to determine the absolute position and the orientation of the Lidar sensor to retain useable data. • Global Positioning Systems provide accurate geographical information regarding the position of the sensor. • Inertial Measurement Unit (IMU) records the precise orientation of the sensor at that location. • These two devices provide the method for translating sensor data into static points for use in a variety of systems.
- 11. TREY research 11 Applied Electronics Global Positioning System • Global positioning system, gives the location of the instrument that's holding the LIDAR sensor. • GPS-lidar fusion technique implements method for efficiently modeling lidar-based position error covariance based on features in the point cloud. Inertial Measurement Unit • An IMU is used to determine the attitude of the aircraft as the sensor is taking measurements. • These are recorded in degrees to an extremely high accuracy in all three dimensions. • The laser beam's exit geometry is calculated relative to the Earth's surface coordinates to a very high accuracy. ComponentsEmphasized Light detection and ranging (LiDAR)
- 12. TREY research 12 Applied Electronics Based on orientation: • Lidar can be oriented to nadir, zenith and lateral. • For example, lidar altimeters look down, an atmospheric lidar looks up etc. Based on Illumination Method: Flash LiDAR: • In flash lidar, the entire field of view is illuminated with a wide diverging laser beam in a single pulse. Scanning LiDAR: • Light is sequentially emitted in each direction and the corresponding echoes are detected one by one by the detector. Types Light detection and ranging (LiDAR)
- 13. TREY research 13 Applied Electronics Based on platform: Types Light detection and ranging (LiDAR) Terrestrial • Terrestrial applications of lidar happen on the Earth's surface and can be either stationary or mobile. • Stationary terrestrial scanning is most common as a survey method, for example in conventional topography, monitoring, cultural heritage documentation and forensics. Airborne • Airborne lidar is when a laser scanner, while attached to an aircraft during flight, creates a 3-D point cloud model of the landscape. • This is currently the most detailed and accurate method of creating digital elevation models, replacing photogrammetry. Airborne Bathymetric • Bathymetric LIDAR systems have been specifically developed to measure water depth.
- 14. TREY research 14 Applied Electronics Airborne Light detection and ranging (LiDAR) • The airborne Topographical LiDAR system is comprised of three major time-synchronized components: a laser scanner unit, a GPS, and an IMU. • The laser scanner is composed of a laser range finder unit, which is based on time-of-flight distance measurement techniques, and a beam deflection device that creates the desired scanning pattern. • The GPS provides the absolute position of the sensor platform (plat), and the IMU records the angular attitude of the platform • This enables the system to generate the aircraft's absolute position (X, Y, Z) at any given time. Fig 4.1 working of Airborne LiDAR.
- 15. TREY research 15 Applied Electronics Airborne Light detection and ranging (LiDAR) Fig 4.2 LIDAR survey being performed with a Yellowscan LIDAR on the OnyxStar FOX-C8 HD from AltiGator in November 2015, Belgium.
- 16. TREY research 16 Applied Electronics Bathymetric Light detection and ranging (LiDAR) • The airborne bathymetric lidar technological system involves the measurement of time of flight of a signal from a source to its return to the sensor. • It works using a green spectrum (532 nm) laser beam. • Two beams are projected onto a fast-rotating mirror, which creates an array of points. • One of the beams penetrates the water and detects the bottom surface of the water under favorable conditions. • The data obtained shows the full extent of the land surface exposed above the sea floor. • This technique is extremely useful as it will play an important role in the major sea floor mapping program. Fig 4.3 Portion of the seafloor taken using bathymetric LiDAR
- 17. TREY research 17 Applied Electronics Bathymetric Light detection and ranging (LiDAR) Fig 4.4 High-resolution multibeam lidar map showing spectacularly faulted and deformed seafloor geology, in shaded relief and colored by depth. NOAA Ocean Exploration & Research.
- 18. TREY research 18 Applied Electronics Ground-based Light detection and ranging (LiDAR) • Ground-based Lidar systems are very similar, only that an IMU is not required. • the Lidar is usually mounted on a tripod which the Lidar sensor rotates 360 degrees around. • The pulsed laser beam is reflected from objects such as building fronts, lamp posts, vegetation, cars and even people. • The return pulses are recorded and the distance between the sensor and the object is calculated. • The data produced is in a 'point cloud' format, which is a 3- dimensional array of points, each having x, y and z positions relative to a chosen coordinate system. Fig 4.5 Diagram of the instrument’s scanning pattern.
- 19. TREY research 19 Applied Electronics Ground-based Light detection and ranging (LiDAR) Fig 4.6 A ground based lidar system is used to analyze and scan the ancient desert city of Petra in the National Geographic program "Time Scanners" Image Credit: National Geographic.
- 20. TREY research 20 Applied Electronics Point Clouds • Collection of points that represent a 3D shape or feature. • Each point has its own set of X, Y and Z coordinates and in some cases additional attributes. • When many points are brought together, they start to show some interesting qualities of the feature that they represent. • Most often created by methods used in photogrammetry or remote sensing. • The point clouds are saved as .las files for further developments. Concepts Light detection and ranging (LiDAR) Fig 2.1 Point Cloud mapping of a Terrain.
- 21. TREY research 21 Applied Electronics Laser Returns • Laser pulses emitted from a lidar system reflect from objects both on and above the ground surface: vegetation, buildings, bridges, and so on. • Any emitted laser pulse that encounters multiple reflection surfaces as it travels toward the ground is split into as many returns as there are reflective surfaces. • The first returned laser pulse is the most significant return and will be associated with the highest feature in the landscape like a treetop or the top of a building. Concepts Light detection and ranging (LiDAR)
- 22. TREY research 22 Applied Electronics Laser Returns • Multiple returns can detect the elevations of several objects within the laser footprint of an outgoing laser pulse. • The intermediate returns, in general, are used for vegetation structure, and the last return for bare-earth terrain models. Fig 2.2 pulse hitting a thick branch on its way to the ground.
- 23. TREY research Applications 23 Light detection and ranging (LiDAR) • Autonomous Vehicles • Forest Planning and Management • Forest Fire Management • River Survey • Oil and Gas Exploration Applied Electronics
- 24. TREY research 24 Applied Electronics Autonomous Vehicles Light detection and ranging (LiDAR) • Autonomous vehicles may use lidar for obstacle detection and avoidance to navigate safely through environments. • Point cloud output from the lidar sensor provides the necessary data for robot software. • Software determine where potential obstacles exist in the environment and where the robot is in relation to those potential obstacles. • Examples of companies that produce lidar sensors commonly used in vehicle automation are Ouster and Velodyne. Fig 4.7 Cruise Automation self-driving car with five Velodyne LiDAR units on the roof. "There is absolutely a movement afoot to add LIDAR to mainstream automotive vehicles, which is something that you would buy off of a dealership,” -Anand Gopalan, CEO of Velodyne.
- 25. TREY research 25 Applied Electronics Autonomous Vehicles-Working Light detection and ranging (LiDAR) • Continuously rotating LiDAR system sends thousands of laser pulses every second. • These pulses collide with the surrounding objects and reflect. • The resulting light reflections are then used to create a 3D point cloud. • An onboard computer records each laser’s reflection point and translates this rapidly updating point cloud into an animated 3D representation. • 3D representation is created by measuring the speed of light and the distance covered by it. • It helps to determine the vehicle’s position with other surrounding objects. • It helps to command the brakes to slow or stop the vehicle. • When the road ahead is clear, it also allows the vehicle to speed up.
- 26. TREY research 26 Applied Electronics Autonomous Vehicles-Working Light detection and ranging (LiDAR) Fig 4.8 Design of Autonomous vehicle.
- 27. TREY research 27 Applied Electronics Forest Planning and Management Light detection and ranging (LiDAR) • Lidar is widely used in the forest industry to plan and manage. • It is used to measure vertical structure of forest canopy and also used to measure and understand canopy bulk density and canopy base height. • Also used for the measurement of the peak height. • To estimate the root expansion. Fig 4.9 Airborne LiDAR Drone scanning Forest floor.
- 28. TREY research 28 Applied Electronics Forest Planning and Management Light detection and ranging (LiDAR) Fig 4.10 Lidar imaging comparing old-growth forest (right) to a new plantation of trees (left).
- 29. TREY research 29 Applied Electronics Forest Planning and Management Light detection and ranging (LiDAR) Case-Study • Carried out In the Mediterranean coniferous stand of western Greece, located near Gouria, Aetolia-Acarnania village of Greece. • Terrestrial LiDAR was used to measure the DBH(Diameter Breast Height) of trees and tree height. • Using the dense 3D reconstruction, fitting algorithms to automatically compute the Diameter at Breast Height (DBH) at 1.3 meters from the base of the tree. • For the measurement of the tree height, first, the individual tree was segmented from the TLS derived point cloud. • Then, the individual tree was measured using the difference between the two ends of the point cloud.
- 30. TREY research 30 Applied Electronics Forest Planning and Management Light detection and ranging (LiDAR) Fig 4.11 Area of Study.
- 31. TREY research 31 Applied Electronics Forest Planning and Management Light detection and ranging (LiDAR) Fig 4.12 Faro Focus 3D 330. Fig 4.13 Tree Height Computation from TLS point cloud data.
- 32. TREY research 32 Applied Electronics Forest Planning and Management Light detection and ranging (LiDAR) Case-Study • The results were validated using the field measurements of the DBH and Tree Height using a tree caliper held at right angles to the tree trunk at 1.3 m from the base of the tree. • Finally, this research concludes that TLS is highly potential in deriving forest inventory variables (DBH and tree height) and structural characteristics like volume in greater accuracy. • The results confirm that Terrestrial LiDAR can provide a non-destructive, high-resolution and precise determination of forest inventory parameters. • The outcomes will help researchers to better comprehend deviations in the accuracy of forest inventory variable. • The outcomes will additionally boost decision-making in forest management.
- 33. TREY research 33 Applied Electronics Forest Fire Management Light detection and ranging (LiDAR) • Lidar is becoming widely popular in forest fire management. • Fire department is transforming from reactive to proactive fire management. • Lidar image helps to monitor the possible fire area which is called fuel mapping (fire behavior model). Fig 4.14 LiDAR for forest fire study.
- 34. TREY research 34 Applied Electronics River Survey Light detection and ranging (LiDAR) • Underwater information is required to understand depth, flow strength, width of the river and more. • For the river engineering, its cross-section data is extracted from Lidar data (DEM)to create a river model, which will create flood and flood fringe map. • Lidar is used to create high resolution and accurate surface model of the river. • These extracted Lidar information can be used for the 3D simulation for better planning of the structures or buildings on the riverbank. Fig 4.15 Depth map of river using LiDAR.
- 35. TREY research 35 Applied Electronics Oil and Gas Exploration Light detection and ranging (LiDAR) • As Lidar wavelengths are shorter, it can be used to detect molecules content in the atmosphere that has same or bigger wavelength • There is the new technology called DIAL (Differential Absorption LiDAR) which is used to trace amount of gases above the hydrocarbon region. • This tracking helps to find the Oil and Gas deposits. Fig 4.16 An alteration mineral map.
- 36. TREY research Advantages 36 Light detection and ranging (LiDAR) Resolution & Accuracy: LiDAR generates instantaneous, massive amounts of measurements, and can be accurate to a centimeter. Applied Electronics Low Light Performance: LiDAR is unaffected by ambient light variations and performs well in low any light conditions.
- 37. TREY research Advantages 37 Light detection and ranging (LiDAR) 3D Mapping: LiDAR data can be easily converted into 3D maps to interpret the environment Applied Electronics Speed: LiDAR data are direct distance measurements that don’t need to be deciphered or interpreted– thus enabling faster performance and reducing processing requirement.
- 38. TREY research Limitations 38 Light detection and ranging (LiDAR) • It can’t see beyond solid objects. • This is true for any system that relies on a signal travelling in a straight line. • If the unit is obscured by anything in close range, a lot of data is lost. • Adverse weather conditions or clashing signals from another LiDAR unit could also interfere with the infrared signals. Applied Electronics
- 39. TREY research FutureDevelopments 39 Shrinking LiDAR • LIDAR needs to be much smaller to see widespread use. • In order to accomplish that, Voyant Photonics is ditching the mechanical movement altogether. • They use silicon photonics to sweep the laser without using mechanical parts at all. • Silicon photonics is the study and use of light in silicon. • It’s still a relatively new field, and most research is going into the use light on chips in place of conventional electrical connections. • In this case, Voyant Photonics is using silicon photonics “optical phased arrays” to direct the laser beam across the scene without moving parts. • The result is a LIDAR chip that is in orders of magnitude smaller than existing modules. Applied Electronics
- 40. TREY research 40 Applied Electronics FutureDevelopments Light detection and ranging (LiDAR) Fig 5.1 New Developing LiDAR.
- 42. TREY research References 42 Applied Electronics • Airborne laser scanning: basic relations and formulas, E.P. Baltsavias , ISPRS Journal of Photogrammetry & Remote Sensing 54 1999 199–214. • A Guide to LIDAR Data Acquisition and Processing for the Forests of the Pacific Northwest, Demetrios Gatziolis and Hans-Erik Andersen, Pacific Northwest Research Station, General Technical Report,PNW-GTR-768 July 2008. • Lidar Systems and Data Processing Techniques,Mark Hansen and Peter Howd.