LiDAR acquisition
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LiDAR acquisition

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pinciples, techniques, differences and usage of LiDAR-acquired data

pinciples, techniques, differences and usage of LiDAR-acquired data

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LiDAR acquisition LiDAR acquisition Presentation Transcript

  • LiDAR Acquisition 1. Introduction 1. 2. 2. Aerial LiDAR 1. 2. 3. 3. Objective and general setup static vs. mobile Registration Bathymetric/Hydrographic LiDAR 1. 2. 5. Objective and general setup Scanning process Characteristic properties – further information Terrestrial LiDAR 1. 2. 3. 4. Laser capturing unit Signals Objectives and general setup Characteristics – further information Atmospheric LiDAR
  • Introduction • LiDAR = Light Detection and Ranging • Laser-based scanning – terrain – bathymetry – atmospheric properties • Collection of point set („point cloud“) data
  • Introduction • Common setup to all scanners: transmitter and detector • Detectors varies between scanners
  • Introduction • signals: pulse-ranging or continuous wave • Both create discrete measurements • Final data: single/multi-return range measurements or (full) waveform Images taken from: Conservation Applications of LiDAR Data, Joel Nelson, University of Minesota; Further information on signals: Airbone laser scanning – an introduction and overview, A. Wehr and U. Lohr, ISPRS Journal of Photogrammetry and Remote Sensing, Volume 54, Number 2, July 1999, pp. 68-82(15) Single-return Mutli-return Waveform return
  • Aerial LiDAR • Objective: – earth observation of large areas (municipalities or bigger) – 2.5D data
  • Aerial LiDAR • Scanning process plane pos. F α Δz s(t) p Δy β
  • Aerial LiDAR • Swath scanning -> line scan pattern Image from: A guide to LiDAR data acquisition and processing for the forest of the Pacific Northwest, D. Gatziolis and H.-E. Andersen, Gen. Tech. Rep. PNW-GTR-768. Portland, Oregon, U.S. Department of Agriculture, 2008
  • Aerial LiDAR • Characteristics and Properties: – – – – – Scanning angle Scanning frequency Pulse length -> vertical resolution Footprint diameter Footprint spacing (non-uniformal horizontal resolution) – Returns per pulse • Beam frequency for topographic scan: 1040 – 1064 nm
  • Aerial LiDAR • further information – continuous wave: “Introduction to continuous-wave Doppler lidar”, C. Slinger and M. Harris, TechReport – full-waveform lidar: “From single-pulse to fullwaveform airborne laser scanners: Potential and Practical Challenges”, W. Wagner et al., Int. Archives of Photogrammertry and Remote Sensing, Vol. 35, No. Part B, 2004, pp. 201-206 – full-waveform lidar: “Empirical Comparison of FullWaveform Lidar Algorithms: Range Extraction and Discrimination Performance”, C.E. Parrish et al., Photogrammetric Engineering & Remote Sensing, Vol. 77, No. 8, August 2011, pp. 825-838
  • Terrestrial LiDAR • capture smaller-scale landscape phenomena in full 3D (steep coast segments, yardrangs) • Time-series captures • 360° capture Image courtesy: Using Terrestrial Light Detection and Ranging (Lidar) Technology for Land-surface Analysis in the Southwest, Soulard, C.E. and Bogle, R.C. and Western Geographic Science Center and Geological Survey (U.S.), Fact Sheet, 2011
  • Terrestrial LiDAR • static LiDAR: fixed position; semi-automatic registration; standard in geological field survey • mobile LiDAR: vehicle-mounted; easier largescale survey; restricted to drivable (urban) regions
  • Terrestrial LiDAR • reference of scans: – aerial & mobile terrestrial LiDAR: semi-automatic – static terrestrial LiDAR demands registration Computer Vision: – control points in view – inertia sensors – shape fitting – image-guided registration Image: Terrestrial laser scanning in geology: data acquisition, processing and accuracy considerations, Buckley, S.J. et al., Journal of the Geological Society, May 2008, Volume 165, pp. 625-
  • Bathymetric LiDAR • Objective: scan shallow water areas (harbor, rivers and deltas) • setup very similar to aerial LiDAR • 2 lasers: 532 nm and 1064 nm Image source: Meeting the Accuracy Challenge in Airborne LiDAR Bathymetry, Guenther, G.C et al., Proceedings of EARSeL-SIG-Workshop LIDAR, 2000
  • Bathymetric LiDAR • further literature: – Meeting the Accuracy Challenge in Airborne LiDAR Bathymetry, Guenther, G.C et al., Proceedings of EARSeL-SIG-Workshop LIDAR, 2000 – Green, waveform lidar in topo-bathy mapping – Principles and Applications, Nayegandhi, A., USGS St. Petersburg/Florida
  • Atmospheric LiDAR • surveying atmospheric properties (temperature, aerosols, etc.) • usually telescope at detector • observable particles and properties depend on beam wavelength (1064 nm or 532 nm) and backscatter type
  • Atmospheric LiDAR Image courtesy of: Xinzhao Chu, CU-Boulder, Lecture “Fundamentals of LiDAR Remote Sensing”, 2011