lidar introduction @ #dataweekend
DESCRIPTION
https://registrano.com/events/dataweekend-07/TRANSCRIPT
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LIDAR技術與應用介紹 © LIDAR Tech. Co.,Ltd., 2013
LiDAR技術與應用介紹
徐偉城
2013-10-05
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LIDAR技術與應用介紹 © LIDAR Tech. Co.,Ltd., 2013
Mapping
• Surface(ground, water) -> Airborne -> Spaceborne
• Sketch -> Analog -> Digital
• Digital Map
– Vector(Google Map地圖)
– Raster(Google Map衛星)
– 3D (Google Earth)
– …
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Elevations on Map
• Features(point, line, polygon)
– Color, Shadow, …
• Contour
• DTM(Digital Terrain Model, Digital Topography Model)
– DEM(Digital Elevation Model)
– DSM(Digital Surface Model)
– DBM(Digital Building Model)
– …
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DTM for Digital Map
• DTM Quality
– Resolution(grid size)
– Precision
– Efficiency
• Methods of DTM
– Ground survey
– Stereo Image processing(Photogrammetry, Satellite)
– Synthetic Aperture Radar(SAR)
– LiDAR
• Airborne LiDAR provides high quality DTM
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DEM Comparison 5
5m grid 1m grid
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What is LiDAR
• LiDAR(Light Detection And Ranging, Lidar, 光達)
– Laser
– Range Finder
– Scanner
• Various type of LiDAR(Laser Scanner)
– Handheld: 3D Scanner
– Desk:3D Scanner & Printer
– Ground:Terrestrial LiDAR
– Mobile Mapping System(car, ship, …)
– UAV & Airborne LiDAR
– Satellite LiDAR
– *Atmosphere LiDAR
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LiDAR on Different Platforms
• Ground
• Car
• Ship
• UAV
• Airborne
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GPS Satellite GPS Satellite
GPS X
Z
Y
IMU
Roll
Heading
Pitch
GPS Base Station
EDMI
Aircraft position
(lat , lon , el)
GPS
Aircraft orientation
(roll , pitch , heading)
IMU
Range and angle
EDMI +
=
(E , N , h …)
Point cloud
Components of Airborne LiDAR
POS(position and
orientaion system)
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Airborne LiDAR Characteristics
• Dense Point
– 1 pt/m2 to 10pt/m2 (sometimes higher)
– Multiple Returns with Intensities
– Full Waveform
• Accurate
– Penetrate Vegetation
– Vertical:5~15cm
– Horizontal:15~50cm (depend on fly height)
• High Efficiency
– High efficiency of data acquisition and processing
– Fewer GCPs
– Filtering without measuring
• Standard Data Format
– Las file (by ASPRS)
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Different Point Density
density=10 pts/m2
density=1 pts/m2 density=2 pts/m2
density=5 pts/m2
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Data Acquisition
Trajectory
Strip adjustment
Aerial Photo
Combined Separation Satellite Lock/Elevation
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Ground Points Filtering
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Automatic classify and manual editing
Correct
Error (canopy)
Error (mountain ridge)
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Flight lines Intensity Classes
Echos Elevation Waveform
Attributes of Point Cloud
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DEM/DSM Products
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DEM
DSM
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DEM/DSM Products
DSM shaded relief DEM shaded relief
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Laser Footprint
Start Pulse
Range and Intensity Measurement
Range 1
Range 2
Range 3
Intensity 1
Intensity 3
Intensity 2
Discrete & Full Waveform LiDAR
LiDAR Returns(Leica, 2004,2010)
Full Waveform Digitizer
T1 , I1
Tn , In
• Laser – Wave length:1064 nm
– Power:2~4 watt
– Beam Divergence:0.25 ~0.8 mrad
– Pulse Rate:50~200 kHz
– Classification:Class IV
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Advantages of Full Waveform LiDAR
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Discrete Las Full Waveform Las
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空載光達產製數值高程模型技術介紹
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About LIDAR Technology Co. Ltd.
• Earth Observations
Spaceborne, Airborne & Terrestrial Data Acquisition
– Photogrammetry and LiDAR
– Hyper-spectrum and Thermal Image
• Geo-informations
Value-added products and applications
– Image Mapping and Interpretation
– Various DEM/DSM Products (90m, 30m, 10m, 5m, 1m, 0.1m)
– Historical Image and Topography Services
• Location Based Services
RS/GIS/GPS Development & Consultant Service
– 3D Building Model
– Disaster Applications
– Augmented Reality
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Thank you
TEL: 886-3-6589495
MAIL: [email protected]
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