An Introduction to Lidar Sensors and
Applications
For ECE 6930
September 18, 2003
By Dr. Robert Pack
Director, USU Center for Advanced Imaging Ladar
[1]
Ladar Basic Operation
Active Laser
Transmitter
(1.06 micron)
Optics
Object
Detector and PCE
NAVAIR Ladar
on T-39
Range Signal
Processor
Amplitude
[2]
Georeferencing Lidar Shots
[3]
Pushbroom Scanning
[4]
Types of Lidar/Ladar
• Atmospheric Lidar (aerosols)
• Terrestrial Lidar/Ladar (land)
• Bathymetric Lidar (water)
• Target Detection Ladar (hard objects)
[5]
Pseudonymns
• Lidar (Light Detection and Ranging)
• LADAR (Laser Detection and Ranging)
• Laser Range Finder (single shot)
• Laser Radar (imaging lidar)
• Laser Altimeter (pulsed but non-
scanning)
• Electronic Distance Meter (EDM) - low
power units for engineering
theodolites
[6]
Lidar Ranging Methods
• Energy Detection (Phase Modulation
and Time-of-Flight)
• Heterodyne Detection (Coherent)
[7]
Heterodyne Detection
Worse for Range Detection
Better for Velocity Determination
More $$$’s
[8]
Energy Detection
Better for Range Detection
Worse for Velocity Determination
Less $$$’s
[9]
Time-of-Flight Determines Distance
Laser Pulses travel 1 ft every nanosecond.
A 10 ns long laser pulse equates to a 10 ft
long rod of transmitted light
Distance to an object is determined by
timing the round-trip travel time to and
from the ground.
At 1000 ft above ground level, it takes
2000 ns or 2 µs for the round trip.
[10]
Target Types
• Soft (Diffuse)
• Hard (Specular)
• Hybrid (Combination of Diffuse & Specular)
• Resolved (target larger than beam footprint)
• Unresolved (target smaller than beam footprint)
[11]
Sensor Comparison
range resolution: ~20 cm (8”) Capability Issue
Real
Beam specific aspect Adverse weather detection Uncertain object aspect and
mmW Mature technology poor angle resolution
(35 GHz, Low cost
94 GHz) Medium/High search rate
Imaging
Infrared High resolution 2D thermal Uncertain thermal signature
(3-5 mm, Mature technology Limited weather, range
8-12 mm) Low cost Limited target detection
Low search rate
0.3 meter 1 meter
All weather, long range Uncertain object aspect and
Synthetic Mature technology inferior spatial resolution
Aperture Medium/High search rate
Radar High/Medium resolution Cost
Overt (CM)
[12]
Sensor Comparison
0.3 meter 1 meter
Capability Issue
SAR All weather, long range Uncertain object aspect and
Mature technology inferior spatial resolution
Medium/High search rate Cost
High/Medium resolution Overt (CM)
High resolution shape for Limited weather, range
identification; insensitive Maturity
Laser to object aspect and
Radar time-of-day,
(~1 µm) High search rate
Multi-function
range reflectance
Adverse weather detection Immature sensor data fusion
High resolution angle, Maturity (sensor fusion)
Dual range Cost
Mode
mmW SAR I2R
[13]
Qualitative Discusison of Lidar System Use
[14]
Simulated Range Images for NAVAIR
range = 2142m
range = 3552m
range = 1432m
range = 1942m
Images created with a USU ladar simulation being used to assess potential ladar image
quality. The cases shown are 100 micro radian resolution from 300m altitude. Targets
include T-72 tank and SCUD TEL at various ranges. [15]
Early Generation Range Image
[16]
Example Range Image
[17]
Example Range Images
“Redeye” (G-Range) Geothermal Tank
LB Ranch LB Buildings
LB Bridge Coso Mountains
[18]
3D Point Cloud
Ground Map of Little Petroglyph Canyon
[19]
3d Surface Reconstruction
Produced by Optech ALTM 1020 Topographic Mapper
[20]
The Flight of a Laser Pulse is Timed to Determine Distance to
Objects
FIRST AND LAST RETURN
RETURN ENERGY
TRAVEL TIME (nsec)
0 CANOPY TOP RETURN
50 HEIGHT = 15 m
100 GROUND RETURN
[21]
Vegetation Characterization using Wide Laser Footprint and
High SNR Waveform Return (NASA VCL)
[22]
Forest Data Acquired from an Aircraft
Produced by Optech ALTM 1020 Topographic Mapper
[23]
High-Resolution Topographic Contours
Produced by Optech ALTM 1020 Topographic Mapper
[24]
Vegetation Removal
Produced by Optech 2050 Bathymetric Mapper
[25]
Vegetation Removal
Produced by Toposys Lidar
[26]
Suspended Wire Detection
[27]
Wire Detections
Produced by Optech ALTM 1020 Topographic Mapper
[28]
Wire Detections
Produced by Optech ALTM 1020 Topographic Mapper
[29]
Wire Detections
Produced by Toposys Lidar
[30]
Wire Modeling from Lidar
Produced by Flimap Lidar
[31]
Penetration Through Shallow Clear Water Provides
Bathymetry
[32]
Example of Bathymetric Mapping
Produced by NASA Bathymetric Mapper
[33]
Bathymetric Mapping
Produced by Optech Shoals Bathymetric Mapper
[34]
Bathymetric Mapping
Produced by Optech Shoals Bathymetric Mapper
[35]
City Modeling
Produced by Toposys Lidar
[36]
Coastal Modeling
Produced by Toposys Lidar
[37]
Enhancements with EO Data
[38]
Lidar Enables:
• Transforming Distorted
Photography...
• Into Corrected
Orthorectified Imagery
[39]
With Orthophotos:
All objects are
precisely
positioned
geographically
and can be used
in a GIS system.
[40]
2½-D Images
Produced by Laserscan, Denver, Colorado
[41]
Infrared 3-D Image of a City
Produced by TopoSys, Stuttgart, Germany
[42]
SDL/USU Lidar Work
• Riegl Lidar System
• Canon Digital Camera
• Custom Camera Head
• Potable Power Supply
• 1000 shots per second
• 400 meter maximum range
[43]
Reigl Scanning Ladar System
Imported from Germany
• 1000 Hz @ 3 mrad divergence
• 400 m maximum range
• Class 3B Diode Laser
[44]
Canon EOS D30 Digital
Camera for Color EO
• Custom Spherical Camera Head
• 2160 x 1440 pixels @ 0.3 mrad
• CMOS Imager
[45]
The instruments are mounted so that they rotate around the
same nodal point. This simulates a common aperture.
[46]
Sample Data Taken in Logan
340m
RANGE IMAGE INTENSITY IMAGE EO IMAGE
[47]
Pixel-Level Data Fusion
340m
EO/LADAR Data Ratio - 100:1
3 mrad range pixels 0.3 mrad EO pixels
[48]
More Sample Data Taken in Logan
240m
RANGE IMAGE INTENSITY IMAGE EO IMAGE
[49]
Pixel-Level Data Fusion
340m
EO/LADAR Data Ratio - 100:1
3 mrad range/intensity pixels 0.3 mrad EO pixels
[50]
Range Image Transformed to Surface in 3D Space
[51]
Digital Imagery Made 3D By Texturing Lidar-
Generated Surface
[52]
Note Tank On Canyon Wall
[53]
3D Image of Canyon Wall Which is a Mosaic of Eight Frames from
One Station
[54]
Perspective Showing Rock Structure
[55]
Perspective Showing Canal & Trail
[56]
Orthophoto (Bird’s Eye View)
[57]
Some Lidar Performance Specs
Manufacturer Pixels/Sec Max. Range Returns/Sec
Navair Build 4 2,560,000* 6000 m 5,120,000*
Navair Build 2 1,000,000 6000 m 1,000,000
TopoSys II 83,000 1600 m 166,000
LH Systems – std 50,000 3000 m 150,000
Optech 2050 50,000 2000 m 100,000
TerraPoint 20,000 3000 m 80,000
Terra Remote 25,000 -- 75,000+
LH Systems – opt 15,000 6000 m 75,000
Optech 3033 33,333 3000 m 66,666
Laseroptronix 50,000 1000 m 50,000
Saab TopEye 6,000 1000 m 30,000
John Chance 10,000 300 m 10,000
[58]
SAAB Topeye Lidar
• Top Eye (SAAB)
> 3D terrain mapping
> Spot scan (5 beam)
Commerical
Commerical LADARs
LADARs in
in production.
production.
[59]
Hellas (EADS) Lidar
Obstacle Avoidance System
Commerical
Commerical LADARs
LADARs in
in production.
production.
[60]
TopoSys Lidar
Commerical
Commerical LADARs
LADARs in
in production.
production.
[61]
Leica ALS Lidar
Commerical
Commerical LADARs
LADARs in
in production.
production.
[62]
Eaglescan Lidar
Commerical
Commerical LADARs
LADARs in
in production.
production.
[63]
Flimap Lidar
Commerical
Commerical LADARs
LADARs in
in production.
production.
[64]
NASA Vegetation Canopy Lidar (VCL)
Research
Research LADARs
LADARs
[65]
NASA MOLA Lidar
Research
Research LADARs
LADARs
[66]
