ANALYSIS OF AIRBORNE LASER-SCANNING SYSTEM

121 Pages·2003·2.11 MB·English

ANALYSIS OF AIRBORNE LASER-SCANNING SYSTEM CONFIGURATIONS
FOR DETECTING AIRPORT OBSTRUCTIONS

By

CHRISTOPHER E. PARRISH

A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2003
Copyright 2003

by

Christopher E. Parrish
To Deborah
ACKNOWLEDGMENTS
I wish to express my gratitude to Dr. Grady Tuell, chair of my supervisory
committee, for his significant contributions to this thesis and his continued guidance and
support. I thank Drs. Bill Carter and Ramesh Shrestha for serving on my committee and
for their helpful advice and input.
In addition, I am indebted to the following people who assisted me in various
aspects of this work: Jim Lucas, Dr. Brent Smith, Michael Sartori, Dr. Ramu
Ramaswamy, and Stu Kuper. The following members of the data collection team deserve
thanks and recognition for their hard work: Bill Gutelius, Bill Kalbfleisch, Warwick
Hadley, and Butch Miller.
I thank Captain Jon Bailey and Steve Matula at the National Geodetic Survey for
providing me the opportunity to attend graduate school. Finally, I thank Tom Accardi
and Fred Anderson at the Federal Aviation Administration, Aviation System Standards
for funding the data collection for this research.

iv
TABLE OF CONTENTS
page

ACKNOWLEDGMENTS.................................................................................................iv
LIST OF TABLES............................................................................................................vii
LIST OF FIGURES...........................................................................................................ix
ABSTRACT......................................................................................................................xii
CHAPTER
1 INTRODUCTION........................................................................................................1
Airport Obstruction Surveying.....................................................................................1
Airborne Laser Scanning..............................................................................................5
Background and Motivation.........................................................................................8
Organization of this Work..........................................................................................11

2 THEORY AND PREDICTIONS...............................................................................13
Laser Equation............................................................................................................13
Geometric Considerations in Obstruction Detection..................................................14
Radiometric Considerations in Obstruction Detection...............................................22

3 EXPERIMENTS.........................................................................................................27
Airborne Laser Data Collection..................................................................................27
Calibration..................................................................................................................30
Data Processing..........................................................................................................31
Field Spectrometer Data Collection............................................................................32

4 DATA ANALYSIS....................................................................................................36
Preliminary Analysis..................................................................................................36
Obstruction Detection Analysis..................................................................................42
Automated Obstruction Detection Analysis...............................................................44
Visual Analysis...........................................................................................................50
Analysis of Return Signal Strength Calculations.......................................................52
v
5 CONCLUSIONS AND RECOMMENDATIONS.....................................................56
APPENDIX
A DERIVATION OF RANGE EQUATION .................................................................61
B REFLECTANCE SPECTRA FOR OBSTRUCTIONS AND OTHER OBJECTS
WITHIN THE SURVEY AREAS..............................................................................65
C PHOTOGRAPHS OF FIELD-SURVEYED OBSTRUCTIONS...............................71
D OUTPUT OF AUTOMATED OBSTRUCTION DETECTION ANALYSIS
SOFTWARE...............................................................................................................79
Configuration 1...........................................................................................................79
Configuration 2...........................................................................................................80
Configuration 3...........................................................................................................82
Configuration 4...........................................................................................................84
Configuration 5...........................................................................................................86
Configuration 6...........................................................................................................87
Configuration 7...........................................................................................................89
Configuration 8...........................................................................................................91
Configuration 9...........................................................................................................93
Configuration 10.........................................................................................................94
Configuration 11.........................................................................................................96
Configuration 12.........................................................................................................98
Configuration 13.......................................................................................................100
Configuration 14.......................................................................................................101

LIST OF REFERENCES.................................................................................................104
BIOGRAPHICAL SKETCH...........................................................................................108

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LIST OF TABLES
Table page

2-1 Narrow and wide beam divergences for the system used in this study, based on
three different definitions of beam diameter............................................................19
3-1 The 14 data collection configurations used in this study and the predicted vertical
and horizontal point spacing for each......................................................................27
3-2 Reflectance values at 1064 nm for field-surveyed obstructions and other objects
in the survey areas....................................................................................................34
3-3 Reflectance values at 1064 nm for three horizontal surfaces in Survey Zone 1......35
4-1 Results of testing the airborne laser data sets using an independent data set of
NGS kinematic GPS runway points.........................................................................37
4-2 Percent of obstructions detected in each airborne laser data set and the RMS
difference in elevation between the field-surveyed points and “matching” laser
points........................................................................................................................47
4-3 Analysis of return signal strength calculations for SPN 452...................................53
4-4 Analysis of return signal strength calculations for SPN 449...................................54
4-5 Analysis of return signal strength calculations for SPN 454...................................54
D-1 Tilt: 0; Div: N; FH:750.............................................................................................79
D-2 Tilt: 0; Div: W; FH: 750...........................................................................................80
D-3 Tilt: 10; Div: N; FH: 750..........................................................................................82
D-4 Tilt: 10; Div: W; FH: 750.........................................................................................84
D-5 Tilt: 20; Div: N; FH: 750..........................................................................................86
D-6 Tilt: 20; Div: W; FH: 1050.......................................................................................87
D-7 Tilt: 20; Div: W; FH: 1150.......................................................................................89
D-8 Tilt: 20; Div: W; FH: 750.........................................................................................91
vii
D-9 Tilt: 20; Div: W; FH: 850.........................................................................................93
D-10 Tilt: 20; Div: W; FH: 950.........................................................................................94
D-11 Tilt: 30; Div: N; FH: 750..........................................................................................96
D-12 Tilt: 30; Div: W; FH: 750.........................................................................................98
D-13 Tilt: 40; Div: N; FH: 750........................................................................................100
D-14 Tilt: 40; Div: W; FH: 750.......................................................................................101

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LIST OF FIGURES
Figure page

1-1 Federal Aviation Regulation (FAR) Part 77 obstruction identification surfaces
(OIS)...........................................................................................................................2
1-2 Airborne laser scanning systems produced by the two leading commercial
manufacturers.............................................................................................................5
1-3 Simplified illustration of airborne laser scanning principles.....................................6
1-4 Growth in commercial use of airborne laser scanners from 1995 to 2000................8
1-5 Results of comparing the three airborne laser data sets collected during the 2001
study against field-surveyed obstruction data..........................................................10
2-1 Vertical Point Spacing..............................................................................................15
2-2 Plot of vertical point spacing versus tilt angle based on the following settings:
v = 55 m/s and τ = 0.019 sec....................................................................................16
2-3 Calculation of vertical footprint diameter, A ..........................................................17
v
2-4 Illustration of vertical point spacing (VPS) and effective vertical spacing (EVS)..18
2-5 Profile of laser beam for the University of Florida airborne laser scanning system
and a fitted gaussian.................................................................................................19
2-6 Effective vertical spacing versus tilt angle based on the following parameters:
H = 750 m, v = 55 m/s, τ = 0.019 s, and γ = 0.60 mrad...........................................20
2-7 Definition of horizontal point spacing (HPS)..........................................................21
2-8 Schematic Illustration of the detection and measurement system............................23
2-9 Received power vs. tilt angle...................................................................................25
3-1 Survey project areas overlaid on a digital orthophoto and USGS quadrangles.......28
3-2 Variable-tilt sensor mount designed for this study...................................................29
ix
3-3 Obtaining reflectance measurements for a guywire of one of the towers in Survey
Zone 1 using the ASD LabSpec Pro portable spectrometer.....................................33
4-1 Plot of average elevation bias for each tilt angle setting on the ordinate vs. tilt
angle on the abscissa................................................................................................38
4-2 Average elevation bias vs. tilt angle and propagated systematic error in the
elevation of a laser point..........................................................................................40
4-3 NGS field survey of obstructions at GNV...............................................................43
4-4 Obstruction detection analysis algorithm.................................................................45
4-5 Visual obstruction analysis............................. .........................................................51
4-6 Photograph of SPN 460, and data points on this object based on laser returns
obtained using configurations 5, 8, and 12...............................................................51
4-7 A potentially more rigorous method of performing the return signal strength
computations involving modeling the interaction of the incident laser radiation
with a target as a convolution...................................................................................55
B-1 Reflectance spectra for SPN 445 – strobe lighted tower, a guywire for the strobe
lighted tower, and SPN 446 – tower........................................................................65
B-2 Reflectance spectra for SPN 449 – pole, SPN 452 – antenna, and SPN 453 –
transmission pole......................................................................................................66
B-3 Reflectance spectra for SPN 454 – flagpole, SPN 456 – pole, and a pine tree........67
B-4 Reflectance spectra for a palm tree, a pole, and a generator....................................68
B-5 Reflectance spectra for grass, concrete, and asphalt................................................69
C-1 Photographs of SPN 414 – tree, and SPN 415 – tree...............................................71
C-2 Photographs of SPN 418 – tree, and SPN 431 – obstruction light on pole..............72
C-3 Photographs of SPN 446 – tower, SPN 445 – antenna on strobe lighted tower,
and SPN 448 – antenna on strobe lighted tower......................................................73
C-4 Photographs of SPN 449 – pole, SPN 453 – transmission pole, and
SPN 452 – antenna...................................................................................................74
C-5 Photographs of SPN 454 – flagpole, SPN 456 – pole, SPN 455 – sign, and
SPN 457 – transmission pole...................................................................................75
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