Analysis of Integrated Sensor Orientation in Aerial Mapping

202 Pages·2005·3.46 MB·English

UCGE Reports
Number 20204

Department of Geomatics Engineering

Analysis of Integrated Sensor Orientation for Aerial
Mapping

(URL: http://www.geomatics.ucalgary.ca/links/GradTheses.html)

by

Alan Wing Lun Ip

January 2005
THE UNIVERSITY OF CALGARY

Analysis of Integrated Sensor Orientation for Aerial Mapping

By

Alan Wing Lun Ip

A THESIS

SUBMITTED TO THE FACULTY OF GRADUATE STUDIES

IN PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR THE DEGREE OF MASTER OF SCIENCE

DEPARTMENT OF GEOMATICS ENGINEERING

CALGARY, ALBERTA

JANUARY, 2005

© ALAN WING LUN IP 2005
ABSTRACT

Integrated multi-sensor systems, with their major progress in terms of sensor resolution,
data rate and operational flexibility, have become a very attractive mapping tool over the
last decade. In the aerial mapping application, for example, exterior orientation parameters
(EO) of the imaging sensors are required. Using the measurements from a Differential
Global Positioning System (DGPS) integrated with an Inertial Measurement Unit (IMU),
the direct determination of the EO parameters can be obtained. This process is referred to as
Direct Georeferencing (DG). On the other hand, conventional Aerial Triangulation (AT)
uses a block of images with well distributed and sufficient number of Ground Control
Points (GCP) for estimating the EO parameters. The DG provides substantial benefits over
AT, which include the ability to map remote and inaccessible areas and significantly
reducing the cost of the overall project, especially for corridor mapping, or orthophoto
generation using existing Digital Elevation Models (DEM). However, the accuracy
achieved when using DG is limited by the accuracy achievable by DGPS, IMU and any
remaining residual camera/boresight/datum calibration errors. Typically these errors can be
as large as 10 cm RMS, which is not sufficient for some large scale mapping applications.
However, by combining the direct EO data in a traditional block adjustment, these errors
can be minimized. This technique is known as Integrated Sensor Orientation (ISO) which
has been promoted for a few years now. ISO has several advantages over traditional AT,
primarily since; the stable geometry provided by direct EO can reduce the number of
required GCP and tie-point to a minimum. At the same time, ISO provides excellent means
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to control the quality of the estimated EO parameters from a DG system. Furthermore,
while ISO can be used to improve direct EO performance, it provides an opportunity to use
less accurate IMU/DGPS navigation systems for projects that have a well structured block
of imagery.

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ACKNOWLEDGEMENTS

I would like to thank my supervisor Dr. Naser El-Sheimy for his guidance, support and
encouragement throughout my research work, and especially for giving me the opportunity
to study at Department of Geomatics Engineering, The University of Calgary.

I would also like to thank Dr. Mohamed M.R. Mostafa, Mr. Joe Hutton, Mr. Greg Lipa and
Dr. Bruno Scherzinger from Applanix Corporation for allowing me to perform the research
in such an advanced industrial environment and for their guidance, comments and for
providing a number of navigation and photogrammetry software packages and datasets for
my research. Dr. Michael A. Chapman is thanked for introducing me to the world of
Geomatics Engineering, giving me a strong motivation to continue my education.

Applanix Corporation, Z/I Imaging Corporation, Leica Geosystems, and BAE Systems are
acknowledged for providing their software license and support which are used for the work
presented here. I would like to acknowledge the following for providing different datasets:
• PhotoScience Inc. for providing the PhotoScience UofK flight data
• PASCO Corporation for providing the PASCO 310 flight data
• Z/Imaging Corporation (Dr. Mostafa Madani) for DMC Alaska and DMC F-Block
flight data
• 3001 Inc. for the flight crew time, and logistics of the DMC F-Block flight data
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• Airborne Sensing Corporation for the flight crew time, and logistics of the Southern
Ontario flight data acquisition

Financial support from my supervisor and the National Science and Engineering Research
Canada (NSERC), University of Calgary and Applanix Corporation are greatly
acknowledged.

Mr. Ng, Mr. Hutton and Dr. Mostafa are thanked for reviewing my thesis draft. The
examination committee members (Dr. El-Sheimy, Dr. A. Habib, Dr. Mostafa and Dr.
Ronsky) are thanked for taking the time to evaluate my thesis draft and for their valuable
comments.

Last but not least, I am very grateful to my parents’ and friends’ support. Teresa’s support
for 8 continuous years throughout my University Studies will always be remembered.
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Remembrance to my Grandmother
(1912 – 2004)

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TABLE OF CONTENTS

ABSTRACT ………………………………………………………………………………..iii
ACKNOWLEDGEMENTS....................................................................................................v
LIST OF FIGURES .........................................................................................................xii
LIST OF TABLES .........................................................................................................xiv
LIST OF SYMBOLS, ABBREVIATIONS, NOMEMCLATURE...................................xvii

CHAPTER ONE: INTRODUCTION....................................................................................1
1.1. Background and Objective.......................................................................................1
1.2. Thesis Outline..........................................................................................................3

CHAPTER TWO: IMAGE GEOREFERENCING FOR AIRBORNE APPLICATIONS.....5
2.1. Background..............................................................................................................5
2.2. Direct Georeferencing, Indirect Georeferencing and Integrated Sensor Orientation
.................................................................................................................................6
2.2.1. Direct vs. Indirect Georeferencing...............................................................7
2.2.2. Integrated Sensor Orientation......................................................................9
2.3. Error Sources in Image Georeferencing................................................................11
2.3.1. Sensor Errors..............................................................................................18
Imaging Sensor....................................................................................18
Global Positioning System (GPS)........................................................21
Inertial Navigation System (IMU).......................................................23
2.3.2. Integration Errors.......................................................................................26
Sensor Placement.................................................................................26
Synchronization...................................................................................27
Filtering Technique..............................................................................28
2.3.3. Calibration Errors......................................................................................30
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Sensor Errors.......................................................................................30
Lever Arm Offset..................................................................................34
Boresight Mis-Alignment.....................................................................36
Sensor Synchronization........................................................................37
IMU Initial Alignment..........................................................................38
2.3.4. Time-Dependent vs. Time Independent Errors..........................................39
Time-Dependent Errors.......................................................................39
Time-Independent Errors.....................................................................45

CHAPTER THREE: QUALITY CONTROL OF DIRECT GEOREFERENCING DATA..
..........................................................................................................52
3.1. The Need for Quality Control................................................................................52
3.2. Methods used for Quality Control.........................................................................53
3.2.1. Quality Control Requirements...................................................................55
3.2.2. Optimizing the Quality Control Process....................................................56
3.2.3. Integration with Photogrammetry Softcopy..............................................62

CHAPTER FOUR: DATA DESCRIPTION....................................................................66
4.1. Imaging Data..........................................................................................................66
4.2. Simulating a Less Accurate Direct Georeferencing Data......................................67
4.2.1. Data Simulation using Monte Carlo Analysis...........................................69
4.3. Film Camera Flights..............................................................................................76
4.3.1. PhotoScience University of Kentucky Flight............................................77
4.3.2. PASCO Toyonaka City Flight Using a POS AV 310................................80
4.4. Large Format Digital Camera Flights....................................................................84
4.4.1. DMC Alaska Flight....................................................................................85
4.4.2. DMC F-Block New Mexico Flight............................................................88
4.5. Medium Format Digital Camera Flight.................................................................89
4.5.1. DSS Ajax Flight.........................................................................................90
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CHAPTER FIVE: DATA RESULTS AND ANALYSIS.....................................................94
5.1. Typical DG Performance.......................................................................................95
5.1.1. DG System Error Budget Analysis............................................................95
5.1.2. DG Performance of Simulated POS AV 310 Data..................................100
PhotoScience UofK (1:6000).............................................................102
DMC Alaska (1:6000 / 0.15m GSD)..................................................103
DSS Ajax (1:20000 / 0.18 GSD)........................................................104
5.2. Quality Controlled DG vs. ISO............................................................................105
5.2.1. Film Camera Flights................................................................................107
PhotoScience UofK Flight.................................................................107
PASCO Toyonaka City Flight............................................................113
5.2.2. Large Format Digital Camera Flights......................................................116
DMC Alaska Flight............................................................................116
DMC F-Block Flight..........................................................................121
5.2.3. Medium Format Digital Camera Flights..................................................124
DSS Ajax Flight.................................................................................124
5.3. Performance of Less Accurate GPS/IMU Data, Simulation vs. Real Data.........130
5.4. Calibration Error and ISO....................................................................................132

CHAPTER SIX: IMPACT OF DIRECT GEOREFERENCING ON MAPPING
PRODUCT............................................................................................140
6.1. Fast DEM Generation and Orthophoto Production.............................................141
6.2. Near Real-time Data for Rapid Response............................................................145

CHAPTER SEVEN: CONCLUSIONS AND RECOMMENDATIONS.........................147
7.1. Conclusions..........................................................................................................147
7.2. Recommendations................................................................................................150
7.2.1. Direct Georeferencing..............................................................................150
7.2.2. Quality Control and Integrated Sensor Orientation.................................151
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