Abstract

This thesis addresses the topic of three-dimensional (3D) reconstruction of exposed underground utilities using photogrammetric methods. Research on this topic is mainly motivated by the need for improved information on the location of underground utilities and, thus, to provide reliable information for the management of buried assets. In this thesis, a system of photogrammetric software programs is developed for 3D reconstruction of underground utilities. Camera calibration programs are used for computing interior elements and lens distortion coefficients of digital cameras and saving them in a lookup table (LUT). The accuracy of calibrated image coordinates satisfies the photogrammetric processing demand. An automatic image point detection method is proposed and achieved in these programs. External orientation programs are used for calculating exterior elements of the digital images. Based on geographic information system (GIS) and global positioning system (GPS) techniques, a new ground control points (GCPs) collection method is proposed and implemented in these programs. A 3D reconstruction program provides corresponding functions to obtain and edit 3D information of underground utilities. Epipolar lines are employed as an assisting tool that helps operators easily find homologous points from different digital images. The study results indicate that photogrammetric methods for reconstructing 3D information of underground utilities are effective and low cost.

Highlights

  • Using computer-assisted design (CAD) or geographic information system (GIS) technology, underground utility mapping provides a straightforward source of information indicating utility location

  • Camera calibration consists of the following procedures: [1] Establishing a control pattern; [2] Automatic image points detection; [3] Direct linear transformation (DLT); [4] The calculation of lens distortion coefficients and coordinates re-correction; [5] Repeat [3] and [4] until the average error of homologous points is less than the threshold value (e.g. 0 . 1 pixel); (6 ) Save internal parameters and distortion coefficients into a lookup table (LUT)

  • The corresponding results indicate that it is a rigid camera calibration program because the interior and exterior elements computed by this program are stable and mean errors of image coordinates are less than 2 pixels

Read more

Summary

Motivations of the Study

The demand for accurate mapping underground utilities is growing rapidly It involves the systematic location and mapping of buried utilities within a geographic area. Reliable asset management depends heavily on accurate information. Determining the location of buried utilities is one source of information that constitutes good asset management practice (Tulloch and Hu, 2005). Design and construction projects in areas of concentrated underground utilities require precise utility location information to avoid costly delays, conflicts, redesigns, safety hazards and service disruptions. Using computer-assisted design (CAD) or geographic information system (GIS) technology, underground utility mapping provides a straightforward source of information indicating utility location. This thesis is mainly motivated by the need for improved information on the location of underground utilities, to provide reliable information for buried asset management. At the same time, public dollars on infrastructure upgrades will be saved based on the information about the underground utilities

Problem Statement
Objectives of the Study
Thesis Organization
BACKGROUND
Ground Penetrating Radar System Approach
Global Position System Method
Integrated GPS/GPRS Approach
Conventional Surveying Methods
Subsurface Utilities Engineering Approach
Chapter Summary
METHODOLOGY
Introduction
Why Is Camera Calibration Needed?
Establishing a Control Pattern
Automatic Detection of Orientation Points
Calculation of Interior Elements Using Direct Linear Transformation
Calculation of Lens Distortion Coefficients
External Orientation
GCPs Collection
SEXTMAX
CID 330 IIADB 100 AcDbEntity
Space Intersection
Bundle Adjustment
Epipolar Geometry
CASE STUDY OF CAMERA CALIBRATION
Automatic Detection Program
The Detection of Reference Points
Obtaining Accurate Positions Using LSM
The Combination of Reference Points and GCPs
Camera Calibration and Generation of a Look Up Table
A C am era Calibration
Data Processing
Result Analysis
CASE STUDY OF EXTERNAL ORIENTATION AND GCPS COLLECTION
GIS Data Transformation Program
GCPs Collection Program
External Orientation Program
CASE STUDY OF 3D RECONSTRUCTION
Model Management Module
Graphics Editing Module
CONCLUSIONS AND RECOMMENDATIONS
Summary of the Study
Limitations of the Study
Conclusions
Findings
Recommendations for Future Research
Full Text

Published Version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.