ABSTRACT
3D as-built models have been utilized over the years as an aid to several engineering activities and there are conventional survey methods; e.g. Total Station ray method, photogrammetric technique etc., with which the data required for these models are generated. These methods have proven not to be optimal in capturing datasets required for the modeling of some complex engineering structures. The reasons for this been the intrusive nature of some of these methods and their point rather than surface sampling abilities.Others include the time taken to generate enough data as required and the average overall low accuracy achievable by these methods. This had led to several 3D models been a product of various degrees of interpolations and its attendance loss in model accuracy. High Definition Surveying (HDS) is a non-intrusive surveying method for collecting timely, accurate and complete geometric data of existing sites and structures.The HDS method has the capability of capturing tens of thousands of surface points in a second, making it very suitable for generating data required for the modeling of complex surfaces and structures. In this project, the ability and suitability of the HDS technique for use in complex and usually volatile oil and gas environments were proven as it was utilized for the production of the 3D model required as an aid for the retrofitting of an offshore gas platform. The Leica ScanStation 2 was deployed for the data capture alongside the Cyclone application program, the Cyclone program was also utilized for the processing of the measured data as well as production of a topologically and geometrically accurate 3D model of the required section of the platform. The produced model was subjected to some physical tests/checks to certify its correctness. Data interoperability was also achieved as the resulting 3D model as well as cloud of points were viewed and analyzed from various application programs e.g. AutoCAD. Further research was however recommended especially in the area of methods of quality assurance of completed models as the physical methods currently been utilized is not only slow, but also gives an indication of the presence of an error without giving an idea of its source and how it can be corrected.
Table of Contents
Approval Page - - - - - - - - - iv
Dedication Page - - - - - - - - - v
Acknowledgement - - - - - - - - - vi
Abstract - - - - - - - - - vii
Table of contents - - - - - - - - - viii
CHAPTER ONE
1.1 Introduction - - - - - - - - - 1
1.2 Research Problem - - - - - - - - - 7
1.3 Significance of the Research - - - - - - - 8
1.4 Aim and Objectives - - - - - - - - 9
1.5 Study Area - - - - - - - - - 9
1.6 Scope - - - - - - - - - 10
CHAPTER TWO
2.1 Theoretical Framework - - - - - - - 11
2.1.1 When can we use HDS? - - - - - - - 12
2.2 History of the Laser-Based Instruments - - - - - 12
2.3 Properties of the Laser - - - - - - - 13
2.3.1 Monochromaticity - - - - - - - 13
2.3.2 Directionality - - - - - - - - 14
2.3.3 Coherence - - - - - - - - 14
2.3.4 Brightness - - - - - - - - 15
2.3.5 Focusing of Laser Beam - - - - - - 15
2.4 Types of Laser - - - - - - - - 15
2.5 Operations of the Terrestrial Laser Scanner - - - - - 16
2.5.1 The Arbitrary or Local Surveys - - - - - 17
2.5.2 The Controlled Survey - - - - - - 18
2.6 Classification of Terrestrial Laser Scanners - - - - - 19
2.6.1 Classification based on the Measurement Principle - - - 20
2.6.1.1 Time of Flight (ToF) or Pulse-Based Scanners - - 20
2.6.1.2 Phase-Shift Measurement Scanners - - - - 22
2.6.1.3 Triangulation Measurement Scanners - - - 23
2.6.2 Classification based on Mode of Data Capture - - - 26
2.6.2.1 Static Laser Scanning - - - - - - 26
2.6.2.2 Dynamic Laser Scanning - - - - - 27
2.6.3 Classification based on the Beam Deflection System of Laser Scanners 27
2.6.3.1 Profiling System - - - - - - 27
2.6.3.2 Imaging System - - - - - - 28
2.6.3.2.1 Camera view - - - - - - 28
2.6.3.2.2 Panoramic view - - - - - - 29
2.7 Software for Data Evaluation - - - - - - - 30
2.7.1 Cyclone - - - - - - - - 31
2.7.1.1 Cyclone Modules - - - - - - 31
2.7.1.2 Cyclone™-SERVER - - - - - - 31
2.7.1.3 Cyclone Databases - - - - - - 32
2.7.1.4 Central Cyclone Server for Efficient Database Management - 32
2.7.2 3D IPSOS - - - - - - - - 32
2.7.2.1 Core Module - - - - - - - 32
2.7.2.2 Consolidation - - - - - - - 33
2.7.2.3 Reconstruction - - - - - - 33
2.7.3 Light Form Modeller - - - - - - - 33
2.7.3.1 LFM Modules - - - - - - 33
2.7.4 Other packages - - - - - - - 34
2.8 Registration - - - - - - - - - 35
2.8.1 Overview of Registration Methods - - - - - 35
2.8.1.1 Marker-based registration methods - - - - 36
2.8.1.2 Sensor-based registration methods - - - - 36
2.8.1.3 Data-driven registration methods - - - - 36
2.8.2 Registration with Control Points - - - - - 36
2.8.3 Registration with the Iterative Closest Point (ICP) Method - - 38
2.8.4 Indirect Registration & Geo-Referencing - - - - 39
2.8.4.1 Target-to-target registration - - - - - 39
2.8.4.2 Cloud-to-cloud registration - - - - - 39
2.8.4.3 Surface-to-surface registration - - - - 40
2.8.5 Direct Registration & Geo-Referencing - - - - 41
2.8.6 General Aspect of Registration and Geo-Referencing - - 41
2.9 Error Sources of Laser Scanning Points - - - - - 42
2.9.1 Scanning Geometry: - - - - - - - 42
2.9.2 Surface Properties: - - - - - - - 43
2.9.3 Instrument Calibration and Properties: - - - - 43
2.9.4 Environmental Conditions: - - - - - - 43
2.10 Safe Applications of the Laser Scanner - - - - - 44
2.10.1 Safety Rules for all Lasers, Regardless of Output Power Level - 47
2.10.2 Non-Beam Hazards Associated with Laser - - - - 48
2.11 Advantages of the Laser Scanning over the conventional techniques - 48
CHAPTER THREE
3.1 Literature Review - - - - - - - - 50
3.2 Drawbacks of the Laser Scanning Techniques - - - - 54
3.3 Laser Scanning in High Risk/Hazardous Environment - - - 57
3.4 Significant Application Gap Addressed - - - - - 58
CHAPTER FOUR
4.1 Methodology - - - - - - - - - 59
4.2 Measurement - - - - - - - - - 59
4.2.1 Survey Planning - - - - - - - 61
4.2.1.1 Determine the Survey Requirements and Understand the Job Specifications - - - - - - 61
4.2.1.2 Reconnaissance and Analysis of the area to be surveyed - 62
4.2.1.3 Determination and Selection of Optimal Scanning Locations 63
4.2.1.4 Choice of Targets, Determination/Selection of Optimal Target Locations, and Placement of Targets - - - - 65
4.2.1.5 Data Management Decisions - - - - - 66
4.2.2 Field Operations - - - - - - - 67
4.2.2.1 Survey Preparation - - - - - - 67
4.2.2.2 Setting up the Scanner - - - - - 68
4.2.2.3 Connecting the Scanner - - - - - 68
4.2.2.4 Scanner Settings - - - - - - 69
4.2.3 Data Acquisition - - - - - - - 70
4.2.3.1 Systematic Scanning of the Required Section of the Platform 70
4.2.3.2 Scanning and Acquisition of targets - - - - 71
4.2.3.3 Completeness Checking - - - - - 72
4.3 Data Processing using Cyclone - - - - - - 72
4.3.1 Data Preparation - - - - - - - 73
4.3.2 Registration and Geo-referencing - - - - - 73
4.3.2.1 Viewing the Cloud of Points Model - - - - 81
4.3.3 Data Filtering - - - - - - - - 82
4.3.4 Clouds Unification - - - - - - - 86
4.4 Modeling - - - - - - - - - 87
4.4.1 Components of the model - - - - - - 88
4.4.2 Production of 3D models or Direct 3D Modeling from Point Cloud 91
4.4.3 Modeling Procedures - - - - - - - 91
4.5 Data Interoperability and Conversion from Cyclone to other Third Party Software 104
4.5.1 Conversion/Export of Point Clouds - - - - - 105
4.5.2 Conversion/Export of 3D models - - - - - 107
CHAPTER FIVE
5.0 Results and Discussions - - - - - - - 108
5.1 Model views in AutoCAD environment - - - - - 109
5.2 Model views in Cyclone Environment - - - - - 111
5.3 Discussions - - - - - - - - - 116
CHAPTER SIX
6.0 Conclusion and Recommendations - - - - - - 118
References - - - - - - - - - - 120