Reconstructed pipes and cables from the Maasvlakte 2 area. Red: electricity cables. Green: telecommunication cables. Blue: water pipes. Yellow: others. The brown ditches correspond to lateral cable space. Utilities data provided by Port Rotterdam, Buildings courtesy of Geemente Rotterdam. Visualization performed using X3DOM. DELFT UNIVERSITYOF TECHNOLOGY MSC THESISIN GEOMATICS Three-dimensional reconstruction of underground utilities for real-time visualization Supervisors: Dr. Sisi ZLATANOVA Author: Dr. Martijn MEIJERS Josafat Isaí GUERRERO IÑIGUEZ Co-reader: Dr. Erik JANSEN September 2012 To my parents: Julio and Alicia. Abstract This research discusses the conversion of underground utilities datasets into scene graph models for its 3D visualization using the WebGL technology, which is a Javascript interface to access the 3D graphics hardware. This conversion requires to reconstruct the volumetric appearance of the objects from its abstract representation, involving several decisions towards its mapping into a scene graph. Each decision taken carries consequences in the rendering performance and given the nature of the underground utilities, multiple problems arise which should be addressed before achieving a fluid visual- ization. This research considers multiple reconstruction approaches and studies the corresponding factors affecting the performance by introducing a testing framework. With the results of the tests, the considered factors are ranked based on their performance and used to give advice towards the best approaches for the reconstruction underground utilities and its applicability to WebGL environments. Acknowledgments I would like to thank all the persons involved in this project, friends and colleagues from all the corners of the world who made this project possible, to whom I owe a big part of my life. First, I express my utmost gratitude towards Sisi, a wonderful woman who gave me the opportunity to work in the MV2 project and showed me the path to a new dimension: the third. I also thank Martijn for its endless patience and timely comments, but specially for having the time to share a few words so needed in desperate times. Thanks also to Erik Jansen for contributing with his knowledge towards the completion of this work. A special mention goes to the people involved in the MV2 project: Anne Jan Boersma, Albert Mul- der and Suzana Kana from Port Rotterdam, Joris Goos from Geemente Rotterdam, Jackob Beetz form TUE, Marian de Vries and Hugo Ledoux from OTB. I also want to say thanks to Elfriede Fendel, who get me into this master program and helped during almost all the process involved with it. A loud mention goes to to Statoil and TU Delft who fully funded my studies, to whom I owe not money but an endless appreciation. In addition, I also want to express my gratitude towards my colleagues: Naresh, Ravi, Daphne, Elise, Pien, Simeon, Hoe Ming, and Wouter, who made this experience something unique. At last but not the least, I also thank my family who helped me along this years, gave me moral support and endless love. Thanks. Josafat ‘Voici mon secret. Il est très simple: on ne voit bien qu’avec le cœur. L’essentiel est invisible pour les yeux.’ Antoine de Saint Exupéry Le Petit Prince CONTENTS 1 Introduction 1 1.1 Motivation . 1 1.2 Technological push . 3 1.3 Objective and Research Questions . 4 1.4 Enclosing project . 5 1.5 Research scope . 6 1.6 Chapters overview . 7 2 Background Information 9 2.1 Related work on underground utilities . 9 2.2 State of the art in 3D visualization for the Web . 10 2.2.1 OpenGL and OpenGL ES . 10 2.2.2 WebGL . 11 2.2.3 WebGL frameworks . 12 2.3 3D Visualization Pipeline . 15 2.4 Rendering pipeline . 17 2.5 Visualization performance issues . 19 3 Reconstruction of underground utilities 21 3.1 General requirements . 21 3.2 Reconstruction flow . 22 3.3 Underground objects . 24 3.3.1 Cables and Pipes . 25 3.3.2 Cables and pipes protection. 25 3.3.3 Free space trace and lateral cable space. 26 3.3.4 Pits and signs . 26 3.4 Reconstruction methods . 26 3.4.1 Split methods . 30 3.4.2 Non-Split methods . 39 4 Reconstruction implementation 45 4.1 Target Frameworks . 45 4.1.1 X3DOM and X3D . 45 4.1.2 JSON and SceneJS . 48 4.2 Scene Assembly . 49 4.2.1 X3DOM . 50 4.2.2 SceneJS . 51 4.3 Complexity analysis . 53 4.3.1 Primitive analysis . 53 4.3.2 Reconstructed objects analysis . 55 4.3.3 Scene analysis . 57 i ii CONTENTS 5 Performance Testing Framework 63 5.1 Terminology................................................. 63 5.2 Performance factors. 64 5.2.1 Factors impact . 66 5.2.2 Factors combination . 66 5.2.3 Relationship with the reconstruction methods . 67 5.3 Baseline performance testing . 67 5.3.1 Performance hypothesis . 68 5.3.2 Applicability to the studied objets. 68 5.4 Performance Acceptance criteria . 69 5.5 Test planning . 70 5.5.1 Key scenario . 70 5.5.2 Modeling data and user variability . 70 5.5.3 Collected metrics . 71 6 Performance Testing Implementation 73 6.1 Testing environment . 73 6.2 Test implementation . 76 6.3 Test execution . 76 6.4 Test results . 79 6.4.1 Responsiveness (FPS) . 79 6.4.2 Triangle throughput (TPS) . 80 6.4.3 Batch throughput (BPS) . 80 6.5 Verification . 88 6.6 Baseline conclusions . 92 6.7 Performance-testing conclusions . 93 6.8 Real data performance . 94 7 Conclusions, Recommendations and Future Work 97 7.1 Conclusions . 97 7.2 Main contributions . 98 7.3 Recommendations and future work . 99 1 INTRODUCTION The Port of Rotterdam, as one of the largest in the world, executes multiple processes important for its daily operations using a a substantial amount of information mostly expressed as 2D line drawings. How- ever, many tasks related to underground utilities require the use of 3D information to extract their depth, compute the available space to lay down new pipes and cables, perform checks for data overlaps on both crossing and straight segments, plan maintenance procedures based on the actual three-dimensional dis- position of the assets, deduce relationships between underground utilities and assets above the ground, among many other tasks. The availability of 3D data is a requisite to perform this tasks, but is not a sufficient condition to com- plete them, requiring additional analytical and visualization tools. In particular, the visualization of pipes and cables is required to comprehend the situation on three dimensions not only for planning and main- tenance purposes, but for also for communication and validation of analyses and results. However, the visualization of 3D lines on the screen introduces a problem to the user as they lack of volumetric appear- ance, required to produce depth perception and key to understand the disposition and relationship of the objects on the screen. To solve this problem, volume should be added to non volumetric 3D lines in a process referred during this research as reconstruction, creating the outer shell of the desired object using only triangles and making them suitable to realtime rendering using computers equipped with Graphics Processing Units (GPUs). With the recent creation of WebGL, a technology enabling 3D content embedded on the web browser, and the interest in building 3D applications on the web displaying pipes and.
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