臺灣博碩士論文加值系統

這篇論文以物理上的力學系統為架構，探討船在虛擬實境(virtual reality)上的建模以及運動的模擬。我們使用搭載NVIDIA GeForce Go 7400顯示卡的電腦（CPU @2.00GHz）即時的建構一個海洋表面來當做我們的虛擬場景，海浪的大小是根據地心引力及風的方向與強度來產生，在此我們引入海洋學上的波譜理論。另外，為了達到真實與即時的場景繪製，採用圖形處理單元(GPU)來協助並完成著色，同時動態海面上的反射現象與菲涅耳(Fresnel)效應也被我們所考慮。在建構船舶模型上，所受的力與力矩是根據動態海浪的流體力學理論來施予。我們提出一個新的演算法對我們的船身格化成為點，並且依據3D中的數學理論將每個點在世界座摽中定位，並根據浮力去計算船舶在海面下的體積，以及其他流體力學的受力狀況，來模擬船的運動狀態，此外這個場景也可以被我們整合在六自由度的平台上去感知真實的運動情況。

This thesis is focused on the construction of physical dynamic system about the ship modeling and motion simulation on virtual reality. We introduce the deep ocean surface constructed as our virtual environment in real-time by personal computer which is mounted NVIDIA GeForce Go 7400 graphics card and 2.00GHz CPU. We introduce an ocean spectrum theorem, so the ocean wave is created by defining the gravity and the wind. Further more, in order to obtain the real-time and realistic rendering ocean scenery, we adopt Graphics Processor Unit (GPU) hardware on shading color. The reflection phenomenon and Fresnel effect are concerned on our dynamic ocean. On ship modeling, the forces and torques are calculated from the generated dynamic waves, which are based on the hydrodynamics and transferred to our ship model. We present a new algorithm to assign points on ship hull, and apply the 3D mathematics theorem to locate each point. According to the calculation of the volume of ship below the ocean surface, we can approach the dynamics of the ship. This simulation can also be integrated with the 6 degree-of-freedom motion platform to generate realistic motion sensation.

誌謝 II
摘要 III
Abstract IV
Table of Contents V
List of Figures VII
Chapter 1 Introduction 1
1.1 Background and Motivation 1
1.2 Related Works on Ship and Ocean wave modeling 3
1.3 Thesis Organization 7
Chapter 2 Ocean Dynamics and Rendering 8
2.1 Ocean Waves Modeling 8
2.2 Ocean Wave Parameters 11
2.2.1 Amplitude 11
2.2.2 Wavelength and Pulsation 16
2.2.3 Wave Direction 18
2.3 Ocean Rendering 19
2.3.1 Reflection and Refraction 20
2.3.2 The Fresnel Effect 23
2.3.3 Shading for The Ocean 26
Chapter 3 Ship Modeling and Dynamics 29
3.1 Preliminary Rigid Body Dynamics 29
3.1.1 Position and Orientation 29
3.1.2 The Velocity of a Rigid Body 32
3.1.3 Equations of Motion 33
3.1.4 Forward Euler Integration 35
3.2 The Ship Modeling 36
3.3 Ship Forces and Torques 39
3.3.1 Forces and Torques of Gravity and Sea Wave 41
3.3.2 The Wind Force 48
3.3.3 The Rudder and Propeller Force and Torque 50
Chapter 4 Implementation 52
4.1 Ocean Wave Modeling 52
4.1.1 Wave Modeling 52
4.1.2 Ocean Modeling 56
4.2 GPU Shading 61
4.3 Ship Modeling and Dynamics 64
4.3.1 Ship Modeling 64
4.3.2 Ship Dynamics 69
4.4 Integrated Simulation Loop 73
Chapter 5 Experimental Results 75
5.1 Ocean 75
5.2 Ship 79
5.3 System Integration with 6-dof Motion Platform 81
Chapter 6 Conclusions 84
References 86
Appendix 90

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