近年來三維影像的應用非常快速的成長，並且也廣泛的應用到了電腦輔助設計、電腦圖型、動畫還有醫學...等等領域中使用。但隨著網際網路的快速發展，大量的數位資訊散佈在網路上，任何人都可以不經由原創者的授權，就輕易的取得所需的資訊，這種情形嚴重的侵犯到原創者的智慧財產權，所以對於數位智產保護措施也日趨重要。由於數位浮水印的技術可以用在相當廣泛的地方，不論是傳統的平面數位影像或者是最近的三維網目模型，都具有高度的可靠性，因此，吸引了越來越多的專家學者的注意與研究。
在本論文中，提出了兩種基於空間域中強健型浮水印的技術以及一種易碎型浮水印的技術。在強健型浮水印技術中我們發展出分別將不同的大小的浮水印資料量或者是不同強度的浮水印資料嵌入到不同結構的三維網目區域中的演算法；而對於易碎型，我們也改良的傳統的嵌入資料散佈的方式，並且結合查表的方式(Look Up Table)在嵌入資訊後不會對原始三維網目模型造成任何改變。
在大部分對於三維模型於空間域中的浮水印嵌入技術都是將浮水印資料以隨機抽取的方式加以嵌入到三維網目中，但是在基於這樣的遷入方法下，很有可能會造成嵌入的浮水印資料在三維模型中分布不均勻的狀況發生。不同於以往的技術，我們發展出了一種可以保證能夠均勻地分佈嵌入浮水印資料區域的方法。我們針對原始三維模型做分割的動作，並設定一門檻值(threshold value)來對各區塊的密度比較作為是否繼續分割的判斷，而每一次的分割可將該區塊劃分為八個大小相同的子區塊(sub-block)，並且再各區塊中所包含的都是一部分的網目資料，之後我們在嵌入浮水印資料到各目標區塊的網目資料中。
經過實驗的結果證明，所提出的浮水印演算法能夠有效的在經過攻擊後，包括隨機雜訊攻擊、網目簡化(mesh simplification)、切割攻擊後，仍然能有效的還原與驗證，達到保護影像智慧財產權之效果。

In the last years the applications using and managing 3D data are quickly increasing, the 3D geometric models have been widely used in areas such as CAD/CAM, Computer Graphics, animation, and medical applications. But nowadays are more and more people access digital 2D images or 3D models from Internet without licensing. Among all the research approaches that try to resolve this problem, digital watermarking is no doubt the most attractive one.
In this thesis, we proposed a two new spatial domain robust watermarking schemes for the triangular mesh model of three-dimensional object, first one we embedded the different amounts of watermark data into different 3D mesh structure area, and the other one we embedded the watermark data with different robustness into different 3D mesh structure area; and one fragile watermark to protect the multiple watermarks embedding attack.
Most of the previous spatial domain schemes embed watermark data with a random insertion strategy, the distribution of embedded data may be uneven. Unlike these methods, we develop a strategy to guarantee the even distribution of watermark data. We first calculate the smallest cubic sub-block of various sizes. Whenever the total density in a block exceeds a threshold value, the block is divided into 8 equal size cubic sub-blocks. Each block may contain a piece of triangular mesh, in which a fixed amount of watermark signal is embedded. The experimental results shows that the proposed watermarking scheme could survived the additive random noise, and mesh simplification, cropping and multiple watermark embedding attack, and provide well authentication to prove the copyright of rightful owner.

Abstract i
Contents iii
List of Table v
List of Figures vi
Chapter 1 INTRODUCTION 1
1.1 Motivation 1
1.2 Digital Watermarking Technique 2
1.3 The Classifications of Digital Watermarking Technique 4
1.3 .1 Visible and Invisible Watermarking Technique 4
1.3 .2 Robust and Fragile Watermarking Technique 4
1.3 .3 Spatial and Frequency Watermarking Technique 5
1.4 Structure of Thesis 6
Chapter 2 Related Research 7
2.1 Digital Watermarking for 3D Models 7
2.1.1 The Embedding Requirements of 3D Watermarking Technique 8
2.2 Embedding Targets 10
2.3 Previous 3D Watermarking Techniques 11
2.3.1 Robust 3D Watermarking Techniques 11
2.3.2 Fragile 3D Watermarking Techniques 14
2.4 Watermark Binding Scheme 15
Chapter 3 A Watermarking Algorithm for Image Copyright Protection 16
3.1 Introduction 16
3.2 Three-Dimensional Mesh Simplification 16
3.3 Human Visual System 18
3.3.1 Space Masking Effect 19
3.4 The Watermark Strategy 20
3.4.1 Embed with Different Amount of Watermark Data 22
3.4.1.1 Computing Block Division 22
3.4.1.2 Branch Sub-block Analysis 23
3.4.1.3 Watermark Embedding Process 24
3.4.1.4 Watermark Extraction Process 26
3.4.1.5 Discussions 27
3.4.2 Embed with Different Strength of Watermark Data 32
3.4.2.1 Computing Block Division 32
3.4.2.2 Branch Sub-block Analysis 33
3.4.2.3 Watermark Embedding Process 34
3.4.2.4 Watermark Extraction Process 36
3.4.2.5 Discussions 37
Chapter 4 A Watermarking Algorithm for Image Authentication 42
4.1 Introduction 42
4.2 The Yeung’s Fragile Watermarking Algorithm 43
4.3 The Watermark Strategy 44
4.3.1 Block Division 45
4.2.2 Watermark Embedding Process 47
4.2.3 Watermark Verification Process 48
4.3 Discussion 49
Chapter 5 Conclusion 52

REFERENCES 54

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