臺灣博碩士論文加值系統

影像的紋理(texture)在影像處理和電腦繪圖中扮演著相當重要的角色，在視覺效果上則有著畫龍點睛之效。近年來，紋理合成(texture synthesis)廣泛的應用在許多領域中以呈現視覺藝術的觀感，因此成為新穎且令人注目的研究方向。
本文將探討紋理合成在影像處理和電腦繪圖的研究領域，提出在影像處理上的改良方法，進而延伸出應用於電腦繪圖中紋理貼圖的方法。主要的想法是將一張紋理影像逐漸的貼在模型表面上，過程中會選擇出合適的表面區塊，直到將模型的整個表面都處理完畢來達到無接縫貼圖(seamless texture mapping)的目的。
在程序上先對三維模型表面進行分群處理，並逐次分層取得合適的三角面群(surface-cluster)以進行貼圖。貼圖的步驟首是把取得的三角面群轉換到二維的紋理座標空間，接著把紋理影像重新切割取樣來著繪在想要的表面上。經由不斷的選擇合適表面、空間轉換、取樣、著色在模型的眾多三角面群上，直到將紋理著繪到模型的全部表面上，而紋理的接縫處能有平滑的連續效果。
在上述的過程中，以有限的固定紋理樣本為取樣來源，所以只佔據少量的記憶體空間；保留原有的模型資料，也避免運算時間的增加以提高效率。最後對模型表面每一點產生對映的紋理座標，適用於標準的貼圖運算環境，提高在應用上的彈性。

In the last few years, texture synthesis techniques have been widely developed to improve visual effects in computer graphics related area. In this thesis we have designed and implemented two of these techniques. One is an improved texture synthesis technique in image processing, and the other is continual texture mapping applied to object surfaces.
Our image texture synthesis method is based on structural model and efficiently provides the generated texture with a natural static composition. Further, the new method also provides the application of texture transfer process. The continual texture mapping is to paste a texture onto an object surface repeatedly. During the processing, we find a suitable mesh patch continually and parameterize these mesh patch until all meshes of object surfaces are done.
Both our methods use only a source texture for sampling and synthesizing, and therefore just a little memory will be occupied for storing texture. After continual mapping process, we can get a set of texture coordinates corresponding to object surface and append the set of texture coordinates to the original object file. The original data of object surface are preserved to increase efficiency and flexibility on other applications. Through the association of geometric and texture coordinates, the rendering process has real-time performance.

CONTENTS
ABSTRACT i
ACKNOWLEDGEMENTS ii
CONTENTS iii
LIST OF FIGURES V
CHAPTER 1 INTRODUCTION 1
1.1 IMAGE TEXTURE SYNTHESIS 1
1.2 TEXTURE MAPPING 2
1.2.1 Shading Pipeline 3
1.2.2 Coordinate Systems 4
CHAPTER 2 RELATED RESEARCH 6
2.1 IMAGE TEXTURE SYNTHESIS 6
2.2 SURFACE TEXTURE SYNTHESIS 7
2.3 PATTERN MAPPING METHOD 7
CHAPTER 3 IMAGE TEXTURE SYNTHESIS 9
3.1 PATCH ARRANGEMENT 9
3.2 IMPROVED APPROACH 10
3.2.1 Improved Algorithm 11
3.2.2 Texture Transfer 14
CHAPTER 4 CONTINUAL TEXTURE MAPPING 17
4.1 CONTINUAL MAPPING PROCESS 17
4.2 DATA STRUCTURE OF SURFACES 20
4.2.1 Triangular Mesh 20
4.2.2 Corner Table 21
4.3 FACE CLUSTERING 22
4.3.1 Polygon Similarity 22
4.3.2 Clustering 24
4.4 LOCAL PATCH GROWING 25
4.4.1 Mesh parameterization 26
4.4.2 Greedy Method 29
4.4.3 Reversed Mesh Unfolding 32
4.5 QUANTITATIVE ANALYSIS 34
4.5.1 Distortion Measure 34
4.5.2 Continuity Measure 34
CHAPTER 5 RESULT 37
5.1 IMAGE TEXTURE SYNTHESIS 37
5.2 CONTINUAL TEXTURE MAPPING 44
CHAPTER 6 CONCLUSION AND DISCUSSION 49
REFERENCE 51

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