臺灣博碩士論文加值系統

隨著電腦動畫、遊戲等相關創作越來越普遍的現況下，使用者往往對模型的要求越來越高，不但要求精美還要求順暢，而這些模型可能太過精細進而導致讀取緩慢、運算需求過多、偵數(frame rate)過低等等的問題。為了因應模型要求精緻並且執行順暢的目的，目前有許多以利用視覺上還原模型細節的方式，將模型簡化並在視覺上營造出保留模型細節的效果，並能在各應用時執行順暢的目的。
本研究使用Bump mapping為研究基礎，尋找一個產生Height Map的方法，利用模型簡化前後頂點與表面的高度差製作對應的Height Map。在模型簡化後頂點可保留其二維材質座標的特性下，把簡化前之各頂點的材質座標，於簡化後各表面頂點的材質座標所形成的二維三角網格中做判斷，計算在三維空間中該點與該表面的距離作為高度資訊，利用這些所得的高度資訊製作Height map，再將此Height Map轉換為Normal map後，即可對簡化後的模型進行Bump mapping還原模型精細度。

We present an approach for producing the height map with model simplification based on bump mapping. We use the 2D graphics generated by model parameterization to determine the height distances of vertices and surfaces between model simplification. After that, we generate the height map according to their height distances and texture coordinate.
After generating the height map with the model simplification, we use the height map to do bump mapping on the simplified models. Finally, we achieve the goal of reduction the model’s realistic on simplified models.

謝誌 i
摘要 ii
ABSTRACT iii
目錄 iv
圖目錄 vii
表目錄 ix
第一章 簡介 1
1.1 研究背景 1
1.2 研究動機與目標 1
1.3 開發環境與硬體規格 3
1.4 研究架構 4
第二章 相關研究 5
2.1 模型簡化 5
2.2 Billboard clouds 6
2.3 Bump mapping 7
2.4 Bump mapping延伸技術 10
第三章系統架構 12
3.1 模型的參數化與簡化 12
3.1.1 模型的參數化 13
3.1.2 模型的簡化 17
3.2 Height Map運算與製作 19
3.2.1 高度值的運算 19
3.2.2 Height Map的製作 24
3.3 使用GLSL加速運算 25
3.4 Bump mapping的應用 28
3.4.1 將Height Map轉換為Normal map 28
第四章 結果與討論 30
4.1 研究結果與討論 30
4.2 高度值的正規化處理 31
4.3 Height Map 平滑化 34
4.4 將模型切割分別取得其高度值再縫合 36
4.5 各模型FPS提升結果 37
第五章 結論與未來方向 39
REFERENCES
附錄 43
壹、 Tangent space的運算 43
貳、 Gauss-Seidel演算法 45

[1] S. Kumar, D. Manocha, B. Garrett, M. Lin ”Hierarchical Back-Face Culling,” Eurographics 1996.
[2] W. J. Schroeder et al., “Decimation of triangle meshes,” Computer Graphics(SIGGRAPH ’92 Proc.), 26(2):65–70, July 1992.
[3] M. Soucy and D. Laurendeau. “Multiresolution surfacemodeling based on hierarchical triangulation,” Computer Vision and Image Understanding, 63(1):1–14, 1996.
[4] J. Rossignac and P. Borrel. “Multi-resolution 3D approximations for rendering complex scenes,” In B. Falcidieno and T. Kunii, editors, “Modeling in Computer Graphics: Methods and Applications,” pages 455–465, 1993.
[5] D. Luebke and C. Erikson.” View-dependent simplification of arbitrary polygonal environments,“ In SIGGRAPH 97 Proc, August 1997.
[6] H. Hoppe. “Progressive meshes,” In SIGGRAPH ’96 Proc., pages 99–108, Aug. 1996.
[7] H. Hoppe et al., ” Mesh optimization,“ In SIGGRAPH ’93 Proc., pages 19–26, Aug. 1993.
[8] R. Ronfard and J. Rossignac. “Full-range approximation of triangulated polyhedral,” Computer Graphics Forum, 15(3), Aug. 1996. Proc. Eurographics ’96.
[9] A. Gueziec. “Surface simplification with variable tolerance,” In Second Annual Intl. Symp. on Medical Robotics and Computer Assisted Surgery (MRCAS ’95), pages 132–139, November 1995.
[10] M. Garland and P. Heckbert, “Surface simplification using quadric error metrics,” ACM SIGGRAPH Computer Graphics, 1997, pages 209 – 216
[11] X. Decoret et al., “Billboard Clouds,” INRIA, June 2002
[12] J. F. Blinn, “Simulation of wrinkled surfaces,” SIGGRAPH Comput. Graph. 12,3(Aug.1978), 286-292
[13] M. Peercy et al.,“Efficient Bump Mapping Hardware,” Computer Graphics, 1997, Pages 303-306
[14] Y. Wang, et al. (2002). "Fast normal map generation for simplified meshes." J. Graph. Tools 7(4): 69-82.
[15] M. Tarini et al., “Real Time, Accurate, Multi-Featured Rendering of Bump Mapped Surfaces,” Computer Graphics Forum, Volume 19, Issue 3, pages 119–130, September 2000
[16] T. Kaneko et al., “Detailed Shape Representation with Parallax Mapping,” Int Conf Artif Real Telexistence, 2001, Pages 205-208
[17] F. Policarpo et al., “Real-Time Relief Mapping on Arbitrary Polygonal Surfaces,” Symposium on Interactive 3D Graphics, 2005, Pages 155-162
[18] L. Szirmay-Kalos, T. Umenhoffer,“Displacement Mapping on the GPU - State of the Art,” Computer Graphics, Forum, Volume 27, Issue 6, pages 1567–1592, September 2008
[19] W. Tutte. “Convex Representation of Graphs,” Proc. London Math. Soc. 10 (1960), 304-20.
[20] T. Needham. ”Visual Complex Analysis,” Oxford, UK: Oxford Press, 1994.
[21] W. Tutte.” How to draw a graph,” Proc. London Math. Soc, 1963 - Citeseer
[22] M. Eck et al., “Multiresolution Analysis of Arbitrary Meshes,” In Proc. of ACM SIGGRAPH, pp. 173-82. New York: ACM, 1995
[23] M. S. Floater. “Mean Value Coordinates,” Computer Aided Geo-metric Design 20:1 (2003), 19-27.