使用個別像素位移的方法對表面細部效果的即時呈像

Interactive Rendering of Surface Details using Per-pixel Displacement

沈宗男(Zong-Nan Shen)

指導教授 ： 張鈞法

國立清華大學/電機資訊學院/資訊工程學系/碩士(2007年)

摘要

三維模型的複雜度對產生的影像的品質有很大的影響。愈複雜的三維模型具有較好的影像品質。然而，一個三維場景中包含許多三維模型，如果每一個模型都使用大量的三角片，那麼即使是最新、最快的圖形處理器也無法維持一定的顯像速度。在電腦圖學中，通常使用存有高度場表面的深度資訊的貼圖，對幾何模型上的每一點做位置上的改變。目的是使簡單的模型也能呈現出複雜模型的效果同時具有快速的顯像速率。產生的視覺效果中，因為模型表面的曲度造成的輪廓效果通常被忽略。在論文中，我提出一個以基於影像的方法，能即時呈現出視差、遮蔽、陰影、以及輪廓的效果。同時，我也對之前相關的方法做一個深入的探討與比較。

關鍵字

藉由影像繪圖 ； 位移貼圖 ； 即時繪圖系統

並列摘要

The complexity of model influences the quality of rendering. However, even the latest powerful graphics hardware can not afford too many models with high polygon count in the scene. In computer graphics, a depth map which encodes the information of height field surface may be used to displace original geometry surface. Therefore, the rendering of low polygonal surface can reach the same quality as a more complex model of much higher polygon count. There are several effects caused by height field surfaces. Among these effects, the silhouette is an important feature but is often neglected in the rendering. In this thesis, I proposed an image based technique which uses geometry normal and tangent maps to render surface details such as motion parallax, self-shadow and silhouette at interactive rates. I also provide in-depth survey of related methods and summarize their respective capabilities and drawbacks for comparison.

並列關鍵字

image based rendering ； displacement mapping ； interactive rendering

參考文獻

[1] J. F. Blinn, Simulation of wrinkled surfaces, SIGGRAPH, 1978.

[3] R. L. Cook, Shade trees, SIGGRAPH, 1984.

[4] W. Donnelly, Per-Pixel Displacement Mapping with Distance Functions, GPU Gems II, 2005.

[9] N. L. Max, Horizon Mapping: shadows for bump-mapped surface, The Visual Computer, 1988.

[10] M. McGuire and M. McGuire, Steep Parallax Mapping, I3D Poster, 2005.