光線追蹤與光柵化繪製下光影與位移表面效果差異之探討

Quality Comparison of Lighting and Displaced Surfaces Between Real Time Ray Tracing and Rasterization

王正皓(Wang Cheng-Hao)

指導教授 ： 張鈞法

國立臺灣師範大學/理學院/資訊工程學系/碩士(2019年)

https://doi.org/10.6345/NTNU201900588

摘要

在電腦圖學領域中，主要可分為兩種繪圖方法，一種是以省略複雜計算以換取高互動性的光柵化，以及以大量計算模擬光線行進方式取得精確結果的光線追蹤。光柵化以具備高互動性的畫面更新率著稱，然而隨著近年圖形顯示卡的計算能力大幅增長，使用光線追蹤來繪製結果的畫面更新率也有了大幅的成長，光線追蹤開始具備能配合人類反應速度的畫面更新率。而在這樣的狀況下光線追蹤該如何加入不同的材質與精確的光影效果來為畫面內容增添真實感，並利用光線追蹤的特性解決光柵化所會產生的畫面破綻就變得相當重要。

本論文透過使用Nvidia OptiX即時光線追蹤引擎，將模型表面做位移變形後進行光線追蹤繪製並維持良好的互動性，並與光柵化繪製的凹凸表面結果相比較。此外也比較光線追蹤與光柵化在光影繪製結果上的不同與破綻之處，讓將來使用光線追蹤繪製高互動性內容時能有充足的參考資訊。

關鍵字

光線追蹤 ； 光柵化繪圖 ； 位移映射 ； 陰影映射

並列摘要

How to render the lighting effects and displaced surfaces accurately in ray tracing is very important. This paper provides an implementation of displaced surfaces by using Nvidia OptiX 5.1 and OpenGL as graphical library, and presents the results of OptiX ray tracing and OpenGL rasterization. In addition, this paper also presents the results of comparison of shadow and reflection between ray tracing and rasterization.

This paper also provides the developers a report about the difference between GPU ray tracing and rasterization, and the possibility of using ray tracing to render interactive contents.

並列關鍵字

Ray Tracing ； Rasterization ； Displacement Mapping ； Shadow Mapping

參考文獻

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[2] Philipp S. Gerasimov. (2007). “Chapter 12. Omnidirectional Shadow Mapping, ” in GPU Gems. [Online]. Available : https://developer.nvidia.com/gpugems/GPUGems/gpugems_ch12.html

[3] Jerome Guinot. (2006). Vertex Displacement Mapping using GLSL. [Online]. Available : http://www.ozone3d.net/tutorials/vertex_displacement_mapping.php

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