以路徑追蹤繪製可見光光譜的色散現象

Bidirectional Path Tracing for Dispersion of Visible Light

劉詠蓁(Liu Elvire)

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(2021年)

https://doi.org/10.6345/NTNU202100234

摘要

近年來，計算機圖學領域隨著 GPU效能的快速提升，光線追蹤自從多年前提出後快速進展成能夠實時呈現在大眾前的樣貌。我們將以CUDA 作為基礎，利用 GPU 的分散式運算引擎來更加高效率地解決光線追蹤這個較為複雜的計算。
光譜渲染器可以實現幾種在一般光線追蹤看不太到的特殊光學現象，例如散射和螢光。由於光譜渲染必須對光譜域進行採樣，由於採樣的成本高、計算量大，導致收斂速度非常差，在實際發射或反射光譜方面得到每增加採樣次數，計算量倍增的場景。我們提出針對材質改變採樣次數的非均勻採樣頻譜渲染：當光線打到折射材質時進行更多的射線採樣，這是一種簡單又有效果的方法。
我們建置了一組測試場景，由於我們的方法使用到非均勻光譜的處理，我們將所有場景位置形狀保持相同，對照組為均勻採樣，實驗組使用一組測量的非均勻的重要性採樣。
最後，我們對不同的頻譜採樣方式進行了比較，並發現我們的方法大大減少了均方誤差，在各種困難的情況下，只需很少的開銷就可以減少顏色噪音以及在原始經典的渲染器中的繪製。

關鍵字

路徑追蹤 ； 頻譜採樣

並列摘要

Spectral renderers are capable of reproducing several advanced phenomena of light, such as chromatic dispersion and fluorescence.
The following paper will discuss our spectral render algorithm in CUDA, which is based on faster GPU parallel processing system. We construct a set of test scenes, as our method works on nonuniform spectra sampling, we keep all scenes geometrically identical, but vary material using sets of measured nonuniform reflectance spectra with importance sampling.
At as spectral renderers must sample the spectral domain, they are typically a drag on sampling issues leading to notably poor convergence rates, which are reinforced when reflectional materials are involved in otherwise simple scenes.

並列關鍵字

Path Tracing ； Spectral Sampling

參考文獻

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