在網線光譜基底上計算熱輻射並利用硬體加速的全域照明

Global Illumination by Radiosity on Mesh Spectral Basis with Hardware Acceleration

林奕瑱(Yi-Chen Lin)

指導教授 ： 王俊堯 ； 張鈞法

國立清華大學/電機資訊學院/資訊工程學系/碩士(2009年)

摘要

在圖學領域中，全域照射至今一直是個許多值得研究的課題。如何快速並精確地繪製出全域照射的影像一直是3D圖學中的最終目標。在此篇論文中，我們結合了熱輻射照射和預先計算輻射轉換法的概念。熱輻射演算法原本即是計算低頻的間接照射。之後，我們先進行預先計算，得到網線光譜基底與輻射轉換函數，再將熱輻射的計算域轉換至網線光譜基底，便可在繪圖時快速地處理低頻的間接照射。由於所有的預先計算皆是與視角及光源獨立，故在繪製時，我們能達成即時視角轉換和互動的重新打光。而在預先計算中，引入現今的繪圖硬體的加速以及實作一個階層式資料結構，便可大量地減少預先計算的時間。同時配合使用者可選擇的品質選擇，可控制我們在即時熱輻射中的虛擬點光源取樣數，而使得此篇論文同時能繪製出較精細的3D場景，或是達成一個快速繪製的全域照射預覽效果。

關鍵字

網線光譜基底 ； 熱輻射 ； 全域照明 ； 電腦圖學 ； 預先計算

並列摘要

Global illumination now is still a good research issue in 3D graphics. How to render a photorealistic image fast remains to be a destination. In this thesis, we combine the Radiosity and the Pre-computed Radiance Transfer (PRT) to render our final image. Instead of computing the Radiosity directly on patches, we pre-compute a set of mesh spectral basis and project the computing domain onto this basis, which can calculate the low-frequency indirect lighting faster. This thesis achieves a real-time view-changing and an interactive-time relighting since all pre-computations are view-independent and light-independent. With the acceleration of graphics hardware, we apply the Bounding Volume Hierarchies (BVH) on GPU, and thus reduce the pre-computation time hugely. Finally, we make this application’s rendering quality as user-controllable for users to choose the number of virtual point light source (VPL). By this, our thesis can render the 3D scene with more accuracy, or alternatively, it can be a fast preview system for global illumination.

並列關鍵字

Mesh Spectral Basis ； Radiosity ； Global Illumination ； Computer Graphics ； Bounding Volume Hierarchy ； BVH ； PRT

參考文獻

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