非等向性散射之光影模型及其即時顯像

Abstract

在互動式系統中，由於視角、光源、場景以及環境參數都需動態更改，所以光散射的繪圖效果通常難以呈現。近年來在某些假設與簡化之下，散射之光影模型技術已大幅提高顯像的效能。在本論文中，我們提出一個針對動態、準確以及單非等向性散射之光影模型。這樣的模型適用於霧、煙等場景。我們的模型針對均勻光散射介質中的點光源，以一個根據角度化公式表示散射積分。使用者可以根據一些簡單的參數例如密度或是正向散射性來創造一個動態的散射場景。我們利用我們的模型展示光源的光暈散射以及表面輻射的較果。這模型可以結合現有顯示卡達到即時的效果。

Rendering the effects of light scattering for interactive applications is often made difficult by the demands of dynamic viewing, lighting, scene geometry, and environment parameters. Recent advances in rendering of participating media using analytic techniques have enhanced performance significantly to meet this challenge, albeit under assumptions and simplifications made to scenes. In this thesis, we present an analytic lighting model for dynamic, accurate, and single anisotropic scattering that may be used for scenes such as fog, mist, or haze. Our model applies an explicit analytic integration to an angle-formulated single scattering integral for a point light source in a homogenous participating medium. Users may create a dynamic scattering environment, such that scattering conditions may be controlled using simple parameters for density and forward scattering level. Using this model, we demonstrate the effect of forward scattering on glows around light sources and surface radiance. The method can be implemented on programmable graphics hardware in real-time.