動態環境中有效的聚集化階層式熱輻射法之研究

Abstract

近年來，階層式熱輻射法在電腦圖學中已成為一個成熟的研究領域，然而 要把它應用在動態環境中，仍然有許多課題值得研究。在本論文中，我們 延伸階層式熱輻射法的作法將之應用在動態環境中。當物體在動態環境中 被改變位置，我們提出一個新的方法使得環境中受影響的能量連結（ energy links）能迅速並有效的確認出來，而這些連結的Form factors將 被重新計算，接著階層式熱輻射法將持續以漸近式的作法求得熱輻熱之解 。當環境中的熱輻射能降低時，我們提出所謂記錄連結（history links ）用來作mesh un-refinement，使得我們可以根據當時的熱輻射狀態，維 持一正確的切割層次（subdivision level）。此外，我們亦利用聚集化 法（clustering），在聚集與聚集之間建立聚集連結（cluster links） ，用來降低初始連結（initial links）所需的時間以及整體連結的數目 。最後，我們採取了一個改良的漸近式策略用避免不必要的連結之建立， 不但使得整體的熱輻射模擬過程具有更佳的互動效果，也使得在動態的處 理過程的效率因連結數目的減少而提高。由我們的實驗結果顯示，我們的 方法的確提供了一個簡單但有效的動態架構。 Recently, hierarchical radiosity became the fertile areas ofresearch. However, it opens new frontiers for exploration, while applying in dynamic environments.This thesis extends the basic ideas of hierarchical radiosity to dynamic environments. When the object is repositioned in the dynamic environments,the links which are occluded by both the object's original position, and new position, and the links emanating from the moving object to the environment areidentified rapidly by means of our proposed new strategy.Then the involved form factors are recomputed, and the solution cycles are resumed.As the total net energy of the environemnt is decreased,we exploit the so-called history links to un-refine the effected patches.Furthermore, to make the whole algorithm more efficient, we try to reduce the initial links by means of surface clusters or objects whichresult in cluster links in addition to the traditional energy links. Also an effective progressive refinement strategy is applied in ouralgorithm.This strategy provides the simulation with the improved refinement criteriafor avoiding the creation of unnecessary linkswhich makes more interactive progressive refinement possible.As the experimental results shown, our approaches exactly provide a simple but effective dynamic framework.