第四章 實驗結果與討論
4.5 限制
國
立 政 治 大 學
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Na tiona
l Ch engchi University
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4.5 限制
我們以 image space 的方式實作了多層的折射，雖然效能上優於光線追蹤法，
然而當折射的層數提升，因為資料是以貼圖的方式傳遞，而受限於貼圖的解析度，
我們方法的解析度也因而下降，也容易在斷層與全反射處產生錯誤的結果，如圖 4.22。
雖然一個場景中並不會有太多的折射模型，但隨著越多折射模型的或者太過複雜 的模型加入都會造成效率的降低，此外，我們目前因效能的考慮而對每一個模型 都只做四層的折射，因此會有無法正確顯示的部分。
圖 4.22: (a) 場景設計 (b) blender render (c) 我們的方法
為了提升解析度的問題，我們以 Procedural texture 的技術繪製環境貼圖，我 們發現隨著環境貼圖的解析度提升，其結果中許多的雜訊會消失，換言之越接近 Procedural texture 的結果，如圖 4.23 中紅色圈起的部分。
‧ 國
立 政 治 大 學
‧
Na tiona
l Ch engchi University
54 (a)
(a) (b)
(c) (d)
圖 4.23: (a) 環境貼圖解析度 256*256 (b) 環境貼圖解析度 512*512 (c) 環境 貼圖解析度 1024*1024 (d) 環境貼圖以 Procedural texture 繪製
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數可以運用 depth peeling 分解的深度來運算，因此我們採用了 Depth peeling 的方 法將模型分成四層，使得有別於光線追蹤的方法，在計算折射模型時不需在光線‧
慮樣許多步驟一起執行，例如折射的計算有無可能與 depth peeling 同步處理，又 或者多個物體的計算，以多層的場景來處理。‧
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