在本論文的研究中，我們提出混合式液體表現模塑 (hybrid liquid representation modeling) 的技術應用於腹腔鏡手術模擬系統中。我們過去所提出的腹腔鏡手術模擬系統包括下列五個部分：即時的物理變形模塑、流血模擬、力回饋展現、快速的碰撞偵測、及手術動作。其中流血模擬系統結合了質點系統 (particle system) 和以方塊切割演算法(marching cubes algorithm)做的液體表面重建 (surface reconstruction)。為了改善液面重建的速度和增進視覺的效果，混合式液體表現模塑包含了三個部分：(i) 表面追蹤法 (surface tracking method)， (ii) 快速傅立葉轉換 (fast Fourier transform)，和 (iii) 動態質點表現法 (dynamic particle representation)。表面追蹤法和快速傅立葉轉換都是用來分類出在液面上的質點；但兩者結合在一起，可以獲得更好的效果。動態質點表現法是用來減少表面重建所需要的質點數目和時間。手術模擬所需要的平滑的血液表面與噴灑出的血珠，必須即時的展現。混合式液體表面模塑技術可以即時提供液面與獨立質點的表現，因此適用於手術模擬中的流血特效。 The laparoscopic surgical simulation has been a state-of-art topic in these years. One of the most challenging problems in the surgical simulation is the high fidelity of visual effects. In this paper, a computer graphics approach for simulating bleeding effects is proposed. The proposed hybrid liquid representation modeling (HLRM) approach combines traditional particle system with the isosurface representation using the marching cubes algorithm. For improving the performance and visual effects, the HLRM consists of three components: (i) surface tracking method, (ii) fast Fourier transform, and (iii) dynamic particle representation. The surface tracking method is used to classify particles near the liquid surface. Combining with the surface tracking method, the fast Fourier transform algorithm can be used to find the isolated particles. Finally a dynamic particle representation is proposed for saving the computation time of the marching cubes algorithm. It is essential to render the fair blood surface and sprayed blood needed in surgery simulation. HLRM is able to render the liquid surface and isolated particles in real time. Therefore our approach is suitable for bleeding effects in laparoscopic surgery simulation.
