相同拓樸之多邊形網格物體的網格形變

Abstract

在三維空間中，一個任意形狀的物體漸漸轉變成另一個不同形狀物體的過程，我們稱之為三維物體形變（3D metamorphosis or 3D morphing）。 在目前的研究中，都必須將物體切割成多個對應區塊，並在各對應區塊內部產生物體的對應關係。如此使用者必須花相當多的時間和精神在 區塊的建立和特徵點的指定上。 本論文的主要目的是讓使用者只需給定兩物體上的特徵對應點，系統將自動產生具相同網格拓樸的新物體網格，進而完成網格形變的過程。 本論文結合Geometry Images[2002]和Interactive Geometry Remeshing[2002]的方式建立物體網格的切割和物體拓樸網格的重建。 尋找合適的切割路徑使網格能順利的映射到一個二維的平面上，在平面上建立物體的對應關係，再根據各物體的幾何資訊和 物體映射過程中的失真度求得新共同網格點的取樣。將分佈在二維平面上的取樣點經由受限制的狄勞尼三角化（constrained Delaunay triangulation）建立共同的拓樸網格， 並根據相同的拓樸網格重建各物體的幾何資訊。此由共同拓樸網格所重建的物體網格具有點的對應關係。 在形變過程中，根據時間變化利用線性內差的方式計算形變中的中間物體，完成物體的形變過程。

The metamorphosis or the 3D morphing is the process of continuously transforming one object into another. Most previous proposed techniques partition a given mesh into several patches. User often suffers from assigning partition paths and patch correspondence between objects. In this thesis, we aim to alleviate such user intervention. In the proposed morphing scheme, the user is required to specify only correspondence of feature vertices on objects. According to topological and geometric information, we find a suitable cutting path that cuts the given mesh into a single patch. We apply mesh parameterization to assign a 2D parametric value to each vertex on the patch, then adjust 2D parametric value for each feature vertex, and construct vertex correspondence on parametric domain. Using image processing technique and constrained Delaunay triangulation decides the point distribution and the topology of the new common mesh. Based on the common mesh and the original mesh geometry, we construct 3D meshes. In morphing stage,the interpolated mesh is constructed by a traditional linear interpolation between corresponding vertices.