基於結構特性至物理性質之三維物件風格與重定位

Retargeting and Styling 3D Objects from Structure Preservation to Physical Fabrication

黃群凱(Chun-Kai Huang)

指導教授 ： 陳炳宇

國立臺灣大學/電機資訊學院/資訊工程學研究所/博士(2018年)

https://doi.org/10.6342/NTU201803534

摘要

三維模型廣泛的運用於現今的電腦圖學，不止運用在電影、動畫、遊戲等娛樂產業的人物設計，更用於加工製造業的成品設計，近些年隨著行動裝置與虛擬實境的普及，三維模型更用於建築設計和都市計畫的樣品與展示。然而要建購一個三維模型，不論是掃描真實物體或由人工設計生成，都需要花費相當多的時間與資源。 本篇論文重點在於提出三種模型重定位 (retargeting) 方法，本論文的重定位方法以結構保留為最大考量。重定位方法將對輸入的三維模型進行結構分析，並保留結構的前提下生成出不同格局的三維模型或轉換成不同風格的三維模型。首先，本論文提出一個基於骨骼形變模型的方法來將輸入的角色模型轉換成可愛版 (super-deform) 模型。接著，本論文提出另一個方法能夠考慮模型重覆性結構細節，該方法可將模型重定位成不同的格局與大小，生成的新格局模型與原先的模型有相同的重覆性結構細節。同時，本論文考慮到模型形變時的貼圖紋理 (texture) 將會改變的現象，進而提出一套可保留原本紋理的技術。最後，本論文提出一個考慮模型生成且能穩定站立的方法，該方法將輸入的模型轉換成樂高積木的組裝格局，同時計算積木的重量分佈。該方法所輸出的組裝格局將符合使用者輸入模型的形狀、顏色，並保證積木組裝組裝後能穩定站立而不崩垮。

關鍵字

三維計算機圖學 ； 三維模型形變 ； 樂高模型 ； 基於物理穩定設計 ； 三維模型生成 ； 逆程序化建模 ； 重複性結構 ； 貼圖材質 ； 單射轉換

並列摘要

The three-dimensional content creation is one of the critical challenges of modern computer graphics. Due to the real-world acquisition and handcrafted modeling consume a lot of time and resources. The goal of this dissertation is that proposes a series of the 3D object retargeting methods which can be used to synthesize new 3D contents and different representation of 3D objects.

In this dissertation, we first introduce a novel technique to create an SD style counterpart of a normal 3D character model. Our approach uses an optimization guided by a number of constraints that can capture the properties of the SD style. Then, we present an interactive method suitable for retargeting both 3D objects and scenes. Initially, the input object or scene is decomposed into a collection of constituent components enclosed by corresponding control bounding volumes which capture the intra-structures of the object or semantic grouping of objects in the 3D scene. The overall retargeting is accomplished through a constrained optimization by manipulating the control bounding volumes. Meanwhile, we propose an automatic UV map adjustment method which preserves the original texture appearance after deforming the 3D mesh. Lastly, we present a stability analysis and layout refinement algorithm that iteratively improves the structure around the LEGO bricks, allowing for automatic generation of a LEGO brick layout from a given 3D model, accounting for color information, required workload (in terms of the number of bricks) and physical stability.

並列關鍵字

three-dimensional computer graphics ； deformation ； LEGO ； stability-aware design ； fabrication ； inverse procedural modeling ； structure regularity ； texture ； injective mapping

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