程序性的輪廓線繪製方法

Procedural Silhouette Edge Drawing

在電腦圖學的發展過程中，非寫實性算圖的技術在近幾年受到相當程度的重視。相較於寫實性算圖以模擬真實的自然影像為目的，非寫實性算圖提供更為簡練、且更具人性化的圖像表達方式。而在非寫實性算圖的操作流程中，程序性的操作方式雖然提供了使用者較為簡便的操作流程。然而，由於程序性的演算流程中缺乏與使用者之間的互動，最終產生的影像仍不免會有過於制式且缺乏人性化等缺點。 由於輪廓線是描述物體形體的重要特徵線，因此本論文將以輪廓線為例，提出一套以線條拓樸為基礎的筆畫建構流程。透過使用者建立筆畫規則以組合基本筆畫單元，賦予輪廓線較具人性化的表現方式。本文首先簡述程序性非寫實性算圖架構，接著文獻探討部分將針對已發表之非寫實性算圖的基本演算原理以及非寫實性算圖中線條式樣逐一探討，然後詳述本論文所提出的程序性非寫實性算圖架構與其演算法，最後並以實做及相關成果佐證論文的研究。 In the development of computer graphics, non-photorealistic rendering (NPR) technology has been a focus of research in recent years. In comparison with photo-realistic rendering which simulates realistic natural images, NPR provides more concise and humanistic expressiveness in images. Among the many types of workflow in NPR technology, the procedural type provides the user an easier and simplified workflow. However, procedural NPR algorithms usually produce uniform and non-humanistic images due to a lack of interaction with the user. Since silhouettes are an important feature of edges for expressing the shape of an object, our work takes silhouettes as examples to propose a stroke construction workflow based on edge topology wherein users can combine pure stroke elements according to user-defined rules for their formation. Thus, more humanistic expressions can be added to the resulting silhouettes. First, the procedural NPR framework for stroke generation is outlined. Then, the mainstream NPR techniques and their respective theorems are discussed, followed by an introduction to the framework and algorithm of the proposed system and a discussion thereof. Finally, the feasibility of the proposed framework is illustrated by a sample algorithm, after which pertinent research results are presented.