整合體積型筆觸與Relief Mapping技術的NPR系統

Integrating Volumetric Strokes and Relief Mapping in a NPR System

林碩彥(Shuo-Yan Lin)

指導教授 ： 陳履恆

國立暨南國際大學/科技學院/資訊工程學系/碩士(2010年)

摘要

非擬真成像在計算機圖學中是一門很重要的議題，它可以呈現出有別於相片擬真的效果。為了在畫布上以NPR圖像的方式來呈現油畫、紙雕具有三維的特性，我們探討藝術在三維層面上不同的表現形式。在這篇研究中，我們提出了一個以三維模型作為基礎具有體積型筆觸效果的即時NPR系統。藉由整合筆觸模擬、筆觸合併和以素描為基礎的模型技術到NPR系統中，產生能呈現各種三維藝術風格的NPR圖像，例如淺浮雕、油畫等。

此外，我們採用Relief Mapping技術去對我們的圖像作即時繪圖。Relief Mapping是一種進階的紋理貼圖技術。它能夠根據不同的觀察角度去做像素位移，更真實的表現物體表面的細節。我們首先整理體積型筆觸的高度資訊，將之轉換成高度圖。然後根據這張高度圖，自動去計算相對應的法線圖資訊，最後，將上述資訊導入到我們的Relief Mapping程式中，去產生一個具有高度體積感視覺效果的NPR圖像。透過我們系統，使用者可以即時地藉由改變攝影機還有光源的角度與位置去觀察具有體積視覺效果的藝術作品相對應的變化。

關鍵字

非擬真成像 ； 計算機圖學 ； 素描建模 ； 筆觸 ； Relief Mapping ； 淺浮雕 ； 黏土浮雕 ； 油畫 ； 紙雕

並列摘要

NPR (Non Photo-Realistic Rendering) is an important issue in Computer Graphics. It can present a totally different style from realistic methods. To represent 3D characteristics on canvas of oil-painting and paper sculpture in NPR images, we survey different forms of art representation with 3D aspects. In this paper, we propose a 3D-model based real-time NPR system with volumetric stroke effects. By integrating stroke simulation, strokes merging, and sketch-based modeling techniques into a NPR system, we synthesize NPR images which represent different 3D art styles such as bas-relief sculpture, oil painting and so on.
In addition, we adopt a relief mapping technique to render our images in real time. Relief mapping is an advanced texture mapping technique. It is able to represent more realistic surfaces by displacing texel according to different viewpoint. The height information of volumetric strokes is first converted into a height map. Based on this height map, the corresponding normal map information is then calculated automatically. Finally, the above information is imported into relief mapping modular to generate a NPR image with height and volumetric visual effects. Through our system, user can observe the corresponding variation of art works with volumetric visual effects by changing the angle and position of camera and light source in real time.

並列關鍵字

Non-Photorealistic Rendering ； Computer Graphics ； Sketch-Based Modeling ； Stroke ； Relief Mapping ； Bas-relief Sculpture ； Clay Relief ； Oil Painting ； Paper Sculpture

參考文獻

[1] Alexander Belyaev, “Mesh Smoothing and Enhancing. Curvature Estimation”, 2006.

[2] Aaron Hertzmann, Ken Perlin , "Painterly Rendering for Video and Interaction", Proc. of Non-Photorealistic Animation and Rendering 2000, 2000.

[3] Chung-Yu Yang, “Model Simplification Using Relief Mapping”, National Tatung University, Master Thesis, 2008.

[4] Fábio Policarpo et al., “Real-Time Relief Mapping on Arbitrary Polygonal Surfaces,” Symposium on Interactive 3D Graphics, 2005, Pages 155-162.

[5] Hsiao-Yi Chang, “Using Texture Synthesis Technique on Relief Mapping”, National Tatung University, Master Thesis, 2009.