- 學位論文
有關在NPR 3D動畫系統中模擬油畫之研究
Simulating the Oil Painting in an NPR 3D Animation System
摘要
Non-Photorealistic Rendering(NPR) 在圖學的領域中由來已久，此一特殊的成像方式不以物品的擬真度為優先考量，而是著重於筆觸(stroke)、繪畫風格(paint style)等的呈現。由於其成像多以誇張的手法呈現欲突顯的部分，而不注重其呈現出的正確精確性，因此適合用來模擬畫家的繪畫手法。 在本篇研究中我們藉由3D-model 與場景的原始資訊，來呈現出NPR 的連續且正確的筆觸生成影像，並且嘗試將研究成果套用並模擬出近似油畫風格的繪畫。我們從各種相關文獻與畫作中，歸納出油畫的風格特點在於顏料的堆積，以及單一筆劃中，多筆觸的疊合。以以往的研究為基礎，我們根據筆觸在物件上與物件邊緣的相對位置建立物件上全部筆觸的權重順序。並且，以此順序為基準，透過對畫布平面的動態分割，做出同一物件內筆觸區域性的分組，各組再以演算法做出筆觸的疊合。並記錄筆觸中顏料堆積厚度的資訊，實作出一對照此資訊，平面上有凹凸起伏的3D畫布。 本研究的主要貢獻，在於產生油畫特有的具有體積的筆觸，正確模擬油畫顏料在畫布上所應呈現的視覺效果：包括顏料的重疊堆積、顏色的疊加等等。
並列摘要
Non-Photorealistic Rendering (NPR) has been an important issue in the field of Computer Graphics. Instead of highlighting the realism of CG synthesized images, NPR focus on the representation of the stroke and paint style. One of the most important features of Non-Photorealistic Rendering is the exaggeration expression over the subjects of image. Therefore, NPR is suitable to synthesize images that simulate the paint style with the visual effect of strokes. The research issues of NPR can be roughly divided into two types, 2D image-based method and 3D model-based method. In this paper, we synthesize 3D model-based NPR images and animation with continuous volumetric strokes to simulate the visual effects of oil painting. According to our survey on oil paintings, we conclude that the heap of pigment and the volumetric property of each single stroke are two of the most important factors in the works of oil painting. According to the distance from the strokes to the edge of the object, we set up the priority of all strokes. Based on the order, through dynamically segmenting the canvas apart, we make the grouping with regional stroke in the object. And then pile strokes in the same group. The information of the thickness of strokes is stored in a Z-buffer-like data structure. The 3D canvas is then rendered based on this information. Main contribution of this research includes producing the volumetric strokes, and simulating the oil color correctly on the canvas. These goals are achieved by piling up the strokes on the same pixel, and superposing the pigments to simulate the final resulted color on the canvas.