삼차원 쉐이딩을 위한 스케치 기반 상호작용 시스템
Interactive Sketch-based System for 3D-look Shading
- 주제(키워드) Non-photorealistic rendering , 3D-look shading , 3D normal estimation , 2D sketches
- 발행기관 아주대학교
- 지도교수 이윤진
- 발행년도 2016
- 학위수여년월 2016. 2
- 학위명 박사
- 학과 및 전공 일반대학원 라이프미디어협동과정
- 실제URI http://www.dcollection.net/handler/ajou/000000021444
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
In this study, I propose a novel and efficient method to generate 3D-look shade illustrations from simple sketches having outlines and hatching strokes. The basic idea is to use the contours and hatching strokes specified by a designer as a metaphor for constructing a normal field for 3D-look shading effects. The overall shape of a 3D object is depicted with contours, such as silhouette contours and feature contours related to geometric ridges and valleys. The shading effects are achieved by means of hatching strokes, which are usually along the principal directions of the object’s local geometry. In my system, users first sketch an object’s outline and can draw a set of hatching strokes over its interior regions. Next, the system estimates the 3D normals of the points on the contours and hatching strokes. A smooth normal field is then generated by interpolating the estimated normals with the diffusion processes or multigrid-based linear system solvers. In addition, my system provides an intuitive method for adjusting normal transitions from edited to untouched regions using an alpha map. Finally, the texture coordinates of each pixel belonging to the drawn objects are computed based on the normal vector field so that the objects can be rendered in various 3D-look shadings, with changes for different materials and lighting. In the case global illumination effects are in demand, my system can construct a bas-relief model from the generated normal field to which advanced shading techniques like ray tracing or radiosity can be applied. Experimental results show that my system can easily and effectively generate illustrations having 3D-look shading effects from various 2D sketches drawn by users.
more목차
I. Introduction 1
II. Related work 6
1. Image-based approach 6
2. Sketch-based approach 7
III. Workflow Overview 12
IV. Contour drawing 15
V. Region segmentation and occluded regions recovery 17
VI. Control interior region normal vectors with hatching strokes 21
1. Estimation of normal vectors along parabola-like hatching strokes 22
2. Estimation of normal vectors along complicated hatching strokes 24
VII. Resolving convex-concave ambiguities of hatching strokes 28
VIII. Normal vector interpolation 30
1. Solving energy function for the interpolation 30
2. Multigrid equation solver for realtime responses 32
IX. Self-Occlusion Handling 39
X. Normal field editing 41
XI. Texture coordinates computation and rendering 44
XII. Normal field based construction of bas-relief meshes for global illumination 46
1. Height field construction by solving a linear least square system 47
2. Height field construction based on relative height 51
3. Triangular mesh construction from height field 55
XIII. Results 58
XIV. Discussion and Future Work 68
