Structure grid for directional stippling

• Published in: Graphical models Vol. 73; no. 3; pp. 74 - 87
• Main Authors: Son, Minjung, Lee, Yunjin, Kang, Henry, Lee, Seungyong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.05.2011; Elsevier
• Subjects: Algorithms; Applied sciences; Artificial intelligence; Computer science; control theory; systems; Exact sciences and technology; Hatching; Hedcut illustration; Illustrations; Mathematical models; Orientation; Pattern recognition. Digital image processing. Computational geometry; Rendering; Stippling; Surface layer; Texture; Texture synthesis; Texture synthesis; Hedcut illustration; Stippling; Hatching; Cell structure; Alignment; Hatching(image); Spacing; Orientation; Texture
• ISSN: 1524-0703; 1524-0711
• DOI: 10.1016/j.gmod.2010.12.001

This paper presents a novel method to convert a photograph into a stipple illustration. Our method addresses directional stippling, where the collective flows of dots are directed parallel and/or orthogonal to the local feature orientations. To facilitate regular and directional spacing of dots, we introduce the notion of a structure grid, which is extracted from the smoothed feature orientation field. We represent a structure grid as a 2D texture and develop an efficient construction algorithm that outperforms conventional Lloyd’s method in terms of the rigor of dot alignment. Moreover, the criss-crossing nature of a structure grid allows for the inclusion of line primitives, providing effective description of dark tone. Given a structure grid, we determine the appropriate positions and attributes of primitives in the final illustration via rapid pixel-based primitive rendering. Experimental results show that our directional stippling method nicely reproduces features and tones of various input images.