Browsing by Author "He, Ying"

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    Field-aligned Quadrangulation for Image Vectorization
    (The Eurographics Association and John Wiley & Sons Ltd., 2019) Wei, Guangshun; Zhou, Yuanfeng; Gao, Xifeng; Ma, Qian; Xin, Shiqing; He, Ying; Lee, Jehee and Theobalt, Christian and Wetzstein, Gordon
    Image vectorization is an important yet challenging problem, especially when the input image has rich content. In this paper, we develop a novel method for automatically vectorizing natural images with feature-aligned quad-dominant meshes. Inspired by the quadrangulation methods in 3D geometry processing, we propose a new directional field optimization technique by encoding the color gradients, sidestepping the explicit computing of salient image features. We further compute the anisotropic scales of the directional field by accommodating the distance among image features. Our method is fully automatic and efficient, which takes only a few seconds for a 400x400 image on a normal laptop. We demonstrate the effectiveness of the proposed method on various image editing applications.
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    Robust Computation of 3D Apollonius Diagrams
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Wang, Peihui; Yuan, Na; Ma, Yuewen; Xin, Shiqing; He, Ying; Chen, Shuangmin; Xu, Jian; Wang, Wenping; Eisemann, Elmar and Jacobson, Alec and Zhang, Fang-Lue
    Apollonius diagrams, also known as additively weighted Voronoi diagrams, are an extension of Voronoi diagrams, where the weighted distance is defined by the Euclidean distance minus the weight. The bisectors of Apollonius diagrams have a hyperbolic form, which is fundamentally different from traditional Voronoi diagrams and power diagrams. Though robust solvers are available for computing 2D Apollonius diagrams, there is no practical approach for the 3D counterpart. In this paper, we systematically analyze the structural features of 3D Apollonius diagrams, and then develop a fast algorithm for robustly computing Apollonius diagrams in 3D. Our algorithm consists of vertex location, edge tracing and face extraction, among which the key step is to adaptively subdivide the initial large box into a set of sufficiently small boxes such that each box contains at most one Apollonius vertex. Finally, we use centroidal Voronoi tessellation (CVT) to discretize the curved bisectors with well-tessellated triangle meshes. We validate the effectiveness and robustness of our algorithm through extensive evaluation and experiments. We also demonstrate an application on computing centroidal Apollonius diagram.