Browsing by Author "Lu, Lin"

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    Fabricable Multi-Scale Wang Tiles
    (The Eurographics Association and John Wiley & Sons Ltd., 2022) Liu, Xiaokang; Li, Chenran; Lu, Lin; Deussen, Oliver; Tu, Changhe; Campen, Marcel; Spagnuolo, Michela
    Wang tiles, also known as Wang dominoes, are a jigsaw puzzle system with matching edges. Due to their compactness and expressiveness in representing variations, they have become a popular tool in the procedural synthesis of textures, height fields, 3D printing and representing other large and non-repetitive data. Multi-scale tiles created from low-level tiles allow for a higher tiling efficiency, although they face the problem of combinatorial explosion. In this paper, we propose a generation method for multi-scale Wang tiles that aims at minimizing the amount of needed tiles while still resembling a tiling appearance similar to low-level tiles. Based on a set of representative multi-scale Wang tiles, we use a dynamic generation algorithm for this purpose. Our method can be used for rapid texture synthesis and image halftoning. Respecting physical constraints, our tiles are connected, lightweight, independent of the fabrication scale, able to tile larger areas with image contents and contribute to "mass customization".
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    Fabricable Unobtrusive 3D-QR-Codes with Directional Light
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Peng, Hao; Liu, Peiqing; Lu, Lin; Sharf, Andrei; Liu, Lin; Lischinski, Dani; Chen, Baoquan; Jacobson, Alec and Huang, Qixing
    QR code is a 2D matrix barcode widely used for product tracking, identification, document management and general marketing. Recently, there have been various attempts to utilize QR codes in 3D manufacturing by carving QR codes on the surface of the printed 3D shape. Nevertheless, significant shape editing and modulation may be required to allow readability of the embedded 3D-QR-codes with good decoding accuracy. In this paper, we introduce a novel QR code 3D fabrication framework aimed at unobtrusive embedding of 3D-QR-codes in the shape hence introducing minimal shape modulation. Essentially, our method computes bi-directional carvings in the 3D shape surface to obtain the black-and-white QR pattern. By using a directional light source, the black-and-white QR pattern emerges as lighted and shadow casted blocks on the shape respectively. To account for minimal modulation and elusiveness, we optimize the QR code carving w.r.t. shape geometry, visual disparity and light source position. Our technique employs a simulation of lighting phenomena through carved modules on the shape to ensure adequate contrast of the printed 3D-QR-code.