• Title/Summary/Keyword: Delaunay 삼각화

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3D Model Reconstruction Algorithm Using a Focus Measure Based on Higher Order Statistics (고차 통계 초점 척도를 이용한 3D 모델 복원 알고리즘)

  • Lee, Joo-Hyun;Yoon, Hyeon-Ju;Han, Kyu-Phil
    • Journal of Korea Multimedia Society
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    • v.16 no.1
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    • pp.11-18
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    • 2013
  • This paper presents a SFF(shape from focus) algorithm using a new focus measure based on higher order statistics for the exact depth estimation. Since conventional SFF-based 3D depth reconstruction algorithms used SML(sum of modified Laplacian) as the focus measure, their performance is strongly depended on the image characteristics. These are efficient only for the rich texture and well focused images. Therefore, this paper adopts a new focus measure using HOS(higher order statistics), in order to extract the focus value for relatively poor texture and focused images. The initial best focus area map is generated by the measure. Thereafter, the area refinement, thinning, and corner detection methods are successively applied for the extraction of the locally best focus points. Finally, a 3D model from the carefully selected points is reconstructed by Delaunay triangulation.

Print-Scan Resilient Curve Watermarking using B-Spline Curve Model and its 2D Mesh-Spectral Transform (B-스프라인 곡선 모델링 및 메시-스펙트럼 변환을 이용한 프린트-스캔에 강인한 곡선 워터마킹)

  • Kim, Ji-Young;Lee, Hae-Yeoun;Im, Dong-Hyuck;Ryu, Seung-Jin;Choi, Jung-Ho;Lee, Heung-Kyu
    • The KIPS Transactions:PartB
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    • v.15B no.4
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    • pp.307-314
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    • 2008
  • This paper presents a new robust watermarking method for curves that uses informed-detection. To embed watermarks, the presented algorithm parameterizes a curve using the B-spline model and acquires the control points of the B-spline model. For these control points, 2D mesh are created by applying Delaunay triangulation and then the mesh spectral analysis is performed to calculate the mesh spectral coefficients where watermark messages are embedded in a spread spectrum way. The watermarked coefficients are inversely transformed to the coordinates of the control points and the watermarked curve is reconstructed by calculating B-spline model with the control points. To detect the embedded watermark, we apply curve matching algorithm using inflection points of curve. After curve registration, we calculate the difference between the original and watermarked mesh spectral coefficients with the same process for embedding. By calculating correlation coefficients between the detected and candidate watermark, we decide which watermark was embedded. The experimental results prove the proposed scheme is more robust than previous watermarking schemes against print-scan process as well as geometrical distortions.