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3D Visual Phrases for Landmark Recognition. Qiang Hao , Rui Cai , Zhiwei Li, Lei Zhang, Yanwei Pang, Feng Wu Tianjin University, Tianjin 300072, P.R. China Microsoft Research Asia, Beijing 100080, P.R. China. Outline. Introduction 3D Visual Phrase Discovery
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3D Visual Phrases for Landmark Recognition QiangHao, RuiCai, ZhiweiLi, Lei Zhang, YanweiPang, FengWu Tianjin University, Tianjin 300072, P.R. China Microsoft Research Asia, Beijing 100080, P.R. China
Outline • Introduction • 3D Visual Phrase Discovery • 3D Visual Phrase Description • 3D Visual Phrase Detection • Evaluation • Conclusion and Future Work
Introduction Most existing work(BoW) • features extracted from irrelevant objects • treats the database images independently A 3D visual phrase is a triangular facet on the surface of a reconstructed 3D landmark model. • explicitly characterize the spatial structure of a 3D object • highly robust to projective transformations due to viewpoint changes.
3D Visual Phrase Discovery • 3D Landmark Reconstruction • 3D Point Selection • 3D Visual Phrase Generation • Multi-Scale 3D Visual Phrases
3D Visual Phrase Description • Visual Appearance • Geometric Structure
3D Visual Phrase Detection • Appearance-based Point Matching • Geometry-based Intra-Phrase Ranking • Graph-based Inter-Phrase Refinement
Conclusion and Future Work • In contrast to 2D visual phrases defined in 2D image planes, 3D visual phrases are derived from the physical space and explicitly characterize the 3D spatial structure of a landmark • Highly robust to viewpoint changes. • Geometric constraintsaredesired to afford to more relaxed point matching • Accelerate the algorithms, especially the point matching step.