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SIFT Flow: Dense Correspondence across Scenes and Its Applications. Ce Liu, Jenny Yuen, and Antonio Torralba, MIT PAMI 2011 (ECCV 2008) Presented by Han Hu, I-vision Lab. Ce Liu, Researcher at Microsoft Research New England Experience:
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SIFT Flow: Dense Correspondence across Scenes and Its Applications Ce Liu, Jenny Yuen, and Antonio Torralba, MIT PAMI 2011 (ECCV 2008) Presented by Han Hu, I-vision Lab
Ce Liu, Researcher at Microsoft Research New England Experience: 1995-2002 Bachelor and Master student in Automation, Tsinghua University. 2002-2003 Assistant Researcher, Microsoft Research Asia. 2003-2009 PhD student in MIT. Main Works: Face Analysis
Ce Liu, Researcher at Microsoft Research New England Experience: 1995-2002 Bachelor and Master student in Automation, Tsinghua University. 2002-2003 Assistant Researcher, Microsoft Research Asia. 2003-2009 PhD student in MIT. Main Works: Denoising and Super resolution
Ce Liu, Researcher at Microsoft Research New England Experience: 1995-2002 Bachelor and Master student in Automation, Tsinghua University. 2002-2003 Assistant Researcher, Microsoft Research Asia. 2003-2009 PhD student in MIT. Main Works: Recognition and Parsing
Ce Liu, Researcher at Microsoft Research New England Experience: 1995-2002 Bachelor and Master student in Automation, Tsinghua University. 2002-2003 Assistant Researcher, Microsoft Research Asia. 2003-2009 PhD student in MIT. Main Works: Motion Analysis
Image Correspondence (Object Level Matching) [Berg et al. CVPR’05]
How to establish dense scene correspondence? Input Support Before alignment
How to establish dense scene correspondence? Input Support Optical flow Flow visualization code
How to establish dense scene correspondence? Input Support Warping of optical flow
How to establish dense scene correspondence? Input Support SIFT flow Dense SIFT image (RGB = first 3 components of 128D SIFT)
How to establish dense scene correspondence? Warping of SIFT flow Dense SIFT image (RGB = first 3 components of 128D SIFT)
Dense SIFT Flow Dense SIFT image (RGB = first 3 components of 128D SIFT
Formulation • Energy function: Data term Small displacement bias Smoothness term p, q: grid coordinate, w: flow vector, u, v: x- and y-components, s1, s2: SIFT descriptors
How to solve it?(Dual-Layer Belief Propagation) Complexity: O(n2h4) O(n2h2)
Other Tricks to Speed Up(Coarse-to-Fine) Complexity: O(n2h2) O(n2logh)
Coarse-to-Fine vs. 1-level Matching • Computational Time • 31s (Coarse-to-Fine) vs. more than 2 hours (1-level) for 256x256 images • Energy Cost
How to Find Meaningful Image Pairs? Optical Flow: Dense Sampling in Time Sift Flow: Dense Sampling in the Space of All Images
Experiments and Applications • Video Retrieval • Motion Prediction from a Single Image • Motion Synthesis • Image Registration • Face Recognition • Scene Parsing • …
Motion Prediction from a Single Image Warped Motion Original Image Best Match and Temporal Motion Ground Truth
Motion Prediction Original Image Synthesized Sequence The top video match
Face Recognition ORL Database Compare with the-state-of-the-art
Scene Parsing RGB SIFT Query tree sky Annotation SIFT RGB SIFT flow road field Nearest neighbors car unlabeled [C. Liu et al, CVPR’09]
Scene Parsing Parsing Ground truth RGB SIFT Query Good matches higher weight; CRF tree sky Annotation SIFT RGB SIFT flow road field Warpednearest neighbors car unlabeled
Summary • Introduce a concept: Dense Scene Alignment • A basic tool for applications which need correspondences between images