Direct estimation of image deformations using visual front-end operations with automatic scale selection
Tony LindebergTechnical report, Department of Numerical Analysis and Computing Science, Royal Institute of Technology, S-100 44 Stockholm, Sweden, Nov. 1994. (ISRN KTH NA/P--94/33--SE)
Shortened version in: Proc.~5th International Conference on Computer Vision, (Cambridge, MA), June 1995, pages 134-141. IEEE Computer Society Press.
AbstractThis article deals with the problem of estimating deformations of brightness patterns using visual front-end operations. Estimating such deformations constitutes an important subtask in several computer vision problems relating to image correspondence and shape estimation. The following subjects are treated: The problem of decomposing affine flow fields into simpler components is analysed in detail. A canonical parametrization is presented based on singular value decomposition, which naturally separates the rotationally invariant components of the flow field from the rotationally variant ones. A novel mechanism is presented for automatic selection of scale levels when estimating local affine deformations. This mechanism is expressed within a multi-scale framework where disparity estimates are computed in a hierarchical coarse-to-fine manner and corrected using iterative techniques. Then, deformation estimates are selected from the scales that minimize a certain normalized residual over scales. Finally, the descriptors so obtained serve as initial data for computing refined estimates of the local deformations.
Keywords: affine transformation, scale selection, image correspondence, optic flow, shape estimation, stereo, motion, texture, disparity, vergence, invariance, deformation, decomposition, singular value, second moment matrix, surface model, enforced consistency, visual front-end, scale-space, computer vision
PostScript: (Shortened version at ICCV'95)
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