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Can a Fully Unconstrained Imaging Model be Applied Effectively to Central Cameras?
"... Traditional camera models are often the result of a com-promise between the ability to account for non-linearities in the image formation model and the need for a feasible num-ber of degrees of freedom in the estimation process. These considerations led to the definition of several ad hoc models tha ..."
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Traditional camera models are often the result of a com-promise between the ability to account for non-linearities in the image formation model and the need for a feasible num-ber of degrees of freedom in the estimation process. These considerations led to the definition of several ad hoc models that best adapt to different imaging devices, ranging from pinhole cameras with no radial distortion to the more com-plex catadioptric or polydioptric optics. In this paper we propose the use of an unconstrained model even in standard central camera settings dominated by the pinhole model, and introduce a novel calibration approach that can deal effectively with the huge number of free parameters associ-ated with it, resulting in a higher precision calibration than what is possible with the standard pinhole model with cor-rection for radial distortion. This effectively extends the use of general models to settings that traditionally have been ruled by parametric approaches out of practical considera-tions. The benefit of such an unconstrained model to quasi-pinhole central cameras is supported by an extensive exper-imental validation. 1.
Degeneracy of the Linear Seventeen-Point Algorithm for Generalized Essential Matrix
, 2010
"... In estimating motions of multi-centered optical systems using the generalized camera model, one can use the linear seventeen-point algorithm for obtaining a generalized essential matrix, the counterpart of the eight-point algorithm for the essential matrix of a pair of cameras. Like the eight-point ..."
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In estimating motions of multi-centered optical systems using the generalized camera model, one can use the linear seventeen-point algorithm for obtaining a generalized essential matrix, the counterpart of the eight-point algorithm for the essential matrix of a pair of cameras. Like the eight-point algorithm, the seventeen-point algorithm has degenerate cases. However, mechanisms of the degeneracy of this algorithm have not been investigated. We propose a method to find degenerate cases of the algorithm by decomposing a measurement matrix that is used in the algorithm into two matrices about ray directions and centers of projections. This decomposition method allows us not only to prove degeneracy of the previously known degenerate cases, but also to find a new degenerate configuration.
Can a Fully Unconstrained Imaging Model be Applied Effectively to Central Cameras?
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Author manuscript, published in "IEEE Conference on Computer Vision and Pattern Recognition (2008)" Minimal Solutions for Generic Imaging Models
, 2009
"... A generic imaging model refers to a non-parametric camera model where every camera is treated as a set of unconstrained projection rays. Calibration would simply be a method to map the projection rays to image pixels; such a mapping can be computed using plane based calibration grids. However, exist ..."
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A generic imaging model refers to a non-parametric camera model where every camera is treated as a set of unconstrained projection rays. Calibration would simply be a method to map the projection rays to image pixels; such a mapping can be computed using plane based calibration grids. However, existing algorithms for generic calibration use more point correspondences than the theoretical minimum. It has been well-established that non-minimal solutions for calibration and structure-from-motion algorithms are generally noise-prone compared to minimal solutions. In this work we derive minimal solutions for generic calibration algorithms. Our algorithms for generally central cameras use 4 point correspondences in three calibration grids to compute the motion between the grids. Using simulations we show that our minimal solutions are more robust to noise compared to non-minimal solutions. We also show very accurate distortion correction results on fisheye images. 1.
Author manuscript, published in "The 8th Workshop on Omnidirectional Vision, Camera Networks and Non-classical Cameras-
, 2008
"... Cone of view camera model using conformal geometric algebra for classic and panoramic image sensors. ..."
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Cone of view camera model using conformal geometric algebra for classic and panoramic image sensors.
WITH AUTOMATIC MODEL SELECTION – EXTENSION AND VALIDATION
"... and Validation ” I have examined the final electronic copy of this thesis for ..."
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and Validation ” I have examined the final electronic copy of this thesis for
4.2 Using Linear Calibration Objects............................... 3
"... pour obtenir le grade de Habilitation à diriger des Recherches de l’INSTITUT NATIONAL POLYTECHNIQUE DE GRENOBLE ..."
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pour obtenir le grade de Habilitation à diriger des Recherches de l’INSTITUT NATIONAL POLYTECHNIQUE DE GRENOBLE
