System and method providing improved head motion estimations for animation
First Claim
1. A computer-readable medium storing computer-executable instructions that, when executed on a computer, perform a method to estimate head motion between two images of a face, the method comprising operations of:
- identifying, on the computer, locations of a plurality of distinct facial features in the two images, the locations corresponding to a number of unknowns determined upon estimation of head motion, the number of unknowns being determined by a number of equations;
converting, on the computer, the identified locations into a set of physical face parameters based on the symmetry of the distinct facial features, the set of physical face parameters reducing the number of unknowns as compared to the number of equations used to determine the unknowns; and
estimating, on the computer, head motion from identified points in the two images, the identified points being based on the set of physical face parameters.
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Abstract
The system provides improved procedures to estimate head motion between two images of a face. Locations of a number of distinct facial features are identified in two images. The identified locations can correspond to the eye corners, mouth corners and nose tip. The locations are converted into as a set of physical face parameters based on the symmetry of the identified distinct facial features. The set of physical parameters reduces the number of unknowns as compared to the number of equations used to determine the unknowns. An initial head motion estimate is determined by: (a) estimating each of the set of physical parameters, (b) estimating a first head pose transform corresponding to the first image, and (c) estimating a second head pose transform corresponding to the second image.
The head motion estimate can be incorporated into a feature matching algorithm to refine the head motion estimation and the physical facial parameters.
In one implementation, an inequality constraint is placed on a particular physical parameter—such as a nose tip, such that the parameter is constrained within a predetermined minimum and maximum value. The inequality constraint is converted to an equality constraint by using a penalty function. Then, the inequality constraint is used during the initial head motion estimation to add additional robustness to the motion estimation.
53 Citations
28 Claims
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1. A computer-readable medium storing computer-executable instructions that, when executed on a computer, perform a method to estimate head motion between two images of a face, the method comprising operations of:
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identifying, on the computer, locations of a plurality of distinct facial features in the two images, the locations corresponding to a number of unknowns determined upon estimation of head motion, the number of unknowns being determined by a number of equations; converting, on the computer, the identified locations into a set of physical face parameters based on the symmetry of the distinct facial features, the set of physical face parameters reducing the number of unknowns as compared to the number of equations used to determine the unknowns; and estimating, on the computer, head motion from identified points in the two images, the identified points being based on the set of physical face parameters. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer-readable medium storing computer-executable instructions that, when executed on a computer perform a method to estimate head motion between two images of a face, the method comprising operations of:
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identifying, on the computer, locations of a plurality of distinct facial features in the two images, the locations corresponding to a number of unknowns determined upon estimation of head motion, the number of unknowns being determined by a number of equations; converting, on the computer, the locations into set of physical face parameters based on the symmetry of the identified distinct facial features, the set of physical face parameters reducing the number of unknowns as compared to the number of equations used to determine the unknowns; determining, on the computer, an initial estimation of head motion between the two images using the set of physical face parameters; and refining, on the computer, the estimation of head motion by incorporating the initial estimation into a feature matching algorithm. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A computer-readable medium storing computer-executable instructions that, when executed on a computer, performs a method to estimate motion between two images, the method comprising operations of:
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identifying, on the computer, locations of a plurality of distinct features in the two images, the locations corresponding to symmetrical features shared between the two images, the locations corresponding to a number of unknowns determined upon estimation of motion between the two images; converting, on the computer, the locations into a set of parameters based on the symmetry of the identified distinct features, the parameters reducing the number of unknowns as compared to a number of equations used to determine the unknowns; and estimating, on the computer, motion between the two images using the parameters. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification