Matching Local Image Feature Descriptors in Image Analysis
First Claim
1. A computer-implemented method of matching features identified in first and second images captured from respective camera viewpoints related by an epipolar geometry, each identified feature being described by a local descriptor, the method comprising:
- using the epipolar geometry to define a geometrically-constrained region in the second image corresponding to a first feature in the first image represented by a first local descriptor;
comparing the first local descriptor with local descriptors of features in the second image, thereby determining respective measures of similarity between the first feature in the first image and the respective features in the second image;
identifying, from the features located in the geometrically-constrained region in the second image, (i) a geometric best match feature to the first feature, and (ii) a geometric next-best match feature to the first feature;
identifying, from any of the features in the second image, a global best match feature to the first feature;
performing a first comparison of the measures of similarity determined for the geometric best match feature and for the global best match feature, with respect to a first threshold;
performing a second comparison of the measures of similarity determined for the geometric best match feature and for the geometric next-best match feature, with respect to a second threshold; and
in dependence on whether the first and second thresholds are satisfied, selecting the geometric best match feature in the second image as an output match to the first feature in the first image.
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Abstract
A method of feature matching in images captured from camera viewpoints uses the epipolar geometry of the viewpoints to define a geometrically-constrained region in a second image corresponding to a first feature in a first image; comparing the local descriptor of the first feature with local descriptors of features in the second image to determine respective measures of similarity; identifying, from the features located in the geometrically-constrained region, (i) a geometric best match and (ii) a geometric next-best match to the first feature; identifying a global best match to the first feature; performing a first comparison of the measures of similarity for the geometric best match and the global best match; performing a second comparison of the measures of similarity for the geometric best match and the geometric next-best match; and, if thresholds are met, selecting the geometric best match feature in the second image.
9 Citations
20 Claims
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1. A computer-implemented method of matching features identified in first and second images captured from respective camera viewpoints related by an epipolar geometry, each identified feature being described by a local descriptor, the method comprising:
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using the epipolar geometry to define a geometrically-constrained region in the second image corresponding to a first feature in the first image represented by a first local descriptor; comparing the first local descriptor with local descriptors of features in the second image, thereby determining respective measures of similarity between the first feature in the first image and the respective features in the second image; identifying, from the features located in the geometrically-constrained region in the second image, (i) a geometric best match feature to the first feature, and (ii) a geometric next-best match feature to the first feature; identifying, from any of the features in the second image, a global best match feature to the first feature; performing a first comparison of the measures of similarity determined for the geometric best match feature and for the global best match feature, with respect to a first threshold; performing a second comparison of the measures of similarity determined for the geometric best match feature and for the geometric next-best match feature, with respect to a second threshold; and in dependence on whether the first and second thresholds are satisfied, selecting the geometric best match feature in the second image as an output match to the first feature in the first image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A data processing system for matching features identified in first and second images captured from respective camera viewpoints related by an epipolar geometry, each identified feature being described by a local descriptor, the data processing system comprising:
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a geometry unit configured to use the epipolar geometry to define a geometrically-constrained region in the second image corresponding to a first feature in the first image represented by a first local descriptor; a comparison unit configured to compare the first local descriptor with local descriptors of features in the second image thereby determining respective measures of similarity between the first feature in the first image and the respective features in the second image; and a match unit configured to; identify, from the features located in the geometrically-constrained region in the second image, (i) a geometric best match feature to the first feature, and (ii) a geometric next-best match feature to the first feature, identify, from any of the features in the second image, a global best match feature to the first feature, perform a first comparison of the measures of similarity determined for the geometric best match feature and for the global best match feature, with respect to a first threshold, perform a second comparison of the measures of similarity determined for the geometric best match feature and for the geometric next-best match feature, with respect to a second threshold, and in dependence on whether the first and second thresholds are satisfied, select the geometric best-match feature in the second image as an output match to the first feature in the first image.
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20. A non-transitory computer readable storage medium having stored thereon computer readable instructions that, when executed at a computer system, cause the computer system to perform a method of matching features identified in first and second images captured from respective camera viewpoints related by an epipolar geometry, each identified feature being described by a local descriptor, the method comprising:
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using the epipolar geometry to define a geometrically-constrained region in the second image corresponding to a first feature in the first image represented by a first local descriptor; comparing the first local descriptor with local descriptors of features in the second image, thereby determining respective measures of similarity between the first feature in the first image and the respective features in the second image; identifying, from the features located in the geometrically-constrained region in the second image, (i) a geometric best match feature to the first feature, and (ii) a geometric next-best match feature to the first feature; identifying, from any of the features in the second image, a global best match feature to the first feature; performing a first comparison of the measures of similarity determined for the geometric best match feature and for the global best match feature, with respect to a first threshold; performing a second comparison of the measures of similarity determined for the geometric best match feature and for the geometric next-best match feature, with respect to a second threshold; and in dependence on whether the first and second thresholds are satisfied, selecting the geometric best match feature in the second image as an output match to the first feature in the first image.
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Specification