Local feature amount calculating device, method of calculating local feature amount, corresponding point searching apparatus, and method of searching corresponding point
First Claim
1. A local feature amount calculating device that calculates a local feature amount of an image, the local feature amount calculating device comprising:
- a feature point near-field region extracting unit that extracts a feature point and a near-field region that is set near the feature point from the image;
a direction strength calculating unit that calculates a direction of each pixel located within the near-field region and a strength of the direction;
a main axis direction detecting unit that detects a main axis direction of the near-field region; and
a local feature amount calculating unit that acquires a local feature amount of the feature point by giving a vote of the strength of the direction of each pixel, which is calculated by the direction strength calculating unit, to a vote cell to which the pixel belongs out of vote cells of a rotated vote cell pattern that is acquired by rotating a reference vote cell pattern by an angle corresponding to the main axis direction along a corrected direction that is acquired by correcting the direction of the pixel that is calculated by the direction strength calculating unit in accordance with the main axis direction.
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Abstract
A local feature amount calculating device includes a local feature amount calculating unit that acquires a local feature amount of a feature point for each pixel by giving a vote of a strength of the direction of a pixel, which is calculated by a direction strength calculating unit, to a vote cell to which a pixel of interest belongs out of vote cells of a rotated vote cell pattern that is acquired by rotating a reference vote cell pattern by an angle corresponding to a main axis direction along a corrected edge gradient direction that is acquired by correcting an edge gradient direction of the pixel that is calculated by a direction strength calculating unit in accordance with the main axis direction.
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Citations
20 Claims
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1. A local feature amount calculating device that calculates a local feature amount of an image, the local feature amount calculating device comprising:
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a feature point near-field region extracting unit that extracts a feature point and a near-field region that is set near the feature point from the image; a direction strength calculating unit that calculates a direction of each pixel located within the near-field region and a strength of the direction; a main axis direction detecting unit that detects a main axis direction of the near-field region; and a local feature amount calculating unit that acquires a local feature amount of the feature point by giving a vote of the strength of the direction of each pixel, which is calculated by the direction strength calculating unit, to a vote cell to which the pixel belongs out of vote cells of a rotated vote cell pattern that is acquired by rotating a reference vote cell pattern by an angle corresponding to the main axis direction along a corrected direction that is acquired by correcting the direction of the pixel that is calculated by the direction strength calculating unit in accordance with the main axis direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A computer-implemented method of calculating a local feature amount in which the local feature amount of an image is calculated, the method comprising:
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extracting, using a processor, a feature point from the image; setting, using the processor, a near-field area near the feature point; calculating, using the processor, a direction of each pixel located within the near-field region; calculating, using the processor, a strength of the direction of each pixel located within the near-field area; detecting, using the processor, a main axis direction of the near-field area based on the direction of the plurality of pixels located within the near-field region and the strength of the direction; acquiring, using the processor, a rotated vote cell pattern by rotating a reference vote cell pattern by an angle corresponding to the main axis direction; acquiring, using the processor a corrected direction by correcting the direction of each pixel in accordance with the main axis direction; and acquiring, using the processor a local feature amount of the feature point for each pixel located within the near-field region by giving a vote of the strength of the direction of a pixel to a vote cell to which the pixel belongs out of vote cells of a rotated vote cell pattern along the corrected direction. - View Dependent Claims (18, 19, 20)
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17. A computer-implemented method of calculating a local feature amount in which the local feature amount of an image is calculated, the method comprising:
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extracting, using a processor, a feature point from the image; setting, using the processor, a near-field area near the feature point; calculating, using the processor, a direction of each pixel located within the near-field region; quantizing, using the processor, the direction of each pixel located within the near-field region; calculating, using the processor, a strength of the direction of each pixel located within the near-field area; generating, using the processor, a direction histogram by giving a vote of the strength of the direction of the pixel along the direction of the pixel that is quantized in the quantizing of the direction and detecting a direction in which a local maximum value of the direction histogram is included as the main axis direction of the near-field region; determining, using the processor, a vote cell to which the pixel belongs in the vote cell pattern corresponding to the main axis direction for each pixel located within the near-field area by referring to a vote cell pattern table in which a plurality of vote cell patterns acquired by rotating a reference vote cell pattern by a plurality of angles corresponding to a plurality of main axis directions detected in the generating of a direction histogram is stored; acquiring, using the processor, corrected directions corresponding to the main axis direction and the directions quantized in the quantizing of the direction by referring to a direction correcting table in which the corrected directions for the directions quantized in the quantizing of the direction are defined for each one of the plurality of main axis directions detected in the generating of a direction histogram and detecting of a direction for each pixel located within the near-term area; and acquiring, using the processor, a local feature amount of the feature point for each pixel located within the near-field region by giving a vote of the strength of the direction of a pixel to a vote cell determined in the determining of a vote cell along the corrected direction.
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Specification