Methods and devices for measuring object motion using camera images
First Claim
1. A method of measuring motion of an object using camera images, the method comprising:
- measuring a global optical flow field of a scene including a target object and a reference object captured as representations in an image sequence of the scene;
determining motion, relative to the scene, of a camera used to capture the image sequence by measuring an apparent, sub-pixel motion of the reference object with respect to an imaging plane of the camera, wherein determining the motion of the camera includes measuring the apparent, sub-pixel motion of the reference object within a frequency range of motion on a same order of magnitude as a frequency range of motion of the target object; and
calculating a corrected motion of the target object, corrected for the camera motion, based on the optical flow field of the scene and on the apparent, sub-pixel motion of the reference object with respect to the imaging plane of the camera.
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Abstract
A method and corresponding apparatus for measuring object motion using camera images may include measuring a global optical flow field of a scene. The scene may include target and reference objects captured in an image sequence. Motion of a camera used to capture the image sequence may be determined relative to the scene by measuring an apparent, sub-pixel motion of the reference object with respect to an imaging plane of the camera. Motion of the target object corrected for the camera motion may be calculated based on the optical flow field of the scene and on the apparent, sub-pixel motion of the reference object with respect to the imaging plane of the camera. Embodiments may enable measuring vibration of structures and objects from long distance in relatively uncontrolled settings, with or without accelerometers, with high signal-to-noise ratios.
48 Citations
44 Claims
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1. A method of measuring motion of an object using camera images, the method comprising:
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measuring a global optical flow field of a scene including a target object and a reference object captured as representations in an image sequence of the scene; determining motion, relative to the scene, of a camera used to capture the image sequence by measuring an apparent, sub-pixel motion of the reference object with respect to an imaging plane of the camera, wherein determining the motion of the camera includes measuring the apparent, sub-pixel motion of the reference object within a frequency range of motion on a same order of magnitude as a frequency range of motion of the target object; and calculating a corrected motion of the target object, corrected for the camera motion, based on the optical flow field of the scene and on the apparent, sub-pixel motion of the reference object with respect to the imaging plane of the camera. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A device for measuring the motion of an object using camera images, the device comprising:
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memory configured to store an image sequence of a scene including a target object and a reference object captured as representations in the image sequence; and a processor configured to; measure a global optical flow field of the scene from the image sequence of the scene; determine motion, relative to the scene, of a camera used to capture the image sequence by measuring an apparent, sub-pixel motion of the reference object with respect to an imaging plane of the camera by measuring the apparent, sub-pixel motion of the reference object within a frequency range of motion on a same order of magnitude as a frequency range of motion of the target object; and calculate a corrected motion of the target object, corrected for the camera motion, based on the optical flow field of the scene and on the apparent, sub-pixel motion of the reference object with respect to the imaging plane of the camera. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A method of measuring motion of an object using camera images, the method comprising:
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measuring a global optical flow field of a scene including a target object captured as representations in an image sequence of the scene; determining motion, relative to the scene, of a camera used to capture the image sequence by obtaining a motion measurement from an external sensor, the motion measurement being sub-pixel with respect to a pixel array of the camera, wherein determining motion of the camera includes obtaining the sub-pixel motion measurement from the external sensor within a frequency range of motion on a same order of magnitude as a frequency range of motion of the target object; and calculating a corrected motion of the target object, corrected for the camera motion, based on the optical flow field of the scene and the sub-pixel motion measurement from the external sensor. - View Dependent Claims (42, 43, 44)
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Specification