System and method for machine vision object orientation measurement
First Claim
1. A method for measuring orientation parameters of a physical object comprising:
- acquiring a first image of the physical object, wherein at least a portion of the physical object is spherical;
selecting a first region of interest in the first image;
performing a circular random sample consensus operation on the first region of interest to detect a reference circle;
cropping the first region of interest to the image portion inside the reference circle;
performing a first semiellipse random sample consensus operation on the cropped first region of interest to detect a first primary semiellipse;
computing a first set of measured orientation parameters of the object from geometric parameters of the first primary semiellipse, wherein the first primary semiellipse indicates at least a portion of a first primary great circle discernible on the physical object;
whereby the orientation parameters of the physical object are measured from the acquired image.
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Abstract
Disclosed are methods and systems for measuring orientation parameters of spherical objects by image processing. Geometric shapes detected in a captured image are measured by generating and scoring models of the geometric shapes, where a high numerical score indicates a good match of the model to the image. The orientation parameters are computed from the geometric parameters measured from the image. A fast, precise, and accurate measurement requires generation and scoring be computationally efficient, meaning that many high-scoring models are generated in a short period of time. Disclosed are embodiments for a multistep measurement process for measuring the orientation parameters of an artificial hip joint from an x-ray image, measuring rotation of a basketball from video frame images, and navigating a spacecraft utilizing sunlight incident on a planetary body.
13 Citations
23 Claims
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1. A method for measuring orientation parameters of a physical object comprising:
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acquiring a first image of the physical object, wherein at least a portion of the physical object is spherical; selecting a first region of interest in the first image; performing a circular random sample consensus operation on the first region of interest to detect a reference circle; cropping the first region of interest to the image portion inside the reference circle; performing a first semiellipse random sample consensus operation on the cropped first region of interest to detect a first primary semiellipse; computing a first set of measured orientation parameters of the object from geometric parameters of the first primary semiellipse, wherein the first primary semiellipse indicates at least a portion of a first primary great circle discernible on the physical object; whereby the orientation parameters of the physical object are measured from the acquired image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A system for measuring the orientation of an object comprising:
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an image acquisition component wherein an image of the object is acquired, wherein at least a portion of the object is spherical; a central processing unit configured to execute instructions comprising; an image processing selection module configured to select a region of interest in the image, an image processing object identification module configured to perform a circular random sample consensus operation on the region of interest to detect a reference circle, to crop the region of interest to the image portion inside the reference circle, to perform a semiellipse random sample consensus operation on the cropped region of interest to detect a semiellipse, wherein the semiellipse indicates at least a portion of a first primary great circle discernible on the object, to compute a set of measured orientation parameters of the object from geometric parameters of the semiellipse. - View Dependent Claims (19, 20, 21, 22, 23)
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Specification