Method and system for detecting and tracking shopping carts from videos
First Claim
1. A method for detecting and tracking shopping carts, utilizing a position-dependent cart shape and motion model based on video images, comprising the following steps of:
- a) detecting and tracking motion blobs from the video images, wherein pixels within the same motion blob go through the same motion,b) detecting presence of carts within the detected motion blobs by collecting evidence from motions of pixels within the detected motion blobs,c) constructing a motion model of carts that characterizes the motion of passive objects pushed by humans,d) extracting motion features that characterize the motion of passive object by constructing a histogram of relative motions among points within the motion blobs,e) verifying presence of carts in the detected motion blobs based on the motion model of carts, andf) tracking the verified carts so that their individual identities can be maintained across the video images,wherein the histogram captures characteristic rigid motion of a cart and passive motion of the cart relative to a person pushing the cart.
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Abstract
The present invention is a method and system for detecting and tracking shopping carts from video images in a retail environment. First, motion blobs are detected and tracked from the video frames. Then these motion blobs are examined to determine whether or not some of them contain carts, based on the presence or absence of linear edge motion. Linear edges are detected within consecutive video frames, and their estimated motions vote for the presence of a cart. The motion blobs receiving enough votes are classified as cart candidate blobs. A more elaborate model of passive motions within blobs containing a cart is constructed. The detected cart candidate blob is then analyzed based on the constructed passive object motion model to verify whether or not the blob indeed shows the characteristic passive motion of a person pushing a cart. Then the finally-detected carts are corresponded across the video frames to generate cart tracks.
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Citations
16 Claims
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1. A method for detecting and tracking shopping carts, utilizing a position-dependent cart shape and motion model based on video images, comprising the following steps of:
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a) detecting and tracking motion blobs from the video images, wherein pixels within the same motion blob go through the same motion, b) detecting presence of carts within the detected motion blobs by collecting evidence from motions of pixels within the detected motion blobs, c) constructing a motion model of carts that characterizes the motion of passive objects pushed by humans, d) extracting motion features that characterize the motion of passive object by constructing a histogram of relative motions among points within the motion blobs, e) verifying presence of carts in the detected motion blobs based on the motion model of carts, and f) tracking the verified carts so that their individual identities can be maintained across the video images, wherein the histogram captures characteristic rigid motion of a cart and passive motion of the cart relative to a person pushing the cart. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for detecting and tracking shopping carts, utilizing a position-dependent cart shape and motion model based on video images, comprising:
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a) means for detecting and tracking motion blobs from the video images, wherein pixels within the same motion blob go through the same motion, b) means for detecting presence of carts within the detected motion blobs by collecting evidence from motions of pixels within the detected motion blobs, c) means for constructing a motion model of carts that characterizes the motion of passive objects pushed by humans, d) means for extracting motion features that characterize the motion of passive object by constructing a histogram of relative motions among points within the motion blobs, e) means for verifying presence of carts in the detected motion blobs based on the motion model of carts, and f) means for tracking the verified carts so that their individual identities can be maintained across the video images, wherein the histogram captures characteristic rigid motion of a cart and passive motion of the cart relative to a person pushing the cart. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification