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A tracking-by-detection framework is proposed that combines nearest-neighbor classification of bags of features, efficient subwin-dow search, and a novel feature selection and pruning method to achieve stability and plasticity in tracking targets of changing appearance. Experiments show that near-frame-rate performance is achieved (sans feature detection),(More)
We study the 3D reconstruction of plant roots from multiple 2D images. To meet the challenge caused by the delicate nature of thin branches, we make three innovations to cope with the sensitivity to image quality and calibration. First, we model the background as a harmonic function to improve the segmentation of the root in each 2D image. Second, we(More)
Offline tracking of visual objects is particularly helpful in the presence of significant occlusions, when a frame-by-frame, causal tracker is likely to lose sight of the target. In addition, the trajectories found by offline tracking are typically smoother and more stable because of the global optimization this approach entails. In contrast with previous(More)
Many computer vision systems approximate targets' shape with rectangular bounding boxes. This choice trades localization accuracy for efficient computation. We propose twisted window search, a strict generalization over rectangular window search, for the globally optimal localization of a target's shape. Despite its generality, we show that the new(More)
We present a nonparametric and efficient method for shape localization that improves on the traditional sub-window search in capturing the fine geometry of an object from a small number of feature points. Our method implies that the discrete set of features capture more appearance and shape information than is commonly exploited. We use the a-complex by(More)
" Architecture-driven synthesis techniques for mapping digital signal processing algorithms into silicon, " FSMs have a clear and unambiguous notion of a quantum of computation (one state transition), the problem reduces to determining what a quantum of computation is in the semantic model used to manage the concurrency and communication. This model could(More)
We propose new ideas and efficient algorithms towards bridging the gap between bag-of-features and constellation descriptors for image matching. Specifically, we show how to compute connections between local image features in the form of a critical net whose construction is repeatable across changes of viewing conditions or scene configuration. Arcs of the(More)
Motion synchrony, i.e., the coordinated motion of a group of individuals, is an interesting phenomenon in nature or daily life. Fish swim in schools, birds fly in flocks, soldiers march in platoons, etc. Our goal is to detect motion synchrony that may be present in the video data, and to track the group of moving objects as a whole. This opens the door to(More)