1,850 research outputs found

    Content-based Video Retrieval by Integrating Spatio-Temporal and Stochastic Recognition of Events

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    As amounts of publicly available video data grow the need to query this data efficiently becomes significant. Consequently content-based retrieval of video data turns out to be a challenging and important problem. We address the specific aspect of inferring semantics automatically from raw video data. In particular, we introduce a new video data model that supports the integrated use of two different approaches for mapping low-level features to high-level concepts. Firstly, the model is extended with a rule-based approach that supports spatio-temporal formalization of high-level concepts, and then with a stochastic approach. Furthermore, results on real tennis video data are presented, demonstrating the validity of both approaches, as well us advantages of their integrated us

    Content-based Video Retrieval

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    Image segmentation and feature extraction for recognizing strokes in tennis game videos

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    This paper addresses the problem of recognizing human actions from video. Particularly, the case of recognizing events in tennis game videos is analyzed. Driven by our domain knowledge, a robust player segmentation algorithm is developed real video data. Further, we introduce a number of novel features to be extracted for our particular application. Different feature combinations are investigated in order to find the optimal one. Finally, recognition results for different classes of tennis strokes using automatic learning capability of Hidden Markov Models (HMMs) are presented. The experimental results demonstrate that our method is close to realizing statistics of tennis games automatically using ordinary TV broadcast videos

    Content-based video indexing for the support of digital library search

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    Presents a digital library search engine that combines efforts of the AMIS and DMW research projects, each covering significant parts of the problem of finding the required information in an enormous mass of data. The most important contributions of our work are the following: (1) We demonstrate a flexible solution for the extraction and querying of meta-data from multimedia documents in general. (2) Scalability and efficiency support are illustrated for full-text indexing and retrieval. (3) We show how, for a more limited domain, like an intranet, conceptual modelling can offer additional and more powerful query facilities. (4) In the limited domain case, we demonstrate how domain knowledge can be used to interpret low-level features into semantic content. In this short description, we focus on the first and fourth item

    Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers

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    We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to 10510^5 rings. The rings have a circumference of 1 μ\mum, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current I\langle I \rangle in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of I\langle I \rangle.Comment: 5 pages, 5 figure

    Intrinsic and extrinsic decay of edge magnetoplasmons in graphene

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    We investigate intrinsic and extrinsic decay of edge magnetoplasmons (EMPs) in graphene quantum Hall (QH) systems by high-frequency electronic measurements. From EMP resonances in disk shaped graphene, we show that the dispersion relation of EMPs is nonlinear due to interactions, giving rise to intrinsic decay of EMP wavepacket. We also identify extrinsic dissipation mechanisms due to interaction with localized states in bulk graphene from the decay time of EMP wavepackets. We indicate that, owing to the unique linear and gapless band structure, EMP dissipation in graphene can be lower than that in GaAs systems.Comment: 5 page
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