5,631 research outputs found

    Finding Temporally Consistent Occlusion Boundaries in Videos using Geometric Context

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    We present an algorithm for finding temporally consistent occlusion boundaries in videos to support segmentation of dynamic scenes. We learn occlusion boundaries in a pairwise Markov random field (MRF) framework. We first estimate the probability of an spatio-temporal edge being an occlusion boundary by using appearance, flow, and geometric features. Next, we enforce occlusion boundary continuity in a MRF model by learning pairwise occlusion probabilities using a random forest. Then, we temporally smooth boundaries to remove temporal inconsistencies in occlusion boundary estimation. Our proposed framework provides an efficient approach for finding temporally consistent occlusion boundaries in video by utilizing causality, redundancy in videos, and semantic layout of the scene. We have developed a dataset with fully annotated ground-truth occlusion boundaries of over 30 videos ($5000 frames). This dataset is used to evaluate temporal occlusion boundaries and provides a much needed baseline for future studies. We perform experiments to demonstrate the role of scene layout, and temporal information for occlusion reasoning in dynamic scenes.Comment: Applications of Computer Vision (WACV), 2015 IEEE Winter Conference o

    When Things Matter: A Data-Centric View of the Internet of Things

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    With the recent advances in radio-frequency identification (RFID), low-cost wireless sensor devices, and Web technologies, the Internet of Things (IoT) approach has gained momentum in connecting everyday objects to the Internet and facilitating machine-to-human and machine-to-machine communication with the physical world. While IoT offers the capability to connect and integrate both digital and physical entities, enabling a whole new class of applications and services, several significant challenges need to be addressed before these applications and services can be fully realized. A fundamental challenge centers around managing IoT data, typically produced in dynamic and volatile environments, which is not only extremely large in scale and volume, but also noisy, and continuous. This article surveys the main techniques and state-of-the-art research efforts in IoT from data-centric perspectives, including data stream processing, data storage models, complex event processing, and searching in IoT. Open research issues for IoT data management are also discussed

    Use of metaknowledge in the verification of knowledge-based systems

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    Knowledge-based systems are modeled as deductive systems. The model indicates that the two primary areas of concern in verification are demonstrating consistency and completeness. A system is inconsistent if it asserts something that is not true of the modeled domain. A system is incomplete if it lacks deductive capability. Two forms of consistency are discussed along with appropriate verification methods. Three forms of incompleteness are discussed. The use of metaknowledge, knowledge about knowledge, is explored in connection to each form of incompleteness

    DoNotBlameUsersforMisconfigurations

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    Similar to software bugs, configuration errors are also oneofthemajorcausesoftoday’ssystemfailures. Many configuration issues manifest themselves in ways similar to software bugs such as crashes, hangs, silent failures. It leaves users clueless and forced to report to developers for technical support, wasting not only users’ but also developers ’ precious time and effort. Unfortunately, unlike software bugs, many software developers takeamuchlessactive,responsibleroleinhandlingconfigurationerrorsbecause“theyareusers’faults.” This paper advocatesthe importancefor software developers to take an active role in handling misconfigurations. It also makes a concrete first step towards this goalbyprovidingtoolingsupporttohelpdevelopersimprove their configuration design, and harden their systems againstconfigurationerrors. Specifically,we build a tool, called SPEX, to automaticallyinferconfiguration requirements (referred to as constraints) from software sourcecode,andthenusetheinferredconstraintsto: (1) exposemisconfigurationvulnerabilities(i.e.,badsystem reactionsto configurationerrorssuch as crashes, hangs, silent failures); and (2) detect certain types of errorproneconfigurationdesignandhandling. We evaluate SPEX with one commercial storage system and six open-source server applications. SPEX automatically infers a total of 3800 constraints for more than2500configurationparameters. Basedontheseconstraints, SPEX further detects 743 various misconfiguration vulnerabilities and at least 112 error-prone constraints in the latest versions of the evaluated systems. To this day,364vulnerabilitiesand 80inconsistentcon-Permissiontomakedigitalorhardcopies ofpartorallofthis workfor personal or classroom use is granted without fee provided that copies arenotmadeordistributed forprofitorcommercialadvantage andthat copiesbearthisnoticeandthefullcitationonthefirstpage. Copyrights forthird-party components ofthisworkmustbehonored. Forallother uses, contact the Owner/Author. Copyright is held by the Owner/Author(s)
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