Publications Search Results

Now showing 1 - 10 of 114
  • Publication
    Detecting Face Morphing Attacks by Analyzing the Directed Distances of Facial Landmarks Shifts
    ( 2019) ;
    Boller, Viola
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    Wainakh, Yaza
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    Braun, Andreas
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    Face morphing attacks create face images that are verifiable to multiple identities. Associating such images to identity documents lead to building faulty identity links, causing attacks on operations like border crossing. Most of previously proposed morphing attack detection approaches directly classified features extracted from the investigated image. We discuss the operational opportunity of having a live face probe to support the morphing detection decision and propose a detection approach that take advantage of that. Our proposed solution considers the facial landmarks shifting patterns between reference and probe images. This is represented by the directed distances to avoid confusion with shifts caused by other variations. We validated our approach using a publicly available database, built on 549 identities. Our proposed detection concept is tested with three landmark detectors and proved to outperform the baseline concept based on handcrafted and transferable CNN features.
  • Publication
    Designing a Self-Aware Jacket
    ( 2019)
    Rus, Silvia
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    Braun, Andreas
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    Smart textiles and garments promise intriguing new possibilities for the wearer. Integrated interaction can create new experiences and sensors can detect relevant information about the wearer. However, this poses an additional challenge for the designer of smart garments, about how to integrate these technologies. In this work, we want to investigate how human intuition and technical knowledge feed into the design of smart garments. Using a jacket that tracks its whereabouts as a use case, we have collected a dataset from 18 test subjects with varying technical knowledge, on what sensor patterns they would create on the garment. Using a specifically created simulation framework, we have evaluated the performance of the created sensor patterns. We observed that many participants intuitively create well-working patterns, while technical knowledge does not play a significant role in the resulting performance.
  • Publication
    Investigating large curved interaction devices
    ( 2019)
    Braun, Andreas
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    Zander-Walz, Sebastian
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    Majewski, Martin
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    Large interactive surfaces enable novel forms of interaction for their users, particularly in terms of collaborative interaction. During longer interactions, the ergonomic factors of interaction systems have to be taken into consideration. Using the full interaction space may require considerable motion of the arms and upper body over a prolonged period of time, potentially causing fatigue. In this work, we present Curved, a large-surface interaction device, whose shape is designed based on the natural movement of an outstretched arm. It is able to track one or two hands above or on its surface by using 32 capacitive proximity sensors. Supporting both touch and mid-air interaction can enable more versatile modes of use. We use image processing methods for tracking the user's hands and classify gestures based on their motion. Virtual reality is a potential use case for such interaction systems and was chosen for our demonstration application. We conducted a study with ten users to test the gesture tracking performance, as well as user experience and user preference for the adjustable system parameters.
  • Publication
    Performing indoor localization with electric potential sensing
    ( 2019) ; ; ;
    Große-Puppendahl, Tobias
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    Braun, Andreas
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    Location-based services or smart home applications all depend on an accurate indoor positioning system. Basically one divides these systems into token-based and token-free localization systems. In this work, we focus on the token-free system based on smart floor technology. Smart floors can typically be built using pressure sensors or capacitive sensors. However, these set-ups are often hard to deploy as mechanical or electrical features are required below the surface and even harder to replace when detected a sensor malfunctioning. Therefore we present a novel indoor positioning system using an uncommon form of passive electric field sensing (EPS), which detects the electric potential variation caused by body movement. The EPS-based smart floor set-up is easy to install by deploying a grid of passive electrode wires underneath any non-conductive surfaces. Easy maintenance is also ensured by the fact that the sensors are not placed underneath the surface, but on the side. Due to the passive measuring nature, low power consumption is achieved as opposed to active capacitive measurement. Since we do not collect image data as in visual-based systems and all sensor data is processed locally, we preserve the user's privacy. The proposed architecture achieves a high position accuracy and an excellent spatial resolution. Based on our evaluation conducted in our living lab, we measure a mean positioning error of only 12.7 cm.
  • Publication
    On Learning Joint Multi-biometric Representations by Deep Fusion
    ( 2019) ;
    Dimitrov, Kristiyan
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    Braun, Andreas
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    Multi-biometrics combines different biometric sources to enhance recognition, template protection, and indexing performances. One of the main challenges here is the need for joint discriminant feature representation of multi-biometric data. This is typically achieved by feature-level fusion, imposing limitations on the combinations of biometric characteristics and algorithms. Including multiple imaging sources within deep-learning networks was generally limited to multiple sources of images of the same physical object, e.g., multi-spectral object detection. Previous biometrics works were limited to use deep-learning to extract representations of single biometric characteristics. In contrast to that, our work studies creating representations of one identity by sampling different physical objects, i.e. biometric characteristics. We adapted three architectures successfully to produce and discuss jointly learned representations for different levels of correlated data, modalities, instances, and presentations. Our evaluation proved the applicability of jointly learning biometric representations, especially when the data correlation is low.
  • Publication
    Designing and evaluating safety services using depth cameras
    ( 2019)
    Mettel, Matthias Ruben
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    Alekseew, Michael
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    Stocklöw, Carsten
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    Braun, Andreas
    Not receiving help in the case of an emergency is one of the most common fears of older adults that live independently at home. Falls are a particularly frequent occurrence and often the cause of serious injuries. In the last years, various ICT solutions for supporting older adults at home have been developed. Based on sensors and services in a smart environment they provide a wide range of services. In this work we have designed and evaluated safety-related services, based on a single Microsoft Kinect that is installed in a user's home. We created two services to investigate the benefits and limitations of these solutions. The first is a fall detection service that registers falls in real-time, using a novel combination of static and dynamic skeleton tracking. The second is a fall prevention service that detects potentially dangerous objects in the walking path, based on scene analysis in a depth image. We conducted technical and user evaluations for both services, in order to get feedback on the feasibility, limitations, and potential future improvements.
  • Publication
    An experimental overview on electric field sensing
    Electric fields exist everywhere. They are influenced by living beings, conductive materials, and other charged entities. Electric field sensing is a passive capacitive measurement technique that detects changes in electric fields and has a very low power consumption. We explore potential applications of this technology and compare it to other measurement approaches, such as active capacitive sensing. Five prototypes have been created that give an overview of the potential use cases and how they compare to other technologies. Our results reveal that electric field sensing can be used for indoor applications as well as outdoor applications. Even a mobile usage is possible due to the low energy consumption of this technology.
  • Publication
    E-Textile Capacitive Electrodes: Fabric or Thread
    ( 2019)
    Rus, Silvia
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    Braun, Andreas
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    Back pain is one of the most common illnesses in Western civilizations. Office work and lack of motion can lead to deterioration over time. Many people already use seat cushions to improve their posture during work or leisure. In this work, we present an E-Textile cushion. This seat cushion is equipped with capacitive proximity sensors that track the proximity and motion of the sitting user and distinguish up to 7 postures. Giving a user immediate feedback on the posture can facilitate more healthy behavior. We evaluated a number of different electrode setups, materials, and classification methods, leading to a maximum accuracy of 97.1%.
  • Publication
    Minutiae-Based Gender Estimation for Full and Partial Fingerprints of Arbitrary Size and Shape
    Since fingerprints are one of the most widely deployed biometrics, accurate fingerprint gender estimation can positively affect several applications. For example, in criminal investigations, gender classification may significantly minimize the list of potential subjects. Previous work mainly offered solutions for the task of gender classification based on complete fingerprints. However, partial fingerprint captures are frequently occurring in many applications, including forensics and the fast growing field of consumer electronics. Due to its huge variability in size and shape, gender estimation on partial fingerprints is a challenging problem. Therefore, in this work we propose a flexible gender estimation scheme by building a gender classifier based on an ensemble of minutiae. The outputs of the single minutia gender predictions are combined by a novel adjusted score fusion approach to obtain an enhanced gender decision. Unlike classical solutions this allows to deal with unconstrained fingerprint parts of arbitrary size and shape. We performed investigations on a publicly available database and our proposed solution proved to significantly outperform state-of-the-art approaches on both full and partial fingerprints. The experiments indicate a reduction in the gender estimation error by 19.34% on full fingerprints and 28.33% on partial captures in comparison to previous work.
  • Publication
    An intuitive and personal projection interface for enhanced self-management
    ( 2018)
    Scheller, Doreen
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    Krajewski, Andrea
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    Coenen, Claudius
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    Siegmund, Dirk
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    Braun, Andreas
    Smart environments offer a high potential to improve intuitive and personal interactions in our everyday life. Nowadays, we often get distracted by interfaces and have to adapt ourselves to the technology, instead of the interfaces focusing on the human needs. Especially in work situations, it is important to focus on the essential in terms of goal setting and to have a far-reaching vision about ourselves. Particularly with regard to self-employment, challenges like efficient self-management, regulated work times and sufficient self-reflection arise. Therefore, we present 'Selv', a novel transportable device that is intended to increase user productivity and self-reflection by having an overview about obligations, targets and success. 'Selv' is an adaptive interface that changes its interactions in order to fit into the user's everyday routine. Our approach is using a pen on a projected interface. Adapting to our own feeling of naturalness 'Selv' learns usual interactions through handwriting recognition. In order to address users needs, it is more likely to built a mutual relationship and to convey a new feeling of an interface in a personal and natural way. This paper includes an elaborate concept and prototypical realization within the internet of things environment. We conclude with an evaluation of testings and improvements in terms of interactions and hardware.