Publications

From 2014 (Clear Search)

2014
Publication Details
  • CHI Extended Abstracts 2014
  • Apr 26, 2014

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AirAuth is a biometric, gesture-based authentication system based on in-air gesture input. We describe the operations necessary to sample enrollment gestures and to perform matching for authentication, using data from a short range depth sensor. We present the results of two initial user studies. A first study was conducted to crowd source a simple gesture set for use in further evaluations. The results of our second study indicate that AirAuth achieves a very high Equal Error Rate (EER-)based accuracy of 96.6 % for simple gesture set and 100 % for user-specific gestures. Future work will encompass the evaluation of possible attack scenarios and obtaining qualitative user feedback on usability advantages of gesture-based authentication.
Publication Details
  • ACM ICMR 2014
  • Apr 1, 2014

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Motivated by scalable partial-duplicate visual search, there has been growing interest on a wealth of compact and efficient binary feature descriptors (e.g. ORB, FREAK, BRISK). Typically, binary descriptors are clustered into codewords and quantized with Hamming distance, which follows conventional bag-of-words strategy. However, such codewords formulated in Hamming space did not present obvious indexing and search performance improvement as compared to the Euclidean ones. In this paper, without explicit codeword construction, we explore to utilize binary descriptors as direct codebook indices (addresses). We propose a novel approach to build multiple index tables which parallelly check the collision of same hash values. The evaluation is performed on two public image datasets: DupImage and Holidays. The experimental results demonstrate the index efficiency and retrieval accuracy of our approach.

The Optimiser: monitoring and improving switching delays in video conferencing

Publication Details
  • ACM Workshop on Mobile Video (ACM MoVid)
  • Mar 18, 2014

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With the growing popularity of video communication systems, more people are using group video chat, rather than only one-to-one video calls. In such multi-party sessions, remote participants compete for the available screen space and bandwidth. A common solution is showing the current speaker prominently. Bandwidth limitations may not allow all streams to be sent at a high resolution at all times, especially with many participants in a call. This can be mitigated by only switching on higher resolutions when they are required. This switching encounters delays due to latency and the properties of encoded video streams. In this paper, we analyse and improve the switching delay of our video conferencing system. Our server-centric system offers a next-generation video chat solution, providing end-to-end video encoding. To evaluate our system we use a testbed that allows us to emulate different network conditions. We measure the video switching delay between three clients, each connected via different network profiles. Our results show that missing Intra-Frames in the transmission has a strong influence on the switching delay. Based on this, we provide an optimization mechanism that improves those delays by resending Intra-Frames.
http://dl.acm.org/citation.cfm?id=2579472

Multimedia Authoring and Annotation

Publication Details
  • International Journal on Multimedia Tools and Applications
  • Feb 28, 2014

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With the massive amount of captured multimedia, authoring is more relevant than ever. Multimedia content is available in many settings including the web, mobile devices, desktop applications, as well as games and interactive TV. The authoring and production of multimedia documents demands attention to many issues related to the structure and to the synchronization of the media components, to the specification of the document and of the interaction, to the roles of authors and end users, as well as issues concerning reuse and digital rights management. Several complementary approaches to support the authoring of multimedia documents have been reported in the literature, and in many cases they have been studied via authoring tools and applications. One aim of this special issue is to assess current approaches, tools and applications, discussing how they tackle the main issues relative to the process of authoring, as well as their limitations.
Publication Details
  • HotMobile 2014
  • Feb 26, 2014

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In this paper, we propose HiFi system which enables users to interact with surrounding physical objects. It uses coded light to encode position in an environment. By attaching a tiny light sensor on a user’s mobile device, the user can attach digital info to arbitrary static physical objects or retrieve/modify them anchored to these objects. With this system, a family member may attach a digital maintenance schedule to a fish tank or indoor plants, etc. In a store, a store manager may use such system to attach price tag, discount info and multimedia contents to any products and customers can get the attached info by moving their phone close to the focused product. Similarly, a museum can use this system to provide extra info of displayed items to visitors. Different from computer vision based systems, HiFi does not have requests on texture, bright illumination, etc. Different from regular barcode approaches, HiFi does not require extra physical attachments that may change an object’s native appearance. HiFi has much higher spatial resolution for distinguishing close objects or attached parts of the same object. As HiFi system can track a mobile device at 80 positions per second, it also has much faster response than any above listed system.
Publication Details
  • Fuji Xerox Technical Report, No. 23, 2014, pp. 34-42
  • Feb 20, 2014

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Video content creators invest enormous effort creating work that is in turn typically viewed passively. However, learning tasks using video requires users not only to consume the content but also to engage, interact with, and repurpose it. Furthermore, to promote learning with video in domains where content creators are not necessarily videographers, it is important that capture tools facilitate creation of interactive content. In this paper, we describe some early experiments toward this goal. A literature review coupled with formative field studies led to a system design that can incorporate a broad set of video-creation and interaction styles.