26 research outputs found

    Compression of 3D models with NURBS

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    With recent progress in computing, algorithmics and telecommunications, 3D models are increasingly used in various multimedia applications. Examples include visualization, gaming, entertainment and virtual reality. In the multimedia domain 3D models have been traditionally represented as polygonal meshes. This piecewise planar representation can be thought of as the analogy of bitmap images for 3D surfaces. As bitmap images, they enjoy great flexibility and are particularly well suited to describing information captured from the real world, through, for instance, scanning processes. They suffer, however, from the same shortcomings, namely limited resolution and large storage size. The compression of polygonal meshes has been a very active field of research in the last decade and rather efficient compression algorithms have been proposed in the literature that greatly mitigate the high storage costs. However, such a low level description of a 3D shape has a bounded performance. More efficient compression should be reachable through the use of higher level primitives. This idea has been explored to a great extent in the context of model based coding of visual information. In such an approach, when compressing the visual information a higher level representation (e.g., 3D model of a talking head) is obtained through analysis methods. This can be seen as an inverse projection problem. Once this task is fullled, the resulting parameters of the model are coded instead of the original information. It is believed that if the analysis module is efficient enough, the total cost of coding (in a rate distortion sense) will be greatly reduced. The relatively poor performance and high complexity of currently available analysis methods (except for specific cases where a priori knowledge about the nature of the objects is available), has refrained a large deployment of coding techniques based on such an approach. Progress in computer graphics has however changed this situation. In fact, nowadays, an increasing number of pictures, video and 3D content are generated by synthesis processing rather than coming from a capture device such as a camera or a scanner. This means that the underlying model in the synthesis stage can be used for their efficient coding without the need for a complex analysis module. In other words it would be a mistake to attempt to compress a low level description (e.g., a polygonal mesh) when a higher level one is available from the synthesis process (e.g., a parametric surface). This is, however, what is usually done in the multimedia domain, where higher level 3D model descriptions are converted to polygonal meshes, if anything by the lack of standard coded formats for the former. On a parallel but related path, the way we consume audio-visual information is changing. As opposed to recent past and a large part of today's applications, interactivity is becoming a key element in the way we consume information. In the context of interest in this dissertation, this means that when coding visual information (an image or a video for instance), previously obvious considerations such as decision on sampling parameters are not so obvious anymore. In fact, as in an interactive environment the effective display resolution can be controlled by the user through zooming, there is no clear optimal setting for the sampling period. This means that because of interactivity, the representation used to code the scene should allow the display of objects in a variety of resolutions, and ideally up to infinity. One way to resolve this problem would be by extensive over-sampling. But this approach is unrealistic and too expensive to implement in many situations. The alternative would be to use a resolution independent representation. In the realm of 3D modeling, such representations are usually available when the models are created by an artist on a computer. The scope of this dissertation is precisely the compression of 3D models in higher level forms. The direct coding in such a form should yield improved rate-distortion performance while providing a large degree of resolution independence. There has not been, so far, any major attempt to efficiently compress these representations, such as parametric surfaces. This thesis proposes a solution to overcome this gap. A variety of higher level 3D representations exist, of which parametric surfaces are a popular choice among designers. Within parametric surfaces, Non-Uniform Rational B-Splines (NURBS) enjoy great popularity as a wide range of NURBS based modeling tools are readily available. Recently, NURBS has been included in the Virtual Reality Modeling Language (VRML) and its next generation descendant eXtensible 3D (X3D). The nice properties of NURBS and their widespread use has lead us to choose them as the form we use for the coded representation. The primary goal of this dissertation is the definition of a system for coding 3D NURBS models with guaranteed distortion. The basis of the system is entropy coded differential pulse coded modulation (DPCM). In the case of NURBS, guaranteeing the distortion is not trivial, as some of its parameters (e.g., knots) have a complicated influence on the overall surface distortion. To this end, a detailed distortion analysis is performed. In particular, previously unknown relations between the distortion of knots and the resulting surface distortion are demonstrated. Compression efficiency is pursued at every stage and simple yet efficient entropy coder realizations are defined. The special case of degenerate and closed surfaces with duplicate control points is addressed and an efficient yet simple coding is proposed to compress the duplicate relationships. Encoder aspects are also analyzed. Optimal predictors are found that perform well across a wide class of models. Simplification techniques are also considered for improved compression efficiency at negligible distortion cost. Transmission over error prone channels is also considered and an error resilient extension defined. The data stream is partitioned by independently coding small groups of surfaces and inserting the necessary resynchronization markers. Simple strategies for achieving the desired level of protection are proposed. The same extension also serves the purpose of random access and on-the-fly reordering of the data stream

    Object recognition in infrared imagery using appearance-based methods

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    Abstract unavailable please refer to PD

    Department of Defense Dictionary of Military and Associated Terms

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    The Joint Publication 1-02, Department of Defense Dictionary of Military and Associated Terms sets forth standard US military and associated terminology to encompass the joint activity of the Armed Forces of the United States. These military and associated terms, together with their definitions, constitute approved Department of Defense (DOD) terminology for general use by all DOD components

    Hero of Alexandria's Automata: a critical edition and translation, including a commentary on Book One

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    This thesis is a critical edition, with introduction, translation and partial commentary, of the Automata, a two-book mechanical treatise written by Hero of Alexandria (first century CE). It provides the first commentary on BOOK ONE, dealing with the construction of a mobile, as opposed to a stationary, automaton. The preface summarises the significance, aims and limitations of the work. The opening section gives a summary of some of the conventions and abbreviations used in the thesis, and is followed by a list of figures. The introduction provides a context for an informed reading of the text. It consists of six parts. Part One discusses the ‘Heronian question’, with particular attention to the chronology of the Automata and the Pneumatica. Part Two evaluates previous editions and translations, and summarises the main novelties of this study. Part Three assesses the manuscript tradition, including a stemmatic analysis of a large number of manuscripts. Part Four mainly discusses the various forms of the title of the treatise, which is reconstructed as Περὶ αὐτομάτων (On Automata). Greater uncertainty surrounds the heading of BOOK TWO, Περὶ στατῶν αὐτομάτων (On Stationary Automata), which may have been derived from Hero’s source, Philo of Byzantium (third-century BCE). Part Five focuses on the work itself. It starts with an overview of the structure of the text, with remarks on previous editorial practices. This is followed by a critical description of the contents of the treatise and by a discussion of the historical, literary and cultural background. This, in turn, allows for consideration of the performative context of Hero’s automata. Attention is then paid to the purpose and intended audience of the treatise, followed by an exploration of Hero’s relationship with his sources. A stylistic comparison with the Pneumatica sheds new light on Hero’s degree of originality, removing suspicions of interpolation. Finally, discussion turns to the status of the text. Internal inconsistencies are best explained as the result of incomplete authorial editing. Part Six addresses the principles of the edition. The text, apparatus criticus and translation form the centre of the thesis. To maximise readability, the layout of the English translation mirrors the layout of the Greek text. The elucidation of the manuscript sigla and abbreviations used in the apparatus criticus precedes the text. The commentary is mainly philological and text-critical in nature. However, it also addresses stylistic, interpretive and reconstructive issues, without failing to consider the oldest manuscript diagrams. Following the commentary are six appendixes: (1) a concordance of editions; (2) addenda et corrigenda to Schmidt’s edition; (3) three stemmata codicum; (4) illustrations; (5) a review of Masià (2015); (6) an index of technical terms. Appendix (4) includes manuscript diagrams and reconstruction drawings of the mobile automaton. The thesis closes with a bibliography

    Cryptography in a quantum world

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    Sound Knowledge: Music and Science in London, 1789-1851

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    What does it mean to hear scientifically? What does it mean to see musically? This volume uncovers a new side to the long nineteenth century in London, a hidden history in which virtuosic musical entertainment and scientific discovery intersected in remarkable ways. Sound Knowledge examines how scientific truth was accrued by means of visual and aural experience, and, in turn, how musical knowledge was located in relation to empirical scientific practice. James Q. Davies and Ellen Lockhart gather work by leading scholars to explore a crucial sixty-year period, beginning with Charles Burney’s ambitious General History of Music, a four-volume study of music around the globe, and extending to the Great Exhibition of 1851, where musical instruments were assembled alongside the technologies of science and industry in the immense glass-encased collections of the Crystal Palace. Importantly, as the contributions show, both the power of science and the power of music relied on performance, spectacle, and experiment. Ultimately, this volume sets the stage for a new picture of modern disciplinarity, shining light on an era before the division of aural and visual knowledge

    Deployment and navigation of aerial drones for sensing and interacting applications

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    Existing research recognises the critical role played by Unmanned Aerial Vehicles (UAVs) (also referred to as drones) to numerous civilian applications. Typical drone applications include surveillance, wireless communication, agriculture, among many others. One of the biggest challenges is to determine the deployment and navigation of the drones to benefit the most for different applications. Many research questions have been raised about this topic. For example, drone-enabled wildlife monitoring has received much attention in recent years. Unfortunately, this approach results in significant disturbance to different species of wild animals. Moreover, with the capability of rapidly moving communication supply towards demand when required, the drone equipped with a base station, i.e., drone-cell, is becoming a promising solution for providing cellular networks to victims and rescue teams in disaster-affected areas. However, few studies have investigated the optimal deployments of multiple drone-cells with limited backhaul communication distances. In addition, the use of autonomous drones as flying interactors for many real-life applications has not been sufficiently discussed. With superior maneuverability, drone-enabled autonomous aerial interacting can potentially be used on shark attack prevention and animal herding. Nevertheless, previous studies of autonomous drones have not dealt with such applications in much detail. This thesis explores the solutions to all the mentioned research questions, with a particular focus on the deployment and navigation of the drones. First, we provide one of the first investigations into reducing the negative impacts of wildlife monitoring drones by navigation control. Second, we study the optimal placement of a group of drone-cells with limited backhaul communication ranges, aims to maximise the number of served users. Third, we propose a novel method named ‘drone shark shield’, which uses communicating autonomous drones to intervene and prevent shark attacks for protecting swimmers and surfers. Lastly, we introduce one of the first autonomous drone herding systems for mustering a large number of farm animals efficiently. Simulations have been conducted to verify the effectiveness of the proposed approaches. We believe that our findings in this thesis shed new light on the fundamental benefits of autonomous civilian drones

    16th Wildland Shrub Symposium Threats to Shrubland Ecosystem Integrity 2010 May 18-20 Logan, UT

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    Abstract: The 29 papers in this proceedings are divided into the main organized sessions of the 16th Wildland Shrub Symposium, including the plenary session to introduce the theme of threats to shrubland ecosystem integrity, impacts of energy development and reclamation on ecosystem function, invasive plant ecology. wildlife habitats: impacts and restoration opportunities, historical perspectives in shrublands, ecosystem threats due to fire in the Mojave Desert, and modeling and monitoring of shrubland ecosystems. An overarching goal of the symposium was to make linkages between research and management
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