@inproceedings {mmsys.2013-03-15.9787518415,
	title = {Bagadus: an Integrated System for Arena Sports Analytics - a Soccer Case Study -},
	journal = {Proceedings of the 4th annual ACM conference on Multimedia Systems (MMSYS)},
	year = {2013},
	month = {March},
	pages = {48-59},
	publisher = {ACM},
	type = {Conference},
	abstract = {Sports analytics is a growing area of interest, both from a computer system view to manage the technical challenges and from a sport performance view to aid the development of athletes. In this paper, we present Bagadus, a prototype of a sports analytics application using soccer as a case study. Bagadus integrates a sensor system, a soccer analytics annotations system and a video processing system using a video camera array. A prototype is currently installed at Alfheim Stadium in Norway, and in this paper, we describe how the system can follow and zoom in on particular player(s). Next, the system will playout events from the games using stitched panorama video or camera switching mode and create video summaries based on queries to the sensor system. Further- more, we evaluate the system from a systems point of view, benchmarking different approaches, algorithms and trade-offs.},
	isbn = {978-1-4503-1894-5},
	author = {Halvorsen, P{\r a}l and S{\ae}grov, Simen and Mortensen, Asgeir and David Kai Christ {Kristensen} and Eichhorn, Alexander and Stenhaug, Magnus and Dahl, Stian and H{\r a}kon Kvale {Stensland} and Vamsidhar Reddy {Gaddam} and Griwodz, Carsten and Johansen, Dag},
	editor = {Zimmermann, Roger}
}
@inproceedings {Simula.simula.1650,
	title = {BAGADUS: an Integrated System for Soccer Analysis},
	journal = {Proceedings of the International Conference on Distributed Smart Cameras (ICDSC)},
	year = {2012},
	month = {October/November},
	publisher = {ACM/IEEE},
	type = {Conference},
	abstract = {In this demo, we present Bagadus, a prototype of a soccer analysis application which integrates a sensor system, soccer analytics annotations and video processing of a video camera array. The prototype is currently installed at Alfheim Stadium in Norway, and we demonstrate how the system can follow and zoom in on particular player(s), and playout events from the games using the stitched panorama video and/or the camera switching mode.},
	author = {Simen, S{\ae}grow and Eichhorn, Alexander and Emerslund, J{\o}rgen and H{\r a}kon Kvale {Stensland} and Griwodz, Carsten and Halvorsen, P{\r a}l}
}
@inproceedings {Simula.simula.932,
	title = {Characterizing the Response of Charge-Couple Device Digital Color Cameras},
	journal = {Proceedings of SPIE 8298, Sensors, Cameras, and Systems for Industrial and Scientific Applications XIII},
	volume = {82980G},
	year = {2012},
	publisher = {SPIE},
	type = {Conference},
	isbn = {yet unknown},
	doi = {10.1117/12.909298},
	author = {Slavkovikj, Viktor and Jon Yngve {Hardeberg} and Eichhorn, Alexander},
	editor = {Widenhorn, Ralf and Nguyen, Val{\'e}rie and Dupret, Antoine}
}
@inproceedings {Simula.simula.1644,
	title = {Evaluating Performance of Feature Extraction Methods for Practical 3D Imaging Systems},
	journal = {27th International Conference Image and Vision Computing New Zealand},
	year = {2012},
	month = {December},
	publisher = {ACM - International Conference Proceedings Series (ICPS)},
	type = {Conference},
	abstract = {Smart cameras are extensively used for multi-view capture and 3D rendering applications. To achieve high quality, such applications are required to estimate accurate position and orientation of the cameras (called as camera calibration-pose estimation). Traditional techniques that use checkerboard or special markers, are impractical in larger spaces. Hence, feature-based calibration (auto-calibration), is necessary. Such calibration methods are carried out based on features extracted and matched between stereo pairs or multiple cameras. Well known feature extraction methods such as SIFT (Scale Invariant Feature Transform), SURF (Speeded-Up Robust Features) and ORB (Oriented FAST and Rotated BRIEF) have been used for auto-calibration. The accuracy of auto-calibration is sensitive to the accuracy of features extracted and matched between a stereo pair or multiple cameras. In practical imaging systems, we encounter several issues such as blur, lens distortion and thermal noise that affect the accuracy of feature detectors. In our study, we investigate the behaviour of SIFT, SURF and ORB through simulations of practical issues and evaluate their performance targeting 3D reconstruction (based on epipolar geometry of a stereo pair). Our experiments are carried out on two real-world stereo image datasets of various resolutions. Our experimental results show significant performance differences between feature extractors\&$\#$39; performance in terms of accuracy, execution time and robustness to blur, lens distortion and thermal noise of various levels. Eventually, our study identifies suitable operating ranges that helps other researchers and developers of practical imaging solutions.},
	keywords = {Conference},
	author = {Dwarakanath, Deepak and Eichhorn, Alexander and Halvorsen, P{\r a}l and Griwodz, Carsten}
}
@inproceedings {cvmp2012,
	title = {A Fast Method for Global Depth-Map Extraction From Natural Images},
	journal = {Proceedings of the 9th European Conference on Visual Media Production},
	year = {2012},
	month = {December},
	pages = {59-65},
	publisher = {ACM},
	type = {Conference},
	address = {New York, NY, USA},
	abstract = {Dense depth-map extraction approaches either suffer from limited accuracy and robustness when run on natural images or from long computation times due to complex global optimizations. Recent improvements in massively parallel execution architectures found in today{\textquoteright}s graphics processing units motivated us to parallelize the global optimization process. In this article we present our analytical approach and a parallel implementation in OpenCL of a multi-label graph-cut algorithm. Our approach accomodates a third camera perspective through which we can improve occlusion handling in order to generate high quality depth maps. Through experiments on natural images we show that our implementation scales linearly and achieves close-to realtime performance.},
	isbn = {978-1-4503-1311-7},
	author = {Vamsidhar Reddy {Gaddam} and Eichhorn, Alexander and Jon Yngve {Hardeberg} and Shrestha, Raju},
	editor = {Grau, Oliver}
}
@inproceedings {drefereedinproceedingsreference.2012-12-10.5290080794,
	title = {Faster and More Accurate Feature-Based Calibration for Widely Spaced Camera Pairs},
	journal = {Digital Information and Communication Technology and it{\textquoteright}s Applications (DICTAP)},
	year = {2012},
	month = {May},
	pages = {87-92},
	publisher = {IEEE},
	type = {Conference},
	abstract = {The increasing demand for live multimedia systems in gaming, art and entertainment industries, has resulted in the development of multiview capturing systems that use camera arrays. We investigate sparse (widely spaced) camera arrays to capture scenes of large volume space. A vital aspect of such systems is camera calibration, which provides an understanding of the scene geometry used for 3D reconstruction. Traditional algorithms make use of a calibration object or identifiable markers placed in the scene, but this is impractical and inconvenient for large spaces. Hence, we take the approach of features-based calibration. Existing schemes based on SIFT (Scale Invariant Feature Transform), exhibit lower accuracy than marker-based schemes due to false positives in feature matching, variations in baseline (spatial displacement between the camera pair) and changes in viewing angle. Therefore, we propose a new method of SIFT feature based calibration, which adopts a new technique for the detection and removal of wrong SIFT matches and the selection of an optimal subset of matches. Experimental tests show that our proposed algorithm achieves higher accuracy and faster execution for larger baselines of up to \approx2 meters, for an object distance of \approx4.6 meters, and thereby enhances the usability and scalability of multi-camera capturing systems for large spaces.},
	keywords = {Conference},
	author = {Dwarakanath, Deepak and Eichhorn, Alexander and Griwodz, Carsten and Halvorsen, P{\r a}l and Dwarakanath, Deepak}
}
@inproceedings {Simula.simula.802,
	title = {Flicker Effects in Adaptive Video Streaming to Handheld Devices},
	journal = {Proceedings of the ACM International Multimedia Conference (ACM MM)},
	year = {2011},
	month = {Nov/Dec},
	pages = {463-472},
	publisher = {ACM},
	type = {Conference},
	abstract = {Streaming video over the Internet requires mechanisms that limit the streams{\textquoteright} bandwidth consumption within its fair share. TCP streaming guarantees this and provides lossless streaming as a side-effect. Adaptation by packet drop does not occur in the network, and excessive startup latency and stalling must be prevented by adapting the bandwidth consumption of the video itself. However, when the adaptation is performed during an ongoing session, it may influence the perceived quality of the entire video and result in improved or reduced visual quality of experience. We have in- vestigated visual artifacts that are caused by adaptive layer switching - we call them flicker effects - and present our results for handheld devices in this paper. We considered three types of flicker, namely noise, blur and motion flicker. The perceptual impact of flicker is explored through subjective assessments. We vary both the intensity of quality changes (amplitude) and the number of quality changes per second (frequency). Users{\textquoteright} ability to detect and their acceptance of variations in the amplitudes and frequencies of the quality changes are explored across four content types. Our results indicate that multiple fac- tors influence the acceptance of different quality variations. Amplitude plays the dominant role in delivering satisfactory video quality, while frequency can also be adjusted to relieve the annoyance of flicker artifacts.},
	author = {Ni, Pengpeng and Eg, Ragnhild and Eichhorn, Alexander and Griwodz, Carsten and Halvorsen, P{\r a}l},
	editor = {Sundaram, Hari and Feng, Wu-chi and Sebe, Nicu}
}
@inproceedings {Simula.simula.800,
	title = {Spatial Flicker Effect in Video Scaling},
	journal = {Proceedings of the International Workshop on Quality of Multimedia Experience (QoMEX)},
	year = {2011},
	month = {July},
	pages = {55-60},
	publisher = {IEEE},
	type = {Workshop},
	abstract = {Scalable video streaming may result in flicker effects - visual artifacts in video presentation due to adaptive layer switching. In our work, we have identified three types of flicker, noise, blur and motion flicker. Here, we investigate the blur and noise flicker, which are both related to the spatial domain. The perceptual impact of blur and noise flicker is explored through subjective assessments, focusing on acceptance of variations in the amplitudes and frequencies of the quality changes, across four content types. Our results indicate that the perception and acceptance of different layer variations are jointly influenced by multiple factors. When video scaling is required, frequency can be adjusted to relieve the annoyance of flicker artifacts, while amplitude still plays the dominant role in delivering satisfactory video quality. In addi- tion, contents with complex details are more affected by blur flicker than other contents. This difference is not observed for noise flicker.},
	isbn = {978-1-4577-1333-0},
	author = {Ni, Pengpeng and Eg, Ragnhild and Eichhorn, Alexander and Griwodz, Carsten and Halvorsen, P{\r a}l},
	editor = {Cristobal, Gabriel and Jacobs, An and Raake, Alexander}
}
@article {Simula.mpg.6,
	title = {Frequent Layer Switching for Perceived Quality Improvements of Coarse-Grained Scalable Video},
	journal = {ACM Multimedia Systems Journal},
	volume = {16},
	number = {3},
	year = {2010},
	month = {May},
	pages = {171-182},
	abstract = {Scalable video is an attractive option for adapting the bandwidth consumption of streaming video to the available bandwidth. Fine-grained scalability can adapt most closely to the available bandwidth, but this comes at the cost of a higher overhead compared to more coarse- grained videos. In the context of VoD streaming, we have therefore explored whether a similar adaptation to the available bandwidth can be achieved by performing layer switching in coarse-grained scalable videos. In this approach, enhancement layers of a video stream are swit- ched on and off to achieve any desired longer term band- width. We have performed three user studies, two using mobile devices and one using an HDTV display, to eval- uate the idea. In several cases, the far-from-obvious con- clusion is that layer switching is a viable way of achieving bit-rate savings and fine-grained bit-rate adaptation even for rather short times between layer switches, but it does, however, depend on scaling dimensions, content and dis- play device.},
	author = {Ni, Pengpeng and Eichhorn, Alexander and Griwodz, Carsten and Halvorsen, P{\r a}l}
}
@inproceedings {Simula.mpg.8,
	title = {Randomised Pair Comparison - an Economic and Robust Method for Audiovisual Quality Assessment},
	journal = {The 20th International Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV 2010)},
	year = {2010},
	pages = {63-68},
	publisher = {ACM},
	type = {Workshop},
	abstract = {Subjective quality perception studies with human observers are essential for multimedia system design. Such studies are known to be expensive and difficult to administer. They re- quire time, a detailed knowledge of experimental designs and a level of control which can often only be achieved in a lab- oratory setting. Hence, only very few researchers consider running subjective studies at all. In this paper we present Randomised Pair Comparison (r/pc), an easy-to-use, flexible, economic and robust exten- sion to conventional pair comparison methods. r/pc uses random sampling to select a unique and small subset of pairs for each assessor, thus separating session duration from the experimental design. With r/pc an experimenter can freely define the duration of sessions and balance between costs and accuracy of an experiment. On a realistic example study we show that r/pc is able to create stable results with an accuracy close to full factorial designs, yet much lower costs. We also provide initial evi- dence that r/pc can avoid unpleasant fatigue and learning effects which are common in long experiment sessions.},
	isbn = {978-1-4503-0043-8},
	author = {Eichhorn, Alexander and Ni, Pengpeng and Eg, Ragnhild},
	editor = {Dick C. A. {Bulterman}}
}
@inproceedings {Simula.ND.323,
	title = {Fine-Grained Scalable Streaming From Coarse-Grained Videos},
	journal = {International Workshop on Network and Operating Systems Support for Digital Audio and Video (NOSSDAV)},
	year = {2009},
	month = {June},
	pages = {103-108},
	publisher = {ACM},
	type = {Conference},
	abstract = {Scalable video is an attractive option for adapting the bandwidth consumption of streaming video to the available bandwidth. Fine-grained scalability can adapt most closely to the available bandwidth, but this comes at the cost of a high compression penalty. In the context of VoD streaming to mobile end systems, we have therefore explored whether a similar adaptation to the available bandwidth can be achieved by performing layer switching in coarse-grained scalable videos. In this approach, enhancement layers of a video stream are switched on and off to achieve any desired longer-term bandwidth. We performed user studies to evaluate the idea, and came to the far-from-obvious conclusion that layer switching is viable way for bit-rate savings and fine-grained bit-rate adaptation even for rather short times between layer switches.},
	isbn = {978-1-60558-433-1},
	author = {Ni, Pengpeng and Eichhorn, Alexander and Griwodz, Carsten and Halvorsen, P{\r a}l},
	editor = {Dongyan Xu Wei Tsa {Ooi}}
}
@inproceedings {Simula.ND.265,
	title = {Pick Your Layers Wisely - a Quality Assessment of H.264 Scalable Video Coding for Mobile Devices},
	journal = {IEEE International Conference on Communications},
	year = {2009},
	month = {June},
	pages = {1019-1025},
	publisher = {IEEE},
	type = {Conference},
	author = {Eichhorn, Alexander and Ni, Pengpeng},
	editor = {Akhavan, Hamid and K{\"u}hn, Paul and Fettweis, Gerhard and Kabacinski, Wojciech and St{\"u}ttgen, Heinrich}
}
@inproceedings {Simula.ND.125,
	title = {Middleware Abstractions for Cross-Layer Controlled Media Streaming},
	journal = {2nd Workshop on Middleware-Application Interaction (MAI{\textquoteright}08)},
	year = {2008},
	pages = {13-18},
	publisher = {ACM},
	type = {Workshop},
	abstract = {Efficiency, quality, and robustness of multimedia delivery over best-effort packet networks can be improved by advanced streaming protocols. This comes, however, at the cost of increased application complexity because existing solutions require close cooperation between transport layers and applications to perform effective adaptations. Media encoders have to become network-aware while transport layers need to consider certain properties of the data they deliver, such as the unequal importance of data units and their timing constraints. Today{\textquoteright}s adaptive streaming systems are developed jointly, customising encoders, protocols and surrounding code for a specific application. This heavily restricts the reuse of protocol implementations for other encoding formats, different application requirements and network environments. In order to enable reuse and simplify the integration of advanced streaming protocols into applications, we propose the Noja programming model for multimedia middleware layers. Noja{\textquoteright}s abstractions leverage protocol coordination and provide selective transparency features to effectively hide complexity, but expose necessary control options to application developers. Based on examples we show that Noja is applicable to a broad range of multimedia streaming applications and beyond that to data streaming applications in general.},
	author = {Eichhorn, Alexander},
	editor = {Hans P. {Reiser} and Kapitza, R{\"u}diger}
}
@inproceedings {Simula.ND.79,
	title = {Efficient Dependency Tracking in Packetised Media Streams},
	journal = {IEEE 9th Workshop on Multimedia Signal Processing},
	year = {2007},
	month = {Oct},
	pages = {139-142},
	publisher = {IEEE},
	type = {Workshop},
	abstract = {Scheduling and error control mechanisms for robust delivery of media streams over packet networks rely on distortion metrics to optimally allocate resources and protect streams from uncontrolled quality degradation. Current distortion metrics are accurate, but the actual distortion values are expensive to obtain. Therefore, distortion models often assume fixed dependency patterns and neglect fragmentation issues. While this decreases runtime complexity, it also limits the application of such models to special stream classes and network environments. In response, we present a practical, efficient and formatindependent framework to reason about dependencies in media streams. Based on correlation analysis we show that the estimations made by our framework match traditional distortion metrics for a number of H.264 encoded streams. Performance benchmarks indicate, that our framework is applicable at very low computational overheads.},
	isbn = {978-1-4244-1274-7},
	author = {Eichhorn, Alexander},
	editor = {Evripidis, Petrakis}
}
@inproceedings {Simula.ND.80,
	title = {Modelling Dependency in Media Streams},
	journal = {14th ACM International Conference on Multimedia},
	year = {2006},
	month = {Oct},
	pages = {941 - 950},
	publisher = {ACM},
	type = {Conference},
	abstract = {Expressing and analysing data dependency in multimedia streams is promising, since content-aware policies at a transport level would benefit from such services. In this paper we present a format-independent dependency model aimed at specifying, validating and reasoning about structural dependency in multimedia streams. Based on this model, we developed a universal dependency description language and a dependency validation service to serve as an infrastructure for content-aware transport layers. Driven by application knowledge, this special form of a cross-layer design enables lower layers to reason about the impact of data loss and drops during transmission while being unaware of the real data format. We outline, how this infrastructure can be used to build content-aware error protection policies and explain how applications need to specify dependency and prepare media streams in order to gain benefits from those policies. While costs and benefits of a dependency model are only quantifiable in conjunction with special policies, we report on the general worst-case costs of our model here.},
	isbn = {1-59593-447-2},
	author = {Eichhorn, Alexander},
	editor = {Zimmermann, Roger}
}
@inproceedings {Simula.ND.81,
	title = {Datenstr{\"o}me in Multimedialen Systemen, Merkmale Und Auswirkungen},
	journal = {NET.OBJECTDAYS - 8th Workshop on Multimedia Information and Communication Systems},
	year = {2002},
	month = {Oct},
	publisher = {tranSIT GmbH},
	type = {Workshop},
	address = {Ilmenau},
	abstract = {Multimediale Anwendungssysteme besitzen einen extremen Bedarf an Rechenressourcen und k{\"o}nnen vielfach nur unter hohen, f{\"u}r viele Anwendungsszenarien unakzeptablen Qualit{\"a}tseinschr{\"a}nkungen realisiert werden. Besonders deutlich wird dies in verteilten Szenarien mit kleineren, mobilen Systemen und drahtlosen Kommunikationsmedien, die sich aus diesem Grund heute noch vielen attraktiven Anwendungsfeldern verschlie{\ss}en. Ein wesentlicher Grund f{\"u}r den enormen Ressourcenhunger multimedialer Anwendungssysteme liegt im Volumen kontinuierlicher multimedialer Datenstr{\"o}me, die in derartigen Applikationen kommuniziert und verarbeitet werden und welches viele Terabit je Sekunde betragen kann. Dieser Beitrag bestimmt wesentliche Eigenschaften kontinuierlicher multimedialer Datenstr{\"o}me und identifiziert Implikationen f{\"u}r ad{\"a}quate Systemarchitekturen und Kommunikationsmodelle. Er argumentiert, dass Gr{\"u}nde f{\"u}r den heutigen Ressourcenhunger multimedialer Anwendungssysteme vielfach in den problemfremden Kommunikationsmodellen und Implementierungsstrategien bestehender IT-Infastrukturen zu suchen sind und liefert Hinweise f{\"u}r problemspezifische, effiziente Architekturen, Modelle und Mechanismen multimedialer Infrastrukturen.},
	isbn = {3-9808628-0-1},
	author = {Eichhorn, Alexander and Winfried E. {K{\"u}hnhauser}},
	editor = {Reschke, Dietrich}
}
@inproceedings {Simula.ND.82,
	title = {A Component-Based Architecture for Streaming Media},
	journal = {NET.OBJECTDAYS - 7th Workshop on Multimedia Information and Communication Systems},
	year = {2001},
	month = {Sep},
	publisher = {tranSIT GmbH},
	type = {Workshop},
	address = {Ilmenau},
	abstract = {This paper describes the design and implementation of a component based distributed multimedia application that was developed to investigate a new design principle for resource-efficient layered system architectures. In order to provide flexible and adaptable application scenarios, different applications are composed from four basic generic component types. Combining different component types with different types of interaction and locating them on different nodes of a distributed system then results in large distributed multimedia applications where each application has different types of sophisticated resource requirements. Beyond the scope of our test-bed we believe that this component-based architecture is well suited for general large scale streaming media applications such as video-conferencing and video on demand services.},
	isbn = {3-00-008419-3},
	author = {Eichhorn, Alexander and Winfried E. {K{\"u}hnhauser}},
	editor = {Reschke, Dietrich}
}
