Auflistung nach Autor:in "Koch, Wolfgang"
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- KonferenzbeitragExtended object and group tracking: a comparison of random matrices and random hypersurface models(INFORMATIK 2010. Service Science – Neue Perspektiven für die Informatik. Band 2, 2010) Baum, Marcus; Feldmann, Michael; Fränken, Dietrich; Hanebeck, Uwe D.; Koch, WolfgangBased on previous work of the authors, this paper provides a comparison of two different tracking methodologies for extended objects and group targets, where the true shape of the extent is approximated by an ellipsoid. Although both methods exploit usual sensor data, i.e., position measurements of varying scattering centers, the distinctions are a consequence of the different modeling of the extent as a symmetric positive definite random matrix on the one hand and an elliptic random hypersurface model on the other. Besides analyzing the fundamental assumptions and a comparison of the properties of these tracking methods, simulation results are presented based on a static tracking environment to highlight especially the differences in the update step for the extension estimate.
- KonferenzbeitragIntelligente Verarbeitung von Sensordaten(IT-Standards in der Agrar- und Ernährungswirtschaft – Fokus: Risiko- und Krisenmanagement, 2014) Koch, Wolfgang
- KonferenzbeitragKnowledge-aided multi-sensor data processing for maritime surveillance(INFORMATIK 2010. Service Science – Neue Perspektiven für die Informatik. Band 2, 2010) Battistello, Giulia; Koch, WolfgangMaritime Situational Awareness (MSA) is founded on the collection and processing of information from heterogeneous sources, including radars, Navigation Aids (Vessel Traffic Monitoring and Information Systems, Automatic Identification System, Long Range Identification and Tracking System, etc), airbased and space-based monitoring services (Earth Observation), and recentlyconceived passive sensors for maritime surveillance (SIGINT, passive HF/VHF/X band radars). Several strategies for optimally fusing two or more of these information data flows have been proposed for MSA applications. However, the exploitation of context information - i.e. the so-called Knowledge Base - has not yet been thoroughly formulated. This paper provides a preliminary overview of the potential strategies for “knowledge-based” Maritime Multi-Sensor Data Fusion.
- KonferenzbeitragMobile terminal tracking in urban scenarios using multipath propagation(INFORMATIK 2006 – Informatik für Menschen, Band 1, 2006) Algeier, Vadim; Demissie, Bruno; Koch, Wolfgang; Thomä, ReinerLocating mobile terminals is an important requirement not only for offering location based services but also for handling emergency cases of nonsubscribed users, and radio surveillance. We propose a blind localization approach which takes advantage of multipath propagation by using additional information about the known locations of the main scattering objects, e.g. buildings. This information is processed by means of a simple ray tracing technique based on a 2D geographic data base. We assume a single observation station equipped with multiple antennas which is able of estimating the directional and relative temporal structure of the received multipath components. Exploiting the parameters of the multipath components we propose a mobile terminal tracking algorithm based on particle filtering technique.
- KonferenzbeitragMultisensordatenfusion: Trends, Lösungen und Anwendungsfelder(Informatik 2005 – Informatik Live! Band 2, 2005) Koch, WolfgangMultisensordatenfusion leistet die zeitlich integrierende, Redundanzen ausnutzende Verarbeitung multisensorieller Daten zu Information höherer Qualität. Unter Nutzung verfügbaren Hintergrundwissens erstrebt sie die Erstellung umfassender, präziser, zeitnaher Lagebilder als Entscheidungs-/Handlungsgrundlage.
- KonferenzbeitragOut-of-sequence data processing for track-before-detect using dynamic programming(INFORMATIK 2011 – Informatik schafft Communities, 2011) Govaers, Felix; Yang, Rong; Lai, Hoe Chee; Teow, Loo Nin; Ng, Gee Wah; Koch, WolfgangIn the recent past, tracking applications increasingly develop towards distributed sensor scenarios. In many cases, such schemes must cope with low observable targets in cluttered environments. Furthermore, such a setup suffers from communication delays and timely delayed sensor data. However, Track-before-Detect methodologies are not suitable for processing time delayed data yet. In this paper, we propose a new extension to a Dynamic Programming Algorithm (DPA) approach for Trackbefore-Detect in distributed sensor systems. This extension enables the DPA to process time delayed sensor data directly. Such delay might appear because of varying delays in the installed communication links. The extended DPA is identical to the recursive standard DPA in case of all sensor data appear in the timely correct order. In an experimental study, we show that the derived algorithm can compensate all occurring time delays very well.
- KonferenzbeitragPixel-based classification method for detecting unhealthy regions in leaf images(INFORMATIK 2011 – Informatik schafft Communities, 2011) Madhogaria, Satish; Schikora, Marek; Koch, Wolfgang; Cremers, DanielIn this paper, we present a pixel-based, discriminative classification algorithm for automatic detection of unhealthy regions in leaf images. The algorithm is designed to distinguish image pixels as belonging to one of the two classes: healthy and unhealthy. The task is solved in three steps. First, we perform segmentation to divide the image into foreground and background. In the second step, support vector machine (SVM) is applied to predict the class of each pixel belonging to the foreground. And finally, we do further refinement by neighborhood-check to omit all falsely-classified pixels from second step. The results presented in this work are based on a model plant (Arabidobsis thaliana), which forms the ideal basis for the usage of the proposed algorithm in biological researches concerning plant disease control mechanisms.
- KonferenzbeitragThe PMHT: solutions for some of its problems(INFORMATIK 2006 – Informatik für Menschen, Band 1, 2006) Wieneke, Monika; Koch, WolfgangTracking multiple targets in a cluttered environment is a challenging task. The Probabilistic Multi-Hypothesis Tracker (PMHT) is an efficient approach to cope with it. Linearity in the number of targets and measurements is the main motivation for its continued study. Unfortunately, the PMHT has not yet shown its superiority in terms of a better track-lost statistics. Furthermore, the problem of track extraction is not satisfactorily solved. This work focuses on mitigating the PMHT's main problems and presents the integration of a sequential likelihood-ratio test for track extraction.
- KonferenzbeitragProbabilistic classification of disease symptoms caused by salmonella on arabidopsis plants(INFORMATIK 2010. Service Science – Neue Perspektiven für die Informatik. Band 2, 2010) Schikora, Marek; Schikora, Adam; Kogel, Karl-Heinz; Koch, Wolfgang; Cremers, DanielSeveral reports have linked food poisoning with the consumption of raw vegetables and fruits contaminated by Salmonella. Most studies suggested an extracellular lifestyle of Salmonella on plants. However, more recent studies show that Salmonella are also able to colonize the intracellular compartment of various plant tissues causing chlorosis and eventually death of infected organs. The aim of this work is to present a probabilistic classification algorithm for disease symptoms on Arabidopsis thaliana plant in order to improve the current biological research. The algorithm itself uses images of Arabidopsis thaliana leaves as input and consists of two steps. The first step is the detection of pixels belonging to a leaf. This is done with a globally optimal color segmentation method. The second step is realized with a probabilistic framework to classify each pixel. Finally a morbidity rate is computed based on the classification result.
- KonferenzbeitragRobust likelihood function for blind mobile terminal localization(INFORMATIK 2010. Service Science – Neue Perspektiven für die Informatik. Band 2, 2010) Algeier, Vadim; Thomä, Reiner; Koch, WolfgangThe focus of this contribution is put on the blind localization of mobile terminals in urban scenarios. The proposed localization method exploits multipath propagation, which is typical of urban terrain. It is assumed that each multipath component is characterized by its direction of arrival (DoA) and relative time of arrival (RToA) parameter. In essence the developed method compares the multipath parameters predicted by the ray tracing algorithm with those measured by the single observing station. In this context inevitably occur a multipath order problem, which is tackled in detail within a proposed likelihood function definition. The latter follows an approach known from the robust statistics. Its intention is to provide a robust and reliable position estimate having at hand minimum a priori information about system parameters.