@phdthesis{Trapp2013,
  author    = {Trapp, Matthias},
  title     = {Interactive rendering techniques for focus+context visualization of 3D geovirtual environments},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66824},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {This thesis introduces a collection of new real-time rendering techniques and applications for focus+context visualization of interactive 3D geovirtual environments such as virtual 3D city and landscape models. These environments are generally characterized by a large number of objects and are of high complexity with respect to geometry and textures. For these reasons, their interactive 3D rendering represents a major challenge. Their 3D depiction implies a number of weaknesses such as occlusions, cluttered image contents, and partial screen-space usage. To overcome these limitations and, thus, to facilitate the effective communication of geo-information, principles of focus+context visualization can be used for the design of real-time 3D rendering techniques for 3D geovirtual environments (see Figure). In general, detailed views of a 3D geovirtual environment are combined seamlessly with abstracted views of the context within a single image. To perform the real-time image synthesis required for interactive visualization, dedicated parallel processors (GPUs) for rasterization of computer graphics primitives are used. For this purpose, the design and implementation of appropriate data structures and rendering pipelines are necessary. The contribution of this work comprises the following five real-time rendering methods: • The rendering technique for 3D generalization lenses enables the combination of different 3D city geometries (e.g., generalized versions of a 3D city model) in a single image in real time. The method is based on a generalized and fragment-precise clipping approach, which uses a compressible, raster-based data structure. It enables the combination of detailed views in the focus area with the representation of abstracted variants in the context area. • The rendering technique for the interactive visualization of dynamic raster data in 3D geovirtual environments facilitates the rendering of 2D surface lenses. It enables a flexible combination of different raster layers (e.g., aerial images or videos) using projective texturing for decoupling image and geometry data. Thus, various overlapping and nested 2D surface lenses of different contents can be visualized interactively. • The interactive rendering technique for image-based deformation of 3D geovirtual environments enables the real-time image synthesis of non-planar projections, such as cylindrical and spherical projections, as well as multi-focal 3D fisheye-lenses and the combination of planar and non-planar projections. • The rendering technique for view-dependent multi-perspective views of 3D geovirtual environments, based on the application of global deformations to the 3D scene geometry, can be used for synthesizing interactive panorama maps to combine detailed views close to the camera (focus) with abstract views in the background (context). This approach reduces occlusions, increases the usage the available screen space, and reduces the overload of image contents. • The object-based and image-based rendering techniques for highlighting objects and focus areas inside and outside the view frustum facilitate preattentive perception. The concepts and implementations of interactive image synthesis for focus+context visualization and their selected applications enable a more effective communication of spatial information, and provide building blocks for design and development of new applications and systems in the field of 3D geovirtual environments.},
  language  = {en}
}
@article{ReinhardtMascherGueletal.2010,
  author    = {Reinhardt, Wolfgang and Mascher, Michael and G{\"u}l, Senol and Magenheim, Johannes},
  title     = {Integration eines Rapid-Feedback-Moduls in eine koaktive Lern- und Arbeitsumgebung},
  series = {Commentarii informaticae didacticae : (CID)},
  journal   = {Commentarii informaticae didacticae : (CID)},
  number    = {4},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {1868-0844},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64339},
  pages     = {53 -- 58},
  year      = {2010},
  abstract  = {Die Evaluierung von Lehrveranstaltungen hat in vielen Lehreinrichtungen eine lange Tradition. In diesen klassischen Evaluierungsszenarien werden einmalig pro Semester Umfrageb{\"o}gen an die Studierenden verteilt und anschließend manuell ausgewertet. Die Ergebnisse sind dann zumeist am Ende der Vorlesungszeit vorhanden und geben einen punktuellen Einblick in die Qualit{\"a}t der Lehrveranstaltung bis zum Zeitpunkt der durchgef{\"u}hrten Evaluation. In diesem Artikel stellen wir das Konzept des Rapid Feedback, seine Einsatzm{\"o}glichkeiten in universit{\"a}ren Lehrveranstaltungen und eine prototypische Integration in eine koaktive Lern- und Arbeitsumgebung vor.},
  language  = {de}
}
@phdthesis{Bickel2008,
  author    = {Bickel, Steffen},
  title     = {Learning under differing training and test distributions},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33331},
  school      = {Universit{\"a}t Potsdam},
  year      = {2008},
  abstract  = {One of the main problems in machine learning is to train a predictive model from training data and to make predictions on test data. Most predictive models are constructed under the assumption that the training data is governed by the exact same distribution which the model will later be exposed to. In practice, control over the data collection process is often imperfect. A typical scenario is when labels are collected by questionnaires and one does not have access to the test population. For example, parts of the test population are underrepresented in the survey, out of reach, or do not return the questionnaire. In many applications training data from the test distribution are scarce because they are difficult to obtain or very expensive. Data from auxiliary sources drawn from similar distributions are often cheaply available. This thesis centers around learning under differing training and test distributions and covers several problem settings with different assumptions on the relationship between training and test distributions-including multi-task learning and learning under covariate shift and sample selection bias. Several new models are derived that directly characterize the divergence between training and test distributions, without the intermediate step of estimating training and test distributions separately. The integral part of these models are rescaling weights that match the rescaled or resampled training distribution to the test distribution. Integrated models are studied where only one optimization problem needs to be solved for learning under differing distributions. With a two-step approximation to the integrated models almost any supervised learning algorithm can be adopted to biased training data. In case studies on spam filtering, HIV therapy screening, targeted advertising, and other applications the performance of the new models is compared to state-of-the-art reference methods.},
  language  = {en}
}
@phdthesis{Awad2010,
  author    = {Awad, Ahmed Mahmoud Hany Aly},
  title     = {A compliance management framework for business process models},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49222},
  school      = {Universit{\"a}t Potsdam},
  year      = {2010},
  abstract  = {Companies develop process models to explicitly describe their business operations. In the same time, business operations, business processes, must adhere to various types of compliance requirements. Regulations, e.g., Sarbanes Oxley Act of 2002, internal policies, best practices are just a few sources of compliance requirements. In some cases, non-adherence to compliance requirements makes the organization subject to legal punishment. In other cases, non-adherence to compliance leads to loss of competitive advantage and thus loss of market share. Unlike the classical domain-independent behavioral correctness of business processes, compliance requirements are domain-specific. Moreover, compliance requirements change over time. New requirements might appear due to change in laws and adoption of new policies. Compliance requirements are offered or enforced by different entities that have different objectives behind these requirements. Finally, compliance requirements might affect different aspects of business processes, e.g., control flow and data flow. As a result, it is infeasible to hard-code compliance checks in tools. Rather, a repeatable process of modeling compliance rules and checking them against business processes automatically is needed. This thesis provides a formal approach to support process design-time compliance checking. Using visual patterns, it is possible to model compliance requirements concerning control flow, data flow and conditional flow rules. Each pattern is mapped into a temporal logic formula. The thesis addresses the problem of consistency checking among various compliance requirements, as they might stem from divergent sources. Also, the thesis contributes to automatically check compliance requirements against process models using model checking. We show that extra domain knowledge, other than expressed in compliance rules, is needed to reach correct decisions. In case of violations, we are able to provide a useful feedback to the user. The feedback is in the form of parts of the process model whose execution causes the violation. In some cases, our approach is capable of providing automated remedy of the violation.},
  language  = {en}
}
@article{DrewsSchirmerMorisseetal.2013,
  author    = {Drews, Paul and Schirmer, Ingrid and Morisse, Marcel and Sagawe, Arno and Rolf, Arno},
  title     = {Reflexionsdialog mit DialogueMaps},
  series = {Commentarii informaticae didacticae : (CID)},
  journal   = {Commentarii informaticae didacticae : (CID)},
  number    = {5},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {1868-0844},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64983},
  pages     = {117 -- 123},
  year      = {2013},
  abstract  = {In einigen Bereichen der Informatiklehre ist es m{\"o}glich, die pers{\"o}nlichen Erfahrungen der Studierenden im Umgang mit Informationstechnik aufzugreifen und vor dem Hintergrund theoretischer Konzepte aus der Literatur gemeinsam mit ihnen zu reflektieren. Das hier vorgestellte Lehrkonzept des Reflexionsdialogs erstreckt sich {\"u}ber drei Seminartermine und vorbereitende Selbstlernphasen. Unterst{\"u}tzt wird das Konzept durch DialogueMaps, eine Software zur Visualisierung komplexer Sachverhalte und zur Unterst{\"u}tzung interaktiver Dialoge. Dieser Beitrag beschreibt die Hintergr{\"u}nde des Lehrkonzeptes, das Lehrkonzept selbst sowie die inhaltliche Ausgestaltung im Rahmen eines Mastermoduls „Computergest{\"u}tzte Kooperation".},
  language  = {de}
}
@article{LaengrichSchulze2015,
  author    = {L{\"a}ngrich, Matthias and Schulze, J{\"o}rg},
  title     = {Angewandte Output-Orientierung},
  series = {HDI 2014 : Gestalten von {\"U}berg{\"a}ngen},
  volume    = {2015},
  journal   = {HDI 2014 : Gestalten von {\"U}berg{\"a}ngen},
  number    = {9},
  editor    = {Schwill, Andreas and Schubert, Sigrid},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-80299},
  pages     = {93 -- 107},
  year      = {2015},
  abstract  = {Erstsemester-Studierende sind mit den Anforderungen des Lehr-/ Lernprozess einer Universit{\"a}t oder Fachhochschule noch nicht vertraut. Ihre Erwartungen orientieren sich vielmehr an ihrer bisherigen Lerngeschichte (Abitur, Fachabitur, o. {\"a}.). Neben den fachlichen Anforderungen des ersten Semesters m{\"u}ssen die Studierenden also auch Ver{\"a}nderungen im Lehr-/Lernprozess erkennen und bew{\"a}ltigen. Es wird anhand einer Output-orientierten informatischen Lehrveranstaltung aufgezeigt, dass sich aus deren strengen Anforderungen der Messbarkeit klare Kompetenzbeschreibungen ergeben, die besonders dem Orientierungsbed{\"u}rfnis Erstsemester-Studierender entgegenkommen.},
  language  = {de}
}
@phdthesis{Wist2011,
  author    = {Wist, Dominic},
  title     = {Attacking complexity in logic synthesis of asynchronous circuits},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-59706},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Most of the microelectronic circuits fabricated today are synchronous, i.e. they are driven by one or several clock signals. Synchronous circuit design faces several fundamental challenges such as high-speed clock distribution, integration of multiple cores operating at different clock rates, reduction of power consumption and dealing with voltage, temperature, manufacturing and runtime variations. Asynchronous or clockless design plays a key role in alleviating these challenges, however the design and test of asynchronous circuits is much more difficult in comparison to their synchronous counterparts. A driving force for a widespread use of asynchronous technology is the availability of mature EDA (Electronic Design Automation) tools which provide an entire automated design flow starting from an HDL (Hardware Description Language) specification yielding the final circuit layout. Even though there was much progress in developing such EDA tools for asynchronous circuit design during the last two decades, the maturity level as well as the acceptance of them is still not comparable with tools for synchronous circuit design. In particular, logic synthesis (which implies the application of Boolean minimisation techniques) for the entire system's control path can significantly improve the efficiency of the resulting asynchronous implementation, e.g. in terms of chip area and performance. However, logic synthesis, in particular for asynchronous circuits, suffers from complexity problems. Signal Transitions Graphs (STGs) are labelled Petri nets which are a widely used to specify the interface behaviour of speed independent (SI) circuits - a robust subclass of asynchronous circuits. STG decomposition is a promising approach to tackle complexity problems like state space explosion in logic synthesis of SI circuits. The (structural) decomposition of STGs is guided by a partition of the output signals and generates a usually much smaller component STG for each partition member, i.e. a component STG with a much smaller state space than the initial specification. However, decomposition can result in component STGs that in isolation have so-called irreducible CSC conflicts (i.e. these components are not SI synthesisable anymore) even if the specification has none of them. A new approach is presented to avoid such conflicts by introducing internal communication between the components. So far, STG decompositions are guided by the finest output partitions, i.e. one output per component. However, this might not yield optimal circuit implementations. Efficient heuristics are presented to determine coarser partitions leading to improved circuits in terms of chip area. For the new algorithms correctness proofs are given and their implementations are incorporated into the decomposition tool DESIJ. The presented techniques are successfully applied to some benchmarks - including 'real-life' specifications arising in the context of control resynthesis - which delivered promising results.},
  language  = {en}
}
@phdthesis{Lorenz2011,
  author    = {Lorenz, Haik},
  title     = {Texturierung und Visualisierung virtueller 3D-Stadtmodelle},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53879},
  school      = {Universit{\"a}t Potsdam},
  year      = {2011},
  abstract  = {Im Mittelpunkt dieser Arbeit stehen virtuelle 3D-Stadtmodelle, die Objekte, Ph{\"a}nomene und Prozesse in urbanen R{\"a}umen in digitaler Form repr{\"a}sentieren. Sie haben sich zu einem Kernthema von Geoinformationssystemen entwickelt und bilden einen zentralen Bestandteil geovirtueller 3D-Welten. Virtuelle 3D-Stadtmodelle finden nicht nur Verwendung als Mittel f{\"u}r Experten in Bereichen wie Stadtplanung, Funknetzplanung, oder L{\"a}rmanalyse, sondern auch f{\"u}r allgemeine Nutzer, die realit{\"a}tsnah dargestellte virtuelle St{\"a}dte in Bereichen wie B{\"u}rgerbeteiligung, Tourismus oder Unterhaltung nutzen und z. B. in Anwendungen wie GoogleEarth eine r{\"a}umliche Umgebung intuitiv erkunden und durch eigene 3D-Modelle oder zus{\"a}tzliche Informationen erweitern. Die Erzeugung und Darstellung virtueller 3D-Stadtmodelle besteht aus einer Vielzahl von Prozessschritten, von denen in der vorliegenden Arbeit zwei n{\"a}her betrachtet werden: Texturierung und Visualisierung. Im Bereich der Texturierung werden Konzepte und Verfahren zur automatischen Ableitung von Fototexturen aus georeferenzierten Schr{\"a}gluftbildern sowie zur Speicherung oberfl{\"a}chengebundener Daten in virtuellen 3D-Stadtmodellen entwickelt. Im Bereich der Visualisierung werden Konzepte und Verfahren f{\"u}r die multiperspektivische Darstellung sowie f{\"u}r die hochqualitative Darstellung nichtlinearer Projektionen virtueller 3D-Stadtmodelle in interaktiven Systemen vorgestellt. Die automatische Ableitung von Fototexturen aus georeferenzierten Schr{\"a}gluftbildern erm{\"o}glicht die Veredelung vorliegender virtueller 3D-Stadtmodelle. Schr{\"a}gluftbilder bieten sich zur Texturierung an, da sie einen Großteil der Oberfl{\"a}chen einer Stadt, insbesondere Geb{\"a}udefassaden, mit hoher Redundanz erfassen. Das Verfahren extrahiert aus dem verf{\"u}gbaren Bildmaterial alle Ansichten einer Oberfl{\"a}che und f{\"u}gt diese pixelpr{\"a}zise zu einer Textur zusammen. Durch Anwendung auf alle Oberfl{\"a}chen wird das virtuelle 3D-Stadtmodell fl{\"a}chendeckend texturiert. Der beschriebene Ansatz wurde am Beispiel des offiziellen Berliner 3D-Stadtmodells sowie der in GoogleEarth integrierten Innenstadt von M{\"u}nchen erprobt. Die Speicherung oberfl{\"a}chengebundener Daten, zu denen auch Texturen z{\"a}hlen, wurde im Kontext von CityGML, einem international standardisierten Datenmodell und Austauschformat f{\"u}r virtuelle 3D-Stadtmodelle, untersucht. Es wird ein Datenmodell auf Basis computergrafischer Konzepte entworfen und in den CityGML-Standard integriert. Dieses Datenmodell richtet sich dabei an praktischen Anwendungsf{\"a}llen aus und l{\"a}sst sich dom{\"a}nen{\"u}bergreifend verwenden. Die interaktive multiperspektivische Darstellung virtueller 3D-Stadtmodelle erg{\"a}nzt die gewohnte perspektivische Darstellung nahtlos um eine zweite Perspektive mit dem Ziel, den Informationsgehalt der Darstellung zu erh{\"o}hen. Diese Art der Darstellung ist durch die Panoramakarten von H. C. Berann inspiriert; Hauptproblem ist die {\"U}bertragung des multiperspektivischen Prinzips auf ein interaktives System. Die Arbeit stellt eine technische Umsetzung dieser Darstellung f{\"u}r 3D-Grafikhardware vor und demonstriert die Erweiterung von Vogel- und Fußg{\"a}ngerperspektive. Die hochqualitative Darstellung nichtlinearer Projektionen beschreibt deren Umsetzung auf 3D-Grafikhardware, wobei neben der Bildwiederholrate die Bildqualit{\"a}t das wesentliche Entwicklungskriterium ist. Insbesondere erlauben die beiden vorgestellten Verfahren, dynamische Geometrieverfeinerung und st{\"u}ckweise perspektivische Projektionen, die uneingeschr{\"a}nkte Nutzung aller hardwareseitig verf{\"u}gbaren, qualit{\"a}tssteigernden Funktionen wie z.~B. Bildraumgradienten oder anisotroper Texturfilterung. Beide Verfahren sind generisch und unterst{\"u}tzen verschiedene Projektionstypen. Sie erm{\"o}glichen die anpassungsfreie Verwendung g{\"a}ngiger computergrafischer Effekte wie Stilisierungsverfahren oder prozeduraler Texturen f{\"u}r nichtlineare Projektionen bei optimaler Bildqualit{\"a}t. Die vorliegende Arbeit beschreibt wesentliche Technologien f{\"u}r die Verarbeitung virtueller 3D-Stadtmodelle: Zum einen lassen sich mit den Ergebnissen der Arbeit Texturen f{\"u}r virtuelle 3D-Stadtmodelle automatisiert herstellen und als eigenst{\"a}ndige Attribute in das virtuelle 3D-Stadtmodell einf{\"u}gen. Somit tr{\"a}gt diese Arbeit dazu bei, die Herstellung und Fortf{\"u}hrung texturierter virtueller 3D-Stadtmodelle zu verbessern. Zum anderen zeigt die Arbeit Varianten und technische L{\"o}sungen f{\"u}r neuartige Projektionstypen f{\"u}r virtueller 3D-Stadtmodelle in interaktiven Visualisierungen. Solche nichtlinearen Projektionen stellen Schl{\"u}sselbausteine dar, um neuartige Benutzungsschnittstellen f{\"u}r und Interaktionsformen mit virtuellen 3D-Stadtmodellen zu erm{\"o}glichen, insbesondere f{\"u}r mobile Ger{\"a}te und immersive Umgebungen.},
  language  = {de}
}
@article{KehrerKelter2010,
  author    = {Kehrer, Timo and Kelter, Udo},
  title     = {Eine aufwandsbeschr{\"a}nkte Einf{\"u}hrung in die modellbasierte Softwareentwicklung},
  series = {Commentarii informaticae didacticae : (CID)},
  journal   = {Commentarii informaticae didacticae : (CID)},
  number    = {4},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {1868-0844},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64304},
  pages     = {23 -- 33},
  year      = {2010},
  abstract  = {Zusammenfassung: Game-based Learning und Edutainment sind aktuelle Schlagworte im Bereich der Hochschulausbildung. Zun{\"a}chst verbindet man damit die Integration einer Spiel- und Spaßkultur in die herk{\"o}mmlichen Lehrveranstaltungen wie Vorlesungen, {\"U}bungen, Praktika und Seminare. Die nachfolgenden Ausf{\"u}hrungen gehen einer genaueren Begriffsanalyse nach und untersuchen, ob Game-based Learning und Edutainment tats{\"a}chlich neuartige Unterrichtsformen erfordern oder neue didaktische {\"U}berlegungen in bestehendes Unterrichtsgeschehen bringen - oder ob es nicht doch an einigen Stellen „alter Wein in neuen Schl{\"a}uchen" ist.},
  language  = {de}
}
@phdthesis{Boeken2022,
  author    = {B{\"o}ken, Bj{\"o}rn},
  title     = {Improving prediction accuracy using dynamic information},
  doi       = {10.25932/publishup-58512},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-585125},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xii, 160},
  year      = {2022},
  abstract  = {Accurately solving classification problems nowadays is likely to be the most relevant machine learning task. Binary classification separating two classes only is algorithmically simpler but has fewer potential applications as many real-world problems are multi-class. On the reverse, separating only a subset of classes simplifies the classification task. Even though existing multi-class machine learning algorithms are very flexible regarding the number of classes, they assume that the target set Y is fixed and cannot be restricted once the training is finished. On the other hand, existing state-of-the-art production environments are becoming increasingly interconnected with the advance of Industry 4.0 and related technologies such that additional information can simplify the respective classification problems. In light of this, the main aim of this thesis is to introduce dynamic classification that generalizes multi-class classification such that the target class set can be restricted arbitrarily to a non-empty class subset M of Y at any time between two consecutive predictions. This task is solved by a combination of two algorithmic approaches. First, classifier calibration, which transforms predictions into posterior probability estimates that are intended to be well calibrated. The analysis provided focuses on monotonic calibration and in particular corrects wrong statements that appeared in the literature. It also reveals that bin-based evaluation metrics, which became popular in recent years, are unjustified and should not be used at all. Next, the validity of Platt scaling, which is the most relevant parametric calibration approach, is analyzed in depth. In particular, its optimality for classifier predictions distributed according to four different families of probability distributions as well its equivalence with Beta calibration up to a sigmoidal preprocessing are proven. For non-monotonic calibration, extended variants on kernel density estimation and the ensemble method EKDE are introduced. Finally, the calibration techniques are evaluated using a simulation study with complete information as well as on a selection of 46 real-world data sets. Building on this, classifier calibration is applied as part of decomposition-based classification that aims to reduce multi-class problems to simpler (usually binary) prediction tasks. For the involved fusing step performed at prediction time, a new approach based on evidence theory is presented that uses classifier calibration to model mass functions. This allows the analysis of decomposition-based classification against a strictly formal background and to prove closed-form equations for the overall combinations. Furthermore, the same formalism leads to a consistent integration of dynamic class information, yielding a theoretically justified and computationally tractable dynamic classification model. The insights gained from this modeling are combined with pairwise coupling, which is one of the most relevant reduction-based classification approaches, such that all individual predictions are combined with a weight. This not only generalizes existing works on pairwise coupling but also enables the integration of dynamic class information. Lastly, a thorough empirical study is performed that compares all newly introduced approaches to existing state-of-the-art techniques. For this, evaluation metrics for dynamic classification are introduced that depend on corresponding sampling strategies. Thereafter, these are applied during a three-part evaluation. First, support vector machines and random forests are applied on 26 data sets from the UCI Machine Learning Repository. Second, two state-of-the-art deep neural networks are evaluated on five benchmark data sets from a relatively recent reference work. Here, computationally feasible strategies to apply the presented algorithms in combination with large-scale models are particularly relevant because a naive application is computationally intractable. Finally, reference data from a real-world process allowing the inclusion of dynamic class information are collected and evaluated. The results show that in combination with support vector machines and random forests, pairwise coupling approaches yield the best results, while in combination with deep neural networks, differences between the different approaches are mostly small to negligible. Most importantly, all results empirically confirm that dynamic classification succeeds in improving the respective prediction accuracies. Therefore, it is crucial to pass dynamic class information in respective applications, which requires an appropriate digital infrastructure.},
  language  = {en}
}