Dr. rer. nat.

Hecker, Dirk

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Topic modelling for spatial insights: Uncovering space use from movement data

2024-08-01 , Andriyenko, Gennadiy , Andriyenko, Nathaliya , Hecker, Dirk

We present a novel approach to understanding space use by moving entities based on repeated patterns of place visits and transitions. Our approach represents trajectories as text documents consisting of sequences of place visits or transitions and applies topic modelling to the corpus of these documents. The resulting topics represent combinations of places or transitions, respectively, that repeatedly co-occur in trips. Visualisation of the results in the spatial context reveals the regions of place connectivity through movements and the major channels used to traverse the space. This enables understanding of the use of space as a medium for movement. We compare the possibilities provided by topic modelling to alternative approaches exploiting a numeric measure of pairwise connectedness. We have extensively explored the potential of utilising topic modelling by applying our approach to multiple real-world movement data sets with different data collection procedures and varying spatial and temporal properties: GPS road traffic of cars, unconstrained movement on a football pitch, and episodic movement data reflecting social media posting events. The approach successfully demonstrated the ability to uncover meaningful patterns and interesting insights. We thoroughly discuss different aspects of the approach and share the knowledge and experience we have gained with people who might be potentially interested in analysing movement data by means of topic modelling methods.

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Visual analytics for understanding spatial situations from episodic movement data

2012 , Andrienko, Natalia , Andrienko, Gennady , Stange, Hendrik , Liebig, Thomas , Hecker, Dirk

Continuing advances in modern data acquisition techniques result in rapidly growing amounts of georeferenced data about moving objects and in emergence of new data types.We define episodic movement data as a new complex data type to be considered in the research fields relevant to data analysis. In episodic movement data, position measurements may be separated by large time gaps, in which the positions of the moving objects are unknown and cannot be reliably reconstructed. Many of the existing methods for movement analysis are designed for data with fine temporal resolution and cannot be applied to discontinuous trajectories. We present an approach utilising Visual Analytics methods to explore and understand the temporal variation of spatial situations derived from episodic movement data b y means of spatio-temporal aggregation. The situations are defined in terms of the presence of moving objects in different places and in terms of flows (collective movements) between the places. The approach, which combines interactive visual displays with clustering of the spatial situations, is presented by example of a real dataset collected by Bluetooth sensors.

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Big Data 2.0 - mit synthetischen Daten KI-Systeme stärken

2023 , Hecker, Dirk , Voß, Angelika , Paass, Gerhard , Wirtz, Tim

Bei der Anwendung von Künstlicher Intelligenz (KI) sind fehlende Daten immer noch eine Kernherausforderung und die Kosten zur Beschaffung ein kritischer Faktor für die Wirtschaftlichkeit vieler Geschäftsmodelle. Synthetische, also künstlich generierte Daten bilden einen Ausweg. Ein vielversprechender Lösungsansatz besteht darin, für die Datensynthese selbst ein KI-Modell einzusetzen.

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The why and how of trustworthy AI

2022-09-03 , Schmitz, Anna , Akila, Maram , Hecker, Dirk , Poretschkin, Maximilian , Wrobel, Stefan

Artificial intelligence is increasingly penetrating industrial applications as well as areas that affect our daily lives. As a consequence, there is a need for criteria to validate whether the quality of AI applications is sufficient for their intended use. Both in the academic community and societal debate, an agreement has emerged under the term “trustworthiness” as the set of essential quality requirements that should be placed on an AI application. At the same time, the question of how these quality requirements can be operationalized is to a large extent still open. In this paper, we consider trustworthy AI from two perspectives: the product and organizational perspective. For the former, we present an AI-specific risk analysis and outline how verifiable arguments for the trustworthiness of an AI application can be developed. For the second perspective, we explore how an AI management system can be employed to assure the trustworthiness of an organization with respect to its handling of AI. Finally, we argue that in order to achieve AI trustworthiness, coordinated measures from both product and organizational perspectives are required.

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