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A Systematic Approach for Selecting Trajectories for Data Augmentation
Linnaeus University, Faculty of Technology, Department of computer science and media technology.
2026 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Trajectory data augmentation is a promising approach to mitigate data scarcity in machine learning applications, but its utility has been limited by the complexity of preserving spatio-temporal coherence. Although prior work demonstrated the viability of geometric perturbation, it relied on naive random selection, leaving a critical gap in understanding which trajectories should be augmented for maximal benefit. This thesis addresses this gap by developing a systematic and scalable framework to evaluate five systematic selection strategies: Outlierness, Diversity, Representativeness, Uncertainty, and Random selection. These strategies were rigorously tested across four datasets covering animal behavior (Foxes and Starkey), maritime traffic (AIS), and urban traffic (Car) using a suite of linear and non-linear machine learning models. As part of this evaluation, an Optuna-based hyperparameter optimization loop was integrated to empirically identify the best-performing augmentation parameters for each dataset within the explored search space. The results indicate that, while systematic selection is not a universal solution, it offers distinct advantages over the random baseline. Systematic strategies, particularly Outlierness and Uncertainty, demonstrated higher stability and were less prone to performance degradation observed with random sampling in dense datasets. However, the findings also reveal that the value of augmentation is strictly conditional. Visual analysis via UMAP demonstrates that while systematic augmentation successfully repairs topological fragmentation in sparse datasets, it can act as a corrupting noise signal in high-quality, dense datasets. Furthermore, the study identified physical limitations in high-velocity domains, where standard perturbation techniques lead to divergence in feature space. This research provides a practical evidence-based framework for practitioners, establishing that strategic data selection is not only an optimization detail, but can be the primary determinant of augmentation success.

Place, publisher, year, edition, pages
2026. , p. 39
Keywords [en]
trajectory data augmentation, systematic selection strategies, hyperparameter optimization, machine learning, trajectory classification, data scarcity, mobility analysis
National Category
Computer Sciences
Identifiers
URN: urn:nbn:se:lnu:diva-146239OAI: oai:DiVA.org:lnu-146239DiVA, id: diva2:2057524
Subject / course
Computer Science
Educational program
Software Technology Programme, Master Programme, 120 credits
Supervisors
Examiners
Available from: 2026-06-01 Created: 2026-05-05 Last updated: 2026-06-01Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
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  • Other locale
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Output format
  • html
  • text
  • asciidoc
  • rtf