Theory and applications of marker-based augmented reality: Licentiate thesis

Augmented Reality (AR) employs computer vision, image processing and computer graphics techniques to merge digital content into the real world. It enables real-time interaction between the user, real objects and virtual objects. In this work, we give a thorough overview of the theory and applications of AR. One of the challenges of AR is to align virtual data with the environment. A marker-based approach solves the problem using visual markers, e.g. 2D barcodes, detectable with computer vision methods. We discuss how different marker types and marker identification and detection methods affect the performance of the AR application and how to select the most suitable approach for a given application. Alternative approaches to the alignment problem do not require furnishing the environment with markers: detecting natural features occurring in the environment and using additional sensors. We discuss these as well as hybrid tracking methods that combine the benefits of several approaches. Besides the correct alignment, perceptual issues greatly affect user experience of AR. We explain how appropriate visualization techniques enhance human perception in different situations and consider issues that create a seamless illusion of virtual and real objects coexisting and interacting. Furthermore, we show how diminished reality can improve the visual appearance of AR and the interaction with real-world objects. Finally, we discuss practical issues of AR application development, identify potential application areas for augmented reality and speculate about the future of AR. In our experience, augmented reality is a profound visualization method for on-site 3D visualizations when the user's perception needs to be enhanced.