Special issue on virtual and mixed reality in culture and heritage.

The first paper, entitled "A Hybrid Augmented Reality Guide for Underwater Cultural Heritage Sites" (by J. Cejka, A. Zsíros and F. Liarokapis), presents a novel augmented reality guide for divers to present ancient lost buildings at underwater archeological sites. The paper discusses the design considerations and implementation details of the augmented reality smart glasses-based guide which provides visitors with context-aware information relevant to points of interest within their field of view. Acknowledgments We would like to thank the authors of all the submitted papers for considering our special issue and the Personal and Ubiquitous Computing journal as a potential publication venue for their research results. [Extracted from the article]