Precise definitions are elusive when it comes to the terms virtual reality (VR), augmented reality (AR), and mixed reality (MR). In common usage, VR tends to be associated with immersive head-mounted displays that fully supplant what the user can see, hear, and interact with. In contrast, AR tends to be associated with localized visual (and less commonly auditory) cues that exist as simple overlays on what the user is seeing or hearing via special glasses, a heads-up display, or even transparent display installation. Finally, MR is a more recent and less established term. Where...