The examples shown in Figures 1.1 and 1.2 clearly fit the definition. Anyone donning a modern VR headset1.1 and enjoying a session should also be included. How far does our VR definition allow one to stray from the most common examples? Perhaps listening to music through headphones should be included. What about watching a movie at a theater? Clearly, technology has been used in the form of movie projectors and audio systems to provide artificial sensory stimulation. Continuing further, what about a portrait or painting on the wall? The technology in this case involves paints and a canvass. Finally, we might even want reading a novel to be considered as VR. The technologies are writing and printing. The stimulation is visual, but does not seem as direct as a movie screen and audio system. In this book, we not worry too much about the precise boundary of our VR definition. Good arguments could be made either way about some of these borderline cases, but it is more impotant to understand the key ideas for the core of VR. The boundary cases also serve as a good point of reference for historical perspective, which is presented in Section 1.3.
Steven M LaValle 2019-03-14