Virtual reality (VR) technology is evolving rapidly, making it precarious to define
VR in terms of specific devices that may fall out of favor in a year or two. In
this book, we are concerned with fundamental principles that are less sensitive to
particular technologies and therefore survive the test of time. Our first challenge
is to consider what VR actually means, in a way that captures the most crucial
aspects in spite of rapidly changing technology. The concept must also be general
enough to encompass what VR is considered today and what we envision for its
future.
We start with two representative examples that employ current technologies:
1) A human having an experience of flying over virtual San Francisco by flapping
his own wings (Figure 1.1); 2) a mouse running on a freely rotating ball while
exploring a virtual maze that appears on a projection screen around the mouse
(Figure 1.2). We want our definition of VR to be broad enough to include these
examples and many more, which are coming in Section 1.2. This motivates the
following.