6 S. M. LaValle: Virtual Reality
head, hands, or legs. Other possibilities include voice commands, heart rate, body
temperature, and skin conductance (are you sweating?).
First- vs. Third-person If you are reading this book, then you most likely
want to devel op VR systems or experiences. Pay close attention to this next point!
When a scientist designs an experiment for an organism, as shown in Figure 1.2,
then the separation is clear: The laboratory subject (organis m ) h as a first-person
experience, while the scientist is a third-person observer. The scient i st carefully
designs the VR system as part of an experiment that will help to resolve a sci entific
hypothesis. For example, how does turning off a few neuron s in a rat’s brain affect
its navigation ability? On the oth er hand, when engineers or developers construct
a VR system or experience, they are usually targeting themselves and people
like them. They feel perfectly comfortable m oving back and forth between being
the “scientist” and the “lab subject” while evaluating and refining their work.
As you will learn throughout this book, this is a bad idea! The creators of the
experience are h eavily biased by their desire for it to succeed without havin g to
redo their work. They also know what t he experience is supposed to mean or
accomplish, which provides a strong bias in comparison to a fresh subject. To
complicate matters further , the creator’s body will physically and mentally adapt
to whatever fl aws are present so that they may so o n becom e invisible. We have
seen these ki n d s of things before. Fo r example, it is hard to predict how others
will react to your own writin g. Also, it is usually harder to proofread your own
writing in com p ar i son to that of others. In the case of VR, these effects ar e much
stronger and yet elusive to the point that you must force yourself to pay attention
to them. Take gre at care when hijacking the senses t h at you have trusted all of
your life. This will most likely be uncharted ter r i t or y for you.
More real than reali ty? How “r eal ” should the VR experience be? It is tempt-
ing to try to make it match ou r physical world as closely as possible. This is
referred to in Section 10.1 as the universal simulation principle: Any interaction
mechanism in the real world can be simulated in VR. Our brains are most familiar
with these s et t ings, thereby making it seem most appropriate. Th i s philosophy has
dominated the video game industry at times, for exampl e, in the development of
highly realistic first-person shooter (F PS ) games that are beau t i fu ll y rendered on
increasingly ad vanced graphics cards. In spi t e of th i s, understand that extr em e ly
simple, cartoon-like environments can also be effective and even p r efer able. Ex-
amples appear throughout history, as discussed in Section 1.3.
As a VR exp e ri ence creator, think carefully about the task, goals, or d esi r ed
effect you want to have on the user. You have the opportunity to make the
experience better than reality. What will they be doing? Taking a mat h course?
Experiencing a live theatrical perfor m ance? Writing software? Designing a house?
Maintain ing a long-distance relationship? Playin g a game? Having a medi t at i o n
and relaxation session? Traveling to another place on Earth, or in the un i verse?
For each of these, think about how the realism requirements might vary. For