Designing a VR Experience

Design the User Objective

Making the user the focus of the design process is very important. In addition to the hardware, representation, and interface, the way in which the user uses the application must be addressed. The user should feel that the application has a purpose. Applications may be designed to entertain, educate, enlighten, visualize information, and so on, but there must be either a narrative or a task that can be carried out. In Aladdin's Magic Carpet Ride, the Disney design team conducted experiments and determined that people only tolerate undirected wandering in an environment for up to about two minutes [Pausch et al. 1996; Snoddy 1996]. After that, they want some direction. The initial hypothesis of the design group was that while people may generally want their entertainment to be packaged, this may not be the case in virtual reality. They found that this hypothesis was incorrect. Left undirected, people got bored and asked what they should do.

The type and amount of user interface needed also depends on the objective. If the experience is primarily a ride along or even a fly-through with little interaction with objects in the world, then a fairly simple user interface can be developed. For applications in which the user must be able to manipulate objects, especially multiple objects in conjunction with one another, the interface becomes more complicated. The more complicated the interactions and the interface, the more user testing must be done—another tradeoff.

Design the End of the Experience

How an experience ends varies greatly, depending on the type of experience. Some experiences are open ended; the user can work or play in the virtual world for an indefinite amount of time. Other experiences come to a definite close. Whether or not an experience has a concrete ending, the time a participant can remain physically immersed may be a fixed amount of time or the user may be allowed to remain in the environment continuously for as much time as desired. Neither open ended nor fixed experiences require a participant to be immersed uninterrupted for the entire duration. After expending their available time for a particular session, many VR applications will allow the participant to return later and pick up where they left off. For some persistent worlds, it may be possible for other participants to have entered and interacted with the world in the meantime.

The quintessential nonperpetual (fixed) experiences are the arcade pinball and videogame machines. Each time you experience these games you start at the beginning—zero score, level one—and work your way through as much of the experience as possible. When the last mistake is made (death, ball drop), the experience is over. Going out to a movie is of this same class; it starts at the beginning and after all the information is presented, it ends. If you return to experience it again, it restarts at the beginning. Thus, there are three ways such an experience may end: (1) time expiration (minutes are up), (2) terminal event (final ball drops), and (3) early user termination (user leaves from boredom).

Many public venue and demonstration VR applications are nonperpetual, limited-time experiences. The first two publicly exhibited Aladdin experiences lasted five minutes, during which time the player tried to accomplish a specific goal to win the game. Extra time was not given to allow the participant a chance to just explore the world. The Ford Galaxy VR experience created by Virtuality PLC for marketing automobiles was presented as a fixed-length narrative with a complete story (beginning, middle, and end). The user is prompted to enter the car. As they are driven to a destination, the features of the car are explained. When they reach the end of their journey, they exit the car and the VR system.

FIGURE 8-7

The Osmose VR application provides an ephemeral, surreal environment for artistic expression (Image courtesy of Char Davies). See color plate 31.

[Char Davies, Tree, from Osmose, 1995] †

[Digital frame captured in real-time
through head-mounted display during
live immersive journey/performance.]

Less narratively oriented applications can also be made to work within the confines of a limited-time experience. Char Davies's Osmose (FIGURE 8-7) is an artistic application that gives each user 15 minutes with which to explore the experience [Davies and Harrison 1996]. As it winds to a close, the experience shifts to a space designed to gently end the experience. The educational/scientific Pompeii application developed at the STUDIO lab at Carnegie Mellon University is another example where the participant is given a fixed amount of time to explore, this particular experience ending with the eruption of Mt. Vesuvius [Loeffler 1995]. The amount of time given (10 minutes) is not enough to explore the entire city, so the participant must choose which parts of the city to visit. In general, experiences for which throughput is important will be of fixed length.

The user can spend extended time in open ended experiences. Depending on the genre, this type of experience may or may not have a formal ending. For example, a scientific visualization application can be used over and over, with the scientist trying combinations of tools and exploring new data. Some experiences, particularly those with a strong narrative, may be lengthy but eventually do come to a conclusion. For example, a novel, text adventure (interactive fiction), or role-playing videogames where the player is given a task to accomplish may require 20 or more hours to complete, but eventually the last enigma is solved, the last page turned, and the experience is over. The Legend Quest game was a virtual reality experience of this type. There were a set number of quests each participant could undertake, and in each visit to the world they could attempt to accomplish one quest. While each encounter was a one-time event, the overall experience was made to be open ended by allowing the participant to store their vital statistics on a card they would keep and insert at the beginning of play each time.

Formal ending or not, these lengthy experiences often allow saving and restoring the state of the experience. The visualization tool parameters can be saved, the novel bookmarked, or the location of adventurer recorded. When the participant returns, they can pick up where they left off. The length of many experiences necessitates the ability to save the state of the world and is almost a defining characteristic of open ended experiences.

Denouement is the wrapping up of a story such that all the story's loose ends are bound up. For many exploratory (scientific or artistic) applications, it is up to the participant to figure out how everything fits together with their model of the world. So, in that respect, the denouement may come sometime significantly after the VR experience has ended. For more story-oriented experiences, it is up to the content creator to tie the ends together.