We describe the development of software that is intended to enable decision makers (and their scientific advisors) to visualize uncertainties associated with the future global water balance. This is an important task because the future water balance is a function of numerous factors that are not precisely known, including the historical climatology, the model of potential evapotranspiration, the soil water holding capacity, and the global circulation models (GCMs) used to predict the effect of increased CO 2 in the atmosphere. In developing the software, we utilized the principles of usability engineering. In our case, we utilized six steps: prototype development, evaluation by domain experts, software revision, evaluation by usability experts, software revision, and evaluation by decision makers. Although this approach led to an improved piece of software, decision makers should have been involved earlier in the software design process, possibly at step two (instead of the domain experts). Decision makers found the notion of uncertainty discomforting, but their positive comments regarding the software suggest that it could prove beneficial, especially with improvements in spatial and temporal resolution. One interesting characteristic of our approach was the utilization of a wall-size display measuring 25 x 6 feet. The wall-size display engendered great interest, but determining whether it is truly effective will require a study that directly compares it with more traditional approaches.
In this paper, we report the results of a pilot study designed to evaluate the impact of signs as navigation aids in virtual worlds. Test subjects were divided into three groups (no aid, a dynamic electronic map, and signs) and asked to search a virtual building four times for six differently colored spheres. The spheres were in the same locations each time, and subjects were allowed to locate them in any order. A statistical analysis of the data revealed that on the first and second trials subjects took nearly four times as long to find the spheres with no aid present, compared to with maps and signs. We then compared only the sign and map conditions. Overall, subjects who navigated the world with the aid of signs were significantly faster than those who were provided with a map. While more research into the use of signs in virtual worlds is necessary, these results indicate that for at least some environments subjects are able to locate targets more quickly when using signs than maps.
In this paper, we explore the use of dynamically placed landmarks as navigation aids when users search a virtual world for target objects. Subjects were asked to search a virtual world four times for six red spheres. Eighty-six subjects participated in one of four conditions: no landmarks, statically placed landmarks, landmarks dynamically placed into the world at the subject's discretion that disappeared from trial to trial, and landmarks dynamically placed into the world at the subject's discretion that remained from trial to trial. An analysis of the experimental results revealed that dynamic landmarks which disappeared between trials had little impact on a subject's performance. However, when landmarks remained in the world from one trial to the next, subjects covered significantly less distance than those in the no landmark condition, and obtained similar performance to those in the static landmark condition. Results indicate that dynamically placed landmarks, which remain between visits, can serve as effective navigation aids in virtual worlds lacking obvious physical landmarks.
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