Spatial Knowledge Systems

This study investigated the effects of nighttime lighting conditions and stress on the affective appraisal of a virtual environment (VE). The effective application of VEs in emotionally intense simulations requires precise control over their characteristics that affect the user's emotions and behavior. It is known that humans have an innate fear of darkness, which increases after exposure to stress and extrapolates to ecologically valid (immersive) VEs. This study investigated if the simulated level of illumination determines the affective appraisal of a VE, particularly after stress. Participants explored either a daytime or a nighttime version of a VE, after performing either an acute psychosocial stress task (Trier Social Stress Test, or TSST) or a relaxing control task. The affective qualities of the VE were appraised through the Russel and Pratt semantic questionnaire on the valence and arousal dimensions. Distress was assessed through free salivary cortisol, the state self-report scale from the Spielberger State-Trait Anxiety Inventory (STAI), and heart rate. In addition, memory for scenic details was tested through a yes-no recognition test. Free salivary cortisol levels, heart rates, and scores on the STAI all indicate that participants who were subjected to the stress task indeed showed signs of distress, whereas participants in the control group showed no signs of stress. The results of the semantic questionnaire and the recognition test showed no significant overall effect of time-of-day conditions on the affective appraisal of the VE or on the recognition of its details, even after prior stress. The experiences of users exploring the VE were not affected by the simulated lighting conditions, even after acute prior stress. Thus, lowering the illumination level in a desktop VE is not sufficient to elicit anxiety. Hence, desktop VE representations are different from immersive VE representations in this respect. This finding has implications for desktop VE representations that are deployed for serious gaming and training purposes.

Expectations of the functionality of 3D models of buildings on desktop computers are often high, but requirements used in design are generally incomplete, and insufficiently specified. One of the requirements usually omitted is that users of a model also give an affective appraisal of the building represented. The process of modeling and the display on a monitor cause modifications in the representation of the building that must be compensated by manipulations of the model to achieve a certain appraisal. It is proposed that this aspect is introduced, modeled and tested separately and systematically. A description of the use of 3D models for assessing public safety, in the project Visualisatie RandstadRail, is used as support for this approach.

We investigated if cybersickness has an effect on the affective appraisal of a virtual environment (VE). For many applications it is essential that users experience the simulated environment in a similar way as the corresponding real one. Navigation through VEs is known to negatively influence the physical well-being of observers by inducing cybersickness. Since people tend to misattribute their feelings to the environment they perceive, cybersicknesss may influence their affective appraisal of a VE. Participants passively watched a simulated walk through a VE, while the visual scene continuously performed a quasi-sinusoidal frontal roll oscillation. Immediately after the exposure, they reported their experienced level of cybersickness and assessed the environment on a semantic differential scale. People experiencing cybersickness rated the environment as less pleasant and more arousing, as compared to people with no symptoms. Thus, users suffering from cybersickness misattributed their unpleasant feelings to the affective qualities of the VE. Applications that rely on VEs to evoke the same emotional and affective user responses as their real equivalent should therefore minimise or account for the incidence of cybersickness.

The authors added task-relevant sounds to a computer-mediated instructor in-theloop virtual training for firefighter commanders in an attempt to raise the engagement and arousal of the users. Computer-mediated training for crew commanders should provide a sensory experience that is sufficiently intense to make the training viable and effective. In practice, sound is an important source of information for firefighters. During an evaluation of a soundless computer-mediated and instructor in-the-loop virtual training, both trainees and instructors frequently remarked that the lack of sound made the simulation less convincing and engaging. Research on entertainment games has shown that users may experience higher levels of presence, engagement, and arousal when sound is included in the simulations. The authors therefore hypothesized that the addition of task-relevant (informative) sounds to a virtual training would raise the engagement and arousal of the users, and the overall convincingness of the simulation. In this study, they included verisimilar and taskrelevant sounds in an instructor in-the-loop computer-mediated firefighter training and assessed how these sounds affect user experience. In contrast to the common belief of trainees and instructors, the authors find that merely adding task-relevant sounds does not necessarily increase the engagement and arousal of the users. The authors conclude that the physical presence of (and verbal communication with) the instructor probably distracted from the simulation, and an integral sound design involving mediated communication with a remotely present instructor may be required to resolve this problem.

We assessed the effects of the addition of dynamic visual elements and sounds to a levee patroller training game on the appraisal of the environment and weather conditions, the engagement of the users and their performance. Results show that the combination of visual dynamics and sounds best conveys the impression of severe weather conditions and most strongly influences the appraisal of the environment. Moderate effects on the engagement of the participants were found.

Interactive navigable 3D visualisations of built and natural environments have become commonplace in design and planning of urban environments and landscapes, and are regarded as potent prototyping and communication tools. In training applications, for instance for fire fighters, virtual environments displayed on desktop monitors or on projection screens are used to represent situations and scenarios that cannot be created in

It is well known that navigation through VEs may have a negative effect on the physical well-being of observers, by inducing cybersickness. In this study we investigated if cybersickness interacts with the appraisal of a simulated environment. Using the Half-Life 2 level editor we created a VE representing fictitious rural and urban areas. This environment was displayed by means of back projection onto a semi-transparent (frosted) screen, and was viewed from 1 m distance. For a 17 minute period, 32 subjects passively watched a walk through this VE, where the visual scene continuously performed a quasi-sinusoidally frontal roll oscillation. Immediately after the exposure, the remaining subjects filled out an appraisal questionnaire rating the environment on 4 dimensions: arousing-sleepy, pleasant-unpleasant, exciting-gloomy and distressing-relaxing. Two subjects were unable to complete the experiment due to severe nausea. When we divide our subject population into two categories: "non-sick" when the physical well-being ratings were below 2 (19 subjects), and "sick" for ratings of 2 or higher (11 subjects), we find a statistical significant effect of sickness on appraisal (p<0.003). A post hoc test contributes this to the arousing-sleepy dimension (p<0.05) and the pleasant-unpleasant dimension (p<0.06): sick subjects typically rate more sleepiness and unpleasantness than non-sick subjects. We conclude that cybersickness may be a confounding factor in the affective appraisal of VEs.

In the development of 3D models of buildings, much time and effort is spent on enhancing lighting effects, to improve the perceived realism and quality of the models, and to create ambience. In an experimental setup, two versions of a 3D model of the Royal Carré Theater with different lighting conditions were presented to viewers, to assess the influence of lighting effects on their affective appraisals. A small group visited the real theater. The differences between the affective qualities of the models are smaller than expected, and participants seem to infer affective qualities and dimensions of an environment without paying attention to the specific lighting information. The affective qualities of the real theater show a correspondence to both versions.

We investigated whether manipulation of visual and auditory depth and speed cues can affect a user's sense of risk for a low-cost nonimmersive virtual environment (VE) representing a highway environment with traffic incidents. The VE is currently used in an examination program to assess procedural knowledge of highway patrol officers. In its original form, the VE did not convey the danger of the simulated incidents, and trainees did not experience a sense of risk, even though important elements which contribute to a sense of danger in reality (like the speed and proximity of vehicles) were accurately modeled. This deficiency seriously degrades the validity of the VE as an examination tool. To provide viewers a more compelling impression of a simulated highway incident, we added variability to traffic behavior, and enhanced and added several visual and auditory depth and speed cues in the VE, which are known to affect risk perception in reality. Participants passively watched video clips of both the original and the enhanced versions of the simulation, and actively performed a lane crossing task in both interactive versions of the VE. Then, they filled out questionnaires addressing their speed, distance, and risk perception. The implemented changes did not affect speed and distance estimates, but significantly increased perceived personal risk. These results show that relatively minor changes to the visual, auditory, and dynamic aspects of a VE, established through proper analysis of user requirements and tasks, can significantly influence a user's experience, and thus determine the validity of the simulation for training and evaluation applications.

SoilGolf is a mixed reality game for educational purposes. The design integrates the subject matter (soils as a resource for life) with features of a virtual golf course into an engaging outdoor activity in the real world using geo coordinates. We tested the design of the game with two techniques and evaluated their usefulness for the development of games. Some technical difficulties in implementation are discussed.