Betsy Williams

Updating orientation in large virtual environments using scaled translational gain

Navigating through large virtual environments using a head-mounted display (HMD) is difficult due to the spatial limitations of the tracking system. We conducted two experiments to examine methods of exploring large virtual spaces with an HMD under translation conditions different than normal walking. Experiment 1 compares locomotion in the virtual environment using two different motor actions to translate the subject. The study contrasts user learning and orientation of two different translational gains of bipedal locomotion (not scaled and scaled by ten) with joystick locomotion, where rotation in both locomotion interfaces is accomplished by physically turning. Experiment 2 looks further at the effects of increasing the translational gain of bipedal locomotion in a virtual environment. A subjects spatial learning and orientation were evaluated in three gain conditions where each physical step was: not scaled, scaled by two, or scaled by ten (1:1, 2:1, 10:1, respectively). A sub-study of this experiment compared the performance of people who played video games against people who did not.

Evaluation of walking in place on a Wii balance board to explore a virtual environment

In this work, we present a method of “Walking In Place” (WIP) on the Nintendo Wii Fit Balance Board to explore a virtual environment. We directly compare our method to joystick locomotion and normal walking. The joystick proves inferior to physically walking and to WIP on the Wii Balance Board (WIP--Wii). Interestingly, we find that physically exploring an environment on foot is equivalent in terms of spatial orientation to exploring an environment using our WIP--Wii method. This implies that the WIP--Wii is a good inexpensive alternative to exploring a virtual environment and it may be well--suited for exploring large virtual environments.

Do we need to walk for effective virtual reality navigation? physical rotations alone may suffice

Physical rotations and translations are the basic constituents of navigation behavior, yet there is mixed evidence about their relative importance for complex navigation in virtual reality (VR). In the present experiment, 24 participants wore head-mounted displays and performed navigational search tasks with rotations/translations controlled by physical motion or joystick. As expected, physical walking showed performance benefits over joystick navigation. Controlling translations via joystick and rotations via physical rotations led to better performance than joystick navigation, and yielded almost comparable performance to actual walking in terms of search efficiency and time. Walking resulted, however, in increased viewpoint changes and shorter navigation paths, suggesting a rotation/translation tradeoff and different navigation strategies. While previous studies have emphasized the importance of full physical motion via walking (Ruddle & Lessels, 2006, 2009), our data suggests that considerable navigation improvements can already be gained by allowing for full-body rotations, without the considerable cost, space, tracking, and safety requirements of free-space walking setups.

An algorithm for baseline correction of MALDI mass spectra

Visualization and differentiation of proteins in tissue are problems of increasing interest in computational systems biology, bioinformatics, and image processing. A platform for generating such proteomic information is matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). In imaging MALDI-MS, spatial information and protein expression can be created. However, data from imaging MALDI-MS spectra require considerable signal processing to generate quantitative results and to provide input to later classification algorithms. To compare MALDI-MS spectra at different spatial locations (sample-to-sample comparisons) or classify parts of the spectra, a processing step called baseline correction is essential. This paper reports a robust algorithm for computing the baseline correction of MALDI-MS spectra. The algorithm requires few user inputs and is suitable for automatically processing a large number of spectra, as is the case when generating images. The results of our algorithm are validated on a dataset of spectra available for comparison purposes.

Distance perception in virtual environments: a closer look at the horizon and the error

Distances are systematically underestimated in the virtual environments. In this work we explore the possibility of shifting the angular the angular declination from the horizon as a way of manipulating perceived distances in a head-mounted display (HMD). We find that shifting the horizon upward 11.5° upward does not have an effect on distance perception. Blind walking tasks at 1.5m, 2.5m, 3.5m, 4.5m and 5.5m show an overestimation of perceived distances less than 2.5m and an underestimation of perceived distances greater than 3.5m. Absolute distance and errors in estimating distance are linearly related.

Myo arm: swinging to explore a VE

In this paper, we use an inexpensive wearable device called the Myo armband (199 USD) to implement a simple arm swinging algorithm that allows a user to freely explore an HMD-based virtual environment. Using a spatial orientation task we directly compared our Myo arm--swinging method to joystick locomotion and physical walking. We find that our arm swinging method outperforms the simple joystick and that spatial orientation is comparable to physically walking on foot. Our arm--swinging method is inexpensive compared to tracking systems that permit foot exploration, does not suffer from space constraints, and requires less physical energy than walking on foot.

Examining the role of gestures in expert tutoring

It is well established that expert human tutors are significantly more effective than novice tutors [6]. Moreover, the dialogue moves of one–to–one expert tutoring sessions can be systematically analyzed and used to build a computational model that incorporates effective pedagogical strategies. Such a model can be successfully integrated into a computerized tutoring system [24]. The present work examines the role of gestures and body movements of tutors in one–to–one expert tutoring sessions. Specifically, we closely examine and characterize the gestures and movements of expert tutors at the dialogue move level. The goal of this work is to provide insight into the pedagogical gestures of expert human tutors so that a computerized animated agent can be employed to mimic the body language of an expert tutor.

Distance perception in virtual environments

Virtual environments provide people with the opportunity to experience places and situations remote from their actual physical surroundings. However, we cannot expect spatial representation in virtual environments to be as accurate as spatial representation in physical environments. One reason for this is that perceived distance is systematically underestimated in virtual environments. The precise reasons for this are unknown. This work uses the bisection method shown in Bodenheimer et al. [2007] to study the perceived distance in virtual environments. In the virtual environment, distance bisection involves subjects adjusting an avatar using a joystick until they feel that the avatar bisects the distance between themselves and a target avatar. Bodenheimer et al. [2007] examine errors resulting from judging the bisection at 15m and 30m. We examine errors resulting from judging the bisection from five different distances: 3m, 7.5m, 15m, 22.5m, and 30m. We observe a linear relationship between the amount of foreshortening in judging the midpoint and distance. Additionally, perceiving a virtual representation of ones self in the virtual environment makes subjects significantly more accurate at judging the midpoint at 3m. However, for distances greater than 7.5m we find that asking people to use their virtual representation to judge the bisection leads to a significant increase in the amount of foreshortening.

Virtual Exploration: Seated versus Standing.

Virtual environments are often explored standing up. The purpose of this work is to understand if standing exploration has an advantage over seated exploration. Thus, we present an experiment that directly compares subjects’ spatial awareness when locomoting with a joystick when they are physically standing up versus sitting down. In both conditions, virtual rotations matched the physical rotations of the subject and the joystick was only used for translations through the virtual environment. In the seated condition, users sat in an armless swivel office chair. Our results indicated that there was no difference between the two conditions, sitting and standing. However, this result is interesting and might compel more virtual environment developers to encourage their users to sit in a comfortable swivel chair. As an additional finding to our study, we find a significant difference between the performance of males versus females and gamers versus non–gamers.

The effect of interpersonal familiarity on cooperation in a virtual environment

Immersive virtual environments (VEs) allow people to experience situations which because of danger, expense, time, or distance would not otherwise be available. Moreover, IVEs have been shown to be useful tools for learning and training. However, there are still many unanswered questions about how humans experience and interact with these environments and how this experience differs from the real world. In the experiment presented in this work, we are specifically interested in how effectively two people will collaborate within an environment given that they have never met or even seen each other prior to the experiment. We postulate that participants who never meet their partner in a collaborative environment will perform worse than those who are able to interact with their partner prior to the performance of a task. If this holds true, then it could have important implications for long distance collaboration.