Navigation in desktop virtual environments: an evaluation and recommendations for supporting usability

Virtual reality (VR) can provide useful tools for a variety of applications. However, for these tools to be effective, they must be easy to use. In virtual environments (VEs), usability is impaired by poorly designed navigation systems. Insufficient realism and missing physiological orientation and motion cues impair spatial learning in desktop VEs. Capabilities for navigation in a VE are far more varied than in reality; so much greater flexibility can be offered, but designing VEs with too many options can overwhelm users. To assist designers in building effective, usable navigation systems for VEs, navigation techniques must be evaluated to identify which features actually support users in accomplishing their tasks and which features create unnecessary problems.This study evaluates navigation in two different VEs to develop recommendations for the design of navigation systems in desktop VEs. The study consists of an objective assessment of navigation control dynamics, a guideline-based evaluation and a review of data collected during two experimental studies. The findings indicate that real-world constraints, specialised navigation techniques and feedback regarding location and direction of travel are needed to support navigation in desktop VEs.     

The frequent wayfinding-sequence (FWS) methodology: Finding preferred routes in complex virtual environments

Advances in computing techniques, as well as the reduction in the cost of technology, have made possible the viability and spread of complex virtual environments (VEs). However, efficient navigation within these environments remains problematic for the user. Several research projects have shown that users of VEs are often disoriented and have extreme difficulty completing navigational tasks. Furthermore, there is often more than one route to get to a specified destination. Novice users often lack the spatial knowledge needed to pick an appropriate route due to the deficiency of experience with the system. A number of navigation tools such as maps, 3-D thumbnails, trails, and personal agents have been proposed. The introduction of these tools have met with some degree of success, but most researchers agree that new techniques need to be developed to aid users efficiently navigate within complex VEs. In this paper, we propose the frequent wayfinding-sequence (FWS) methodology that uses a modified sequence mining technique to discover a model of routes taken by experienced users of a VE. The model is used to build an interface that provides navigation assistance to novice users by recommending routes. We conducted both real world and simulation experiments using our methodology. Results from the real world experiment suggest that the FWS approach has the potential to improve the user's navigation performance and the quality of the human-computer interaction. Our simulation studies showed that our approach is scalable, efficient, and able to find useful route models for complex VEs.     

A comparison of guidance cues in desktop virtual environments

Designers of educational and entertainment desktop virtual environments (VEs) have employed a variety of cues for motivating users to perform actions or adopt particular viewpoints. However, there has been little formal study comparing user responses to such cues. This paper reports the results of a preliminary study of five cues (agents, signs, man-made landmarks, environmental landmarks, and trails) for motivating actions in virtual environments. Given a sample task of navigating to a target destination, no significant differences between the cues were observed in terms of overall success or speed. However, significant differences between the cues were found on other measures, including minimization of detours (trails) and awareness of guidance (agents, signs, trails). Frequency of desktop VE usage was also found to influence performance.     

VU-flow: a visualization tool for analyzing navigation in virtual environments

This paper presents a tool for the visual analysis of navigation patterns of moving entities, such as users, virtual characters or vehicles in 3D virtual environments (VEs). The tool, called VU-Flow, provides a set of interactive visualizations that highlight interesting navigation behaviors of single or groups of moving entities that were the VE together or separately. The visualizations help to improve the design of VEs and to study the navigation behavior of users, e.g., during controlled experiments. Besides VEs, the proposed techniques could also be applied to visualize real-world data recorded by positioning systems, allowing one to employ VU-Flow in domains such as urban planning, transportation, and emergency response     

Evaluating design guidelines for reducing user disorientation in a desktop virtual environment

Navigation in virtual environments can be difficult. One contributing factor is user disorientation. Two major causes of this are the lack of navigation cues in the environment and problems with navigating too close to or through virtual world objects. Previous work has developed guidelines, informed by cinematography conventions, for the construction of virtual environments to aid user comprehension of virtual space to reduce user disorientation. To validate these guidelines, two user studies have been performed where users of a desktop virtual environment are to complete a navigation task in a virtual maze. In an initial study [12], collision detection with the maze walls was not enabled and the results indicated that the guidelines were effective for reducing disorientation but not for developing the users awareness of the environment space. A second study has been performed where collision detection was enabled. Results suggest that the use of the guidelines can help reduce the incidences of user disorientation and aid navigation tasks. However, the guidelines have little impact on users ability to construct cognitive maps of the desktop virtual environment.

Evaluation of Reorientation Techniques and Distractors for Walking in Large Virtual Environments

Vir tual Environments (VEs) that use a real-walking locomotion interface have typically been restricted in size to the area of the tracked lab space. Techniques proposed to lift this size constraint, enabling real walking in VEs that are larger than the tracked lab space, all require reorientation techniques (ROTs) in the worst-case situation—when a user is close to walking out of the tracked space. We propose a new ROT using visual and audial distractors—objects in the VE that the user focuses on while the VE rotates—and compare our method to current ROTs through three user studies. ROTs using distractors were preferred and ranked more natural by users. Our findings also suggest that improving visual realism and adding sound increased a user's feeling of presence. Users were also less aware of the rotating VE when ROTs with distractors were used.     

Dynamic Maps for Exploring and Browsing Shapes

Large datasets of 3D objects require an intuitive way to browse and quickly explore shapes from the collection. We present a dynamic map of shapes where similar shapes are placed next to each other. Similarity between 3D models exists in a high dimensional space which cannot be accurately expressed in a two dimensional map. We solve this discrepancy by providing a local map with pan capabilities and a user interface that resembles an online experience of navigating through geographical maps. As the user navigates through the map, new shapes appear which correspond to the specific navigation tendencies and interests of the user, while maintaining a continuous browsing experience. In contrast with state of the art methods which typically reduce the search space by selecting constraints or employing relevance feedback, our method enables exploration of large sets without constraining the search space, allowing the user greater creativity and serendipity. A user study evaluation showed a strong preference of users for our method over a standard relevance feedback method.     

Identification of metaphors for virtual environment training systems

The objective of this effort was to develop potential metaphors for assisting wayfinding and navigation in current virtual environment (VE) training systems. Although VE purports a number of advantages over traditional, full-scale simulator training devices (deployability, footprint, cost, maintainability, scalability, networking), little design guidance exists beyond individual instantiations with specific platforms. A review of metaphors commonly incorporated into human—computer interactive systems indicated that existing metaphors have largely been used as orientation aids, mainly in the form of guided navigational assistance, with some position guidance. Advanced metaphor design concepts were identified that would not only provide trainees with a useful orienting framework but also enhance visual access and help differentiate an environment. The effectiveness of these concepts to aid navigation and wayfinding in VEs must be empirically validated.     

Wayfinding of Users With Visual Impairments in Haptically Enhanced Virtual Environments

As a powerful interaction technology, haptically enhanced virtual environments (VEs) have found many useful applications. However, few studies have examined how wayfinding of users with visual impairments is affected by VE characteristics. An empirical experiment was conducted to investigate how different environmental characteristics (number of objects inside the environment, layout of the objects and density) affect task performance (completion time, completion ratio, and travel distance), perceived task difficulty, and behavior pattern (short and long pause) of users with visual impairments when they perform a wayfinding task in a desktop-based haptically enhanced VE. The present study found that the number of objects inside the environment and layout of the objects play a significant role in determining the completion time and distance traveled. Layout type also greatly affected the user’s behavioral pattern in terms of frequency of pauses. Finally, perceived task difficulty varied with different environmental characteristics. The study results should provide insight into the future research and development of haptically enhanced VEs for people with visual impairments.     

Identification of metaphors for virtual environment training systems

The objective of this effort was to develop potential metaphors for assisting wayfinding and navigation in current virtual environment (VE) training systems. Although VE purports a number of advantages over traditional, full-scale simulator training devices (deployability, footprint, cost, maintainability, scalability, networking), little design guidance exists beyond individual instantiations with specific platforms. A review of metaphors commonly incorporated into human-computer interactive systems indicated that existing metaphors have largely been used as orientation aids, mainly in the form of guided navigational assistance, with some position guidance. Advanced metaphor design concepts were identified that would not only provide trainees with a useful orienting framework but also enhance visual access and help differentiate an environment. The effectiveness of these concepts to aid navigation and wayfinding in VEs must be empirically validated.     

Navigation help in 3D worlds: some empirical evidences on use of sound

The concept of Interaction Locus (IL) has been introduced to help the users to orient, navigate, and identify relevant interaction areas in 3D Virtual Environments (VEs). The IL is a multimodal concept: it adds to the 3D visual scene parallel information channels that are perceived by other senses. In particular, the IL emphasizes the role of music as a navigation aid in a VE. This paper reports three user-evaluations of different IL enriched virtual worlds, and in particular of the role of the IL auditory component. Results suggest that audio in 3D plays not only an aesthetic role, which the users greatly appreciate, but also a functional role simplifying navigation and helping the users to recognise scenes in the environment. Such a functional role however is subordinated to a proper understanding of the link between music and virtual space. While these experiments refer to desktop virtual reality environments, their findings are general enough to inform the design of navigational tools for other segments of the mixed reality domain.

Adapting the Navigation Interface of Smart Watches to User Movements

ABSTRACT

The high mobility of smart watches can easily impair interaction performance, and many applications are squeezed into an extremely tiny screen, which causes disorientations. Therefore, this study examines the extent of performance impairment caused by user movements and proposes navigation aids to alleviate the impairment. An experiment was conducted among 28 college students to investigate the influence of user movements and navigation aids on users’ performance and subjective feedback. The results indicate that the performance of using smart watches in walking conditions is comparable to that in sitting conditions. However, the use of smart watches while running reduces the success rates of operating, perceived ease of use, perceived usefulness, and flow experience, and it increases subjective cognitive workload. To improve user experience, the effectiveness of providing navigation aids for smart watches is confirmed. Using static navigation aids while sitting and walking and using animated navigation aids while moving can significantly improve users’ perceived ease of use and perceived usefulness and decrease cognitive workload. Based on these results, guidelines for tailoring the interface design of smart watches to user movements through navigation aids are proposed.     

How to Overcome Disorientation in Mobile Phone Menus: A Comparison of Two Different Types of Navigation Aids

The current study was concerned with the basic question of how to overcome users' disorientation when navigating through hierarchical menus in small-screen technical devices, as for example mobile phones. In these devices, menu functions are typically organized in a tree structure. Two different navigation aids were implemented into a computer simulation of a real mobile phone (Siemens S45®). The interface of the first navigation aid (the "category" aid) showed the name of the current category as well as a list of its contents. The interface of the other navigation aid (the "tree" aid) was identical to the first except that it also showed the parents and parent–parents of the current of the category and it indented the subcategories to emphasize the hierarchical structure. For the study, 16 younger (23–28 years) and 16 older adults (46–60 years) had to solve 9 common phone tasks twice consecutively to measure learnability. To gain further insight into user characteristics modulating navigation performance and possibly interacting with the utility of the navigation aids, we assessed users' verbal memory and spatial abilities. Dependent variables were task effectiveness (number of tasks solved) and efficiency (time on task, number of returns in menu hierarchy, and returns to the top). The results reveal a consistent and significant advantage of the tree aid for both age groups, an advantage that was larger for users with lower spatial abilities and older adults. In general, older adults had lower verbal memory and spatial abilities, which were found to account for their lower navigation performance. We assume that the strong advantage of the tree aid is due to the spatial information on the menu structure, which thus conveys survey knowledge. This allows users to form an adequate mental representation of the menu. It is recommended to add a navigation aid providing survey knowledge into the displays of small-screen devices to achieve better overall performance.     

The use of virtual environments based on a modification of the computer game Quake III Arena in psychological experimenting

We investigated whether newly developed virtual 3D environments (VEs) based on a modification of the computer game Quake III Arena^® are suitable for psychological experimenting. Internal validity of data collected in VEs may be threatened due to a priori individual differences in general performance in VE navigation and in susceptibility to cybersickness. The main question was whether individual differences in performance can be diminished by means of training. Additionally, the susceptibility of different subsamples to cybersickness when moving within VEs was examined. 85 participants took part in an experiment where they had to fulfill simple tasks in three VEs. Navigation performance was measured as the time participants needed to make their way through the VEs. Differences in navigation performance between different levels of experience were diminished by training, indicating that internal validity can be obtained. A classification tree reveals that game-inexperienced female participants aged over 31 years have the highest risk of experiencing cybersickness. VEs based on modifications of computer games seem to be an extremely promising and inexpensive possibility for the administration of psychological experiments.     

Navigational tools for desktop virtual environment interfaces

Desktop systems typically rely on a two-dimensional (2D) software interface and general purpose hardware (mouse, keyboard) for interaction with a three-dimensional (3D) virtual environment. These interfaces must provide all the functionality required to navigate through and interact with the virtual environment, yet research into the usability aspects of the tools presented on these software interfaces indicates that the majority of users experience some degree of frustration when using them to perform even relatively simple tasks. This paper begins with a study of usability issues for interfaces to virtual environments on desktop systems, and details a series of experiments performed to evaluate the usability of a number of navigational tools. Participants were tested on the time taken to complete a number of navigational tasks with a series of interfaces presenting different navigational tools. The tools presented were a speed control function, a you-are-here (YAH) map, a function enabling the user to mark and teleport to any location within the presented environment, and an undo function. Results indicate that the visual presentation of navigational aids improves navigation performance, in terms of the time taken to complete tasks, and also improves user satisfaction with the desktop system.     

Virtual prints: Augmenting virtual environments with interactive personal marks

This paper introduces the concept of Virtual Prints (ViPs) as an intuitive metaphor for supporting interaction and navigation, as well as a number of additional tasks in virtual environments (VEs). Three types of ViPs are described: Virtual Footprints, which are used for tracking user navigation (position, orientation and movement), Virtual Handprints, which are used for tracing user interaction with the VE, and Virtual Markers, which are ‘special’ marks (usually coupled with information) that can be created upon user request. In a VE, the ViPs concept is instantiated and supported through a software mechanism (the ViPs mechanism) that allows users to create, manage and interact with their personal ViPs, as well as other users’ ViPs.The paper presents the background and related work upon which the suggested concept builds, as well as the distinctive properties that differentiate ViPs from other related efforts. An account of how users can interact with ViPs is provided and related issues and challenges are discussed along with techniques and methods for addressing them. The paper also describes the process followed towards defining and experimenting with the concept of ViPs by means of iterative design and evaluation of an interactive prototype. This process involved exploratory studies, as well as several inspections and formal tests with both experts and potential end-users, in order to assess the usefulness of the concept and identify possible shortcomings, and also to evaluate and improve the usability of the proposed designs and software prototypes. In general, the findings of the studies reinforce the initial hypothesis that ViPs are an intuitive and powerful concept, and show that the related software is easy to learn and use. Overall, the results of the studies support strong evidence that an appropriately designed and implemented, fully functional ViPs mechanism can significantly increase the usability of VEs.     

Interaction with an immersive virtual environment corrects users' distance estimates

OBJECTIVE: Two experiments examined whether prior interaction within an immersive virtual environment (VE) enabled people to improve the accuracy of their distance judgments and whether an improved ability to estimate distance generalized to other means of estimating distances. BACKGROUND: Prior literature has consistently found that users of immersive VEs underestimate distances by approximately 50%. METHOD: In each of the two experiments, 16 participants viewed objects in an immersive VE and estimated their distance to them by means of blindfolded walking tasks before and after interacting with the VE. RESULTS: The interaction task significantly corrected users' underestimation bias to nearly veridical. Differences between pre- and post-interaction mean distance estimation accuracy were large (d = 4.63), and significant (p < .001), and they generalized across response task. CONCLUSION: This finding limits the generality of the underestimation effect in VEs and suggests that distance underestimation in VEs may not be a road block to the development of VE applications. APPLICATION: Potential or actual applications of this research include the improvement of VE systems requiring accurate spatial awareness.     

Mobility impaired users respond differently than healthy users in virtual environments

Virtual environments (VEs) have been shown to be beneficial in physical rehabilitation, increasing motivation and the range of exercises that can be safely performed. However, little is known about how disabilities may impact a user's responses to a VE, which could affect rehabilitation motivation. Thus, the primary objective of this research is to understand how VEs affect users with mobility impairments (MI). Specifically, we investigate the influence of full body avatars that have canes. To begin investigating this, we designed a VE that included a range of multimodal feedback to induce a strong sense of presence and was novel to the participants. Using this VE, we conducted a study with two different populations: eight persons with MI and eight healthy persons as a control. The healthy participants were of similar demographics (e.g., age, weight, height, and previous VE experience) to the participants with MI who walked with a cane (i.e., on the basis of strict selection criteria to maintain homogeneity). This is one of the first studies to investigate how a VE can affect the gait of the users with MI, physiological response, presence, behavior, and the influence of avatars. Results of the study suggest generalizable guidelines for the design of VEs for users with MI. Copyright © 2014 John Wiley & Sons, Ltd.     

Contextual Navigation Aids for Two World Wide Web Systems

In spite of the radical enhancement of Web technologies, many users still continue to experience severe difficulties in navigating Web systems. One way to reduce the navigation difficulties is to provide context information that explains the current situation of Web users. In this study, we empirically examined the effects of 2 types of context information, structural and temporal context. In the experiment, we evaluated the effectiveness of the contextual navigation aids in 2 different types of Web systems, an electronic commerce system that has a well-defined structure and a content dissemination system that has an ill-defined structure. In our experiment, participants answered a set of postquestionnaires after performing several searching and browsing tasks. The results of the experiment reveal that the 2 types of contextual navigation aids significantly improved the performance of the given tasks regardless of different Web systems and different task types. Moreover, context information changed the users' navigation patterns and increased their subjective convenience of navigation. This study concludes with implications for understanding the users' searching and browsing patterns and for developing effective navigation systems.     

Geometric calibration of head-mounted displays and its effects on distance estimation

Head-mounted displays (HMDs) allow users to observe virtual environments (VEs) from an egocentric perspective. However, several experiments have provided evidence that egocentric distances are perceived as compressed in VEs relative to the real world. Recent experiments suggest that the virtual view frustum set for rendering the VE has an essential impact on the user's estimation of distances. In this article we analyze if distance estimation can be improved by calibrating the view frustum for a given HMD and user. Unfortunately, in an immersive virtual reality (VR) environment, a full per user calibration is not trivial and manual per user adjustment often leads to mini- or magnification of the scene. Therefore, we propose a novel per user calibration approach with optical see-through displays commonly used in augmented reality (AR). This calibration takes advantage of a geometric scheme based on 2D point - 3D line correspondences, which can be used intuitively by inexperienced users and requires less than a minute to complete. The required user interaction is based on taking aim at a distant target marker with a close marker, which ensures non-planar measurements covering a large area of the interaction space while also reducing the number of required measurements to five. We found the tendency that a calibrated view frustum reduced the average distance underestimation of users in an immersive VR environment, but even the correctly calibrated view frustum could not entirely compensate for the distance underestimation effects.