Researchers have proposed that immersion could have advantages for tasks involving abstract mental activities, such as conceptual learning; however, there are few empirical results that support this idea. We hypothesized that higher levels of immersion would benefit such tasks if the mental activity could be mapped to objects or locations in a 3D environment. To investigate this hypothesis, we performed an experiment in which participants memorized procedures in a virtual environment and then attempted to recall those procedures. We aimed to understand the effects of three components of immersion on performance. The results demonstrate that a matched software field of view (SFOV), a higher physical field of view (FOV), and a higher field of regard (FOR) all contributed to more effective memorization. The best performance was achieved with a matched SFOV and either a high FOV or a high FOR, or both. In addition, our experiment demonstrated that memorization in a virtual environment could be transferred to the real world. The results suggest that, for procedure memorization tasks, increasing the level of immersion even to moderate levels, such as those found in head mounted displays (HMDs) and display walls, can improve performance significantly compared to lower levels of immersion. Hypothesizing that the performance improvements provided by higher levels of immersion can be attributed to enhanced spatial cues, we discuss the values and limitations of supplementing conceptual information with spatial information in educational VR.

Few production virtual environment (VE) applications involve complex three-dimensional (3D) interaction. Our long-term collaboration with architects and engineers in designing 3D user interfaces (3D UIs) has revealed some of the causes: existing interaction tasks and/or techniques are either too generic when isolated from the application context, or too specific to be reusable. We propose a new design approach called domain-specific design (DSD) that sits between the generic and specific design approaches, with an emphasis on using domain knowledge in 3D interaction techniques. We also describe an interaction design framework encompassing generic, domain-specific, and application-specific interaction tasks and techniques. This framework can be used by designers to think of ways to produce domain-specific interaction techniques. We present a particular DSD method, and demonstrate its use for the design of cloning techniques in a structural engineering application. Results from empirical studies demonstrate that interaction techniques produced with domain knowledge in mind outperformed other techniques by improving task efficiency, work flow, and usefulness of the 3D UI.

Virtual environments (VEs) are a relatively new type of human–computer interface in which users perceive and act in a three-dimensional world. The designers of such systems cannot rely solely on design guidelines for traditional two-dimensional interfaces, so usability evaluation is crucial for VEs. This paper presents an overview of VE usability evaluation to organize and critically analyze diverse work from this field. First, we discuss some of the issues that differentiate VE usability evaluation from evaluation of traditional user interfaces such as GUIs. We also present a review of some VE evaluation methods currently in use, and discuss a simple classification space for VE usability evaluation methods. This classification space provides a structured means for comparing evaluation methods according to three key characteristics: involvement of representative users, context of evaluation, and types of results produced. Finally, to illustrate these concepts, we compare two existing evaluation approaches: testbed evaluation (Bowman, Johnson, & Hodges, 1999) and sequential evaluation (Gabbard, Hix, & Swan, 1999).

As immersive virtual environment (VE) applications become more complex, it is clear that we need a firm understanding of the principles of VE interaction. In particular, designers need guidance in choosing three-dimensional interaction techniques. In this paper, we present a systematic approach, testbed evaluation, for the assessment of interaction techniques for VEs. Testbed evaluation uses formal frameworks and formal experiments with multiple independent and dependent variables to obtain a wide range of performance data for VE interaction techniques. We present two testbed experiments, covering techniques for the common VE tasks of travel and object selection/manipulation. The results of these experiments allow us to form general guidelines for VE interaction and to provide an empirical basis for choosing interaction techniques in VE applications. Evaluation of a real-world VE system based on the testbed results indicates that this approach can produce substantial improvements in usability.

Three-dimensional user interface design is a critical component of any virtual environment (VE) application. In this paper, we present a broad overview of 3-D interaction and user interfaces. We discuss the effect of common VE hardware devices on user interaction, as well as interaction techniques for generic 3-D tasks and the use of traditional 2-D interaction styles in 3-D environments. We divide most user-interaction tasks into three categories: navigation, selection/manipulation, and system control. Throughout the paper, our focus is on presenting not only the available techniques but also practical guidelines for 3-D interaction design and widely held myths. Finally, we briefly discuss two approaches to 3-D interaction design and some example applications with complex 3-D interaction requirements. We also present an annotated online bibliography as a reference companion to this article.

As virtual environment (VE) technology becomes accessible to (and affordable for) an ever-widening audience of users, the demand for VE applications will increase. Tools that assist and facilitate the development of these applications, therefore, will also be in demand. To support our efforts in quickly designing and implementing VE applications, we have developed the Simple Virtual Environment (SVE) library. In this article, we describe the characteristics of the library that support the development of both simple and complex VE applications. Simple applications are created by novice programmers or for rapid prototyping. More-complex applications incorporate new user input and output devices, as well as new techniques for user interaction, rendering, or animation. The SVE library provides more-comprehensive support for developing new VE applications and better supports the various device configurations of VE applications than current systems for 3-D graphical applications. The development of simple VE applications is supported through provided default interaction, rendering, and user input and output device handling. The library's framework includes an execution framework that provides structure for incrementally adding complexity to selected tasks of an application, and an environment model that provides a layer of abstraction between the application and the device configuration actually used at runtime. This design supports rapid development of VE applications through incremental development, code reuse, and independence from hardware resources during the development.

An experiment is presented comparing the effects of various virtual travel techniques in an immersive virtual environment (VE) on the spatial orientation of users. The experiment was designed and implemented in the context of a formal framework for the design and evaluation of VE travel techniques. Subjects traveled through virtual corridors, noting the location of objects along the way, and were asked to point in the direction of one of these objects when the end of the corridor was reached. Results indicate that virtual travel techniques, in which users do not physically translate their bodies, can allow the maintenance of a user's spatial orientation as measured by a pointing task. The experiment also replicates an earlier result, showing that path dimension significantly affects user performance. Finally, the strategies used by subjects to perform the task were shown to be significant, indicating that performance depends not only on the technique, environment, and task, but also on the sophistication of the user.

Information-rich virtual environments consist not only of three-dimensional graphics and other spatial data but also information of an abstract or symbolic nature that is related to the space. An environment of this type can stimulate learning and comprehension, because it provides a tight coupling between symbolic and experiential information. In our virtual zoo exhibit, students can explore an accurate model of the gorilla habitat at Zoo Atlanta and access information related to the design of the exhibit. This paper discusses the design of the application and the interaction techniques used to obtain information. We also present the results of a formal evaluation. Although no statistically significant differences were found, results indicate that students who used the virtual environment had higher test scores than those who only attended a lecture on the material. Trends suggest that the virtual experience allowed students to learn information directly and also equipped them to better learn and understand material from a traditional lecture.

We present a virtual environment application that allows users to access embedded information within an immersive virtual space. Due to the richness and complexity of this environment, efficient and easy-to-use interaction techniques are a crucial requirement. The “Virtual Venue” seamlessly combines both twoand three-dimensional interaction techniques into a single system and utilizes previously reported as well as novel techniques that fit the task of information access. We present tools for user control of the system, travel through the environment, and information retrieval, as well as authoring tools for the creation of information-rich virtual environments. A usability study and its results are also presented and discussed. The study indicates that the use of abstract information that is tightly coupled to the virtual environment can be quite successful in enhancing the relevance of both the environment and the information. Results also show that the set of well-constrained interaction techniques presented here are usable and efficient for information retrieval.