Organizational Unit:

GVU Center

Permanent Link

https://hdl.handle.net/1853/70651

Includes Organization(s)

Organizational Unit

Interactive Media Technology Center

ArchiveSpace Name Record

https://finding-aids.library.gatech.edu/agents/corporate_entities/1093

Full item page

Publication Search Results

Now showing 1 - 10 of 50

Efficient Ray Intersection for Visualization and Navigation of Global Terrain using Spheroidal Height-Augmented Quadtrees

(Georgia Institute of Technology, 1999) Wartell, Zachary Justin ; Ribarsky, William ; Hodges, Larry F.

We present an algorithm for efficiently computing ray intersections with multi-resolution global terrain partitioned by spheroidal height-augmented quadtrees. While previous methods support terrain defined on a Cartesian coordinate system, our methods support terrain defined on a two-parameter ellipsoidal coordinate system. This curvilinear system is necessary for an accurate model of global terrain. Supporting multi-resolution terrain and quadtrees on this curvilinear coordinate system raises a surprising number of complications. We describe the complexities and present solutions. The final algorithm is suited for interactive terrain selection, collision detection and simple LOS (line-of-site) queries on global terrain.
Balancing Fusion, Image Depth and Distortion in Stereoscopic Head-Tracked Displays

(Georgia Institute of Technology, 1999) Wartell, Zachary Justin ; Ribarsky, William ; Hodges, Larry F.

Stereoscopic display is a fundamental part of virtual reality HMD systems and HTD (head-tracked display) systems such as the virtual workbench and the CAVE. A common practice in stereoscopic systems is deliberate incorrect modeling of user eye separation. Underestimating eye separation is frequently necessary for the human visual system to fuse stereo image pairs into single 3D images, while overestimating eye separation enhances image depth. Unfortunately, false eye separation modeling also distorts the perceived 3D image in undesirable ways. This paper makes three fundamental contributions to understanding and controlling this stereo distortion. (1) We analyze the distortion using a new analytic description. This analysis shows that even with perfect head tracking, a user will perceive virtual objects to warp and shift as she moves her head. (2) We present a new technique for counteracting the shearing component of the distortion. (3) We present improved methods for managing image fusion problems for distant objects and for enhancing the depth of flat scenes.
The Perceptive Workbench: Towards Spontaneous and Natural Interaction in Semi-Immersive Virtual Environments

(Georgia Institute of Technology, 1999) Leibe, Bastian ; Starner, Thad ; Ribarsky, William ; Wartell, Zachary Justin ; Krum, David Michael ; Singletary, Bradley Allen ; Hodges, Larry F.

The Perceptive Workbench enables a spontaneous, natural, and unimpeded interface between the physical and virtual world. It is built on vision-based methods for interaction that remove the need for wired input devices and wired tracking. Objects are recognized and tracked when placed on the display surface. Through the use of multiple light sources, the objectUs 3D shape can be captured and inserted into the virtual interface. This ability permits spontaneity as either preloaded objects or those selected on the spot by the user can become physical icons. Integrated into the same vision- based interface is the ability to identify 3D hand position, pointing direction, and sweeping arm gestures. Such gestures can support selection, manipulation, and navigation tasks. In this paper the Perceptive Workbench is used for augmented reality gaming and terrain navigation applications, which demonstrate the utility and capability of the interface.
Can Audio Enhance Visual Perception and Performance in a Virtual Environment?

(Georgia Institute of Technology, 1999) Davis, Elizabeth T. ; Scott, Kevin ; Pair, Jarrell ; Hodges, Larry F. ; Oliverio, James

Does the addition of audio enhance visual perception and performance within a virtual environment? To address this issue we used both a questionnaire and an experimental test of the effect of audio on recall and recognition of visual objects within different rooms of a virtual environment. We tested 60 college-aged students who had normal visual acuity, color vision, and hearing. The between-participants factor was audio condition (none, low fidelity, and high fidelity). The questionnaire results showed that ambient sounds enhanced the sense of presence (or "being there") and the subjective 3D quality of the visual display, but not the subjective dynamic interaction with the display. We also showed that audio can enhance recall and recognition of visual objects and their spatial locations within the virtual environment. These results have implications for the design and use of virtual environments, where audio sometimes can be used to compensate for the quality of the visual display.
The Analytic Distortion Induced by False-Eye Separation in Head-Tracked Stereoscopic Displays

(Georgia Institute of Technology, 1999) Wartell, Zachary Justin ; Hodges, Larry F. ; Ribarsky, William

Stereoscopic display is a fundamental part of virtual reality systems such as the virtual workbench, the CAVE and HMD systems. A common practice in stereoscopic systems is deliberate incorrect modeling of user eye separation. Under estimating eye separation can help the human visual system fuse stereo image pairs into single 3D images, while over estimating eye separation enhances image depth. Unfortunately, false eye separation modeling also distorts the perceived 3D image in undesirable ways. We present a novel analytic expression and quantitative analysis of this distortion for eyes at an arbitrary location and orientation.
Toolsets for the Development of Highly Interactive and Information-Rich Virtual Environments

(Georgia Institute of Technology, 1998) Bowman, Douglas A. ; Hodges, Larry F.

This paper describes a unique set of programming toolsets which are designed specifically to aid in the authoring of immersive virtual environment (VE) applications. The first toolset provides a wide range of user interface options through a pen-based metaphor, and benefits applications which have a high degree of interactive complexity. The second toolset allows high-level control of audio annotations, and benefits applications which provide information to the user via the audio modality. The toolsets are designed to provide abstraction from the basic VE software system, to allow rapid prototyping and experimentation, and to be reusable across multiple applications. Two applications which have made extensive use of both toolsets are also presented.
A Methodology for the Evaluation of Travel Techniques for Immersive Virtual Environments

(Georgia Institute of Technology, 1998) Bowman, Douglas A. ; Koller, David ; Hodges, Larry F.

We present a framework for the analysis and evaluation of travel, or viewpoint motion control, techniques for use in immersive virtual environments (VEs). The basic construct of this framework is a taxonomy of travel techniques, and we present a summary of three experiments mapping parts of the taxonomy to various performance measures. Since these initial experiments, we have expanded the framework to allow evaluation of not only the effects of different travel techniques, but also the effects of many outside factors simultaneously. Combining this expanded framework with the measurement of multiple response variables epitomizes the philosophy of testbed evaluation. This experimental philosophy leads to a deeper understanding of the interaction and the technique(s) in question, as well as to broadly generalizable results. We also present an example experiment within this expanded framework, which evaluates the user's ability to gather information while traveling through a virtual environment. Results indicate that, of the variables tested, the complexity of the environment is by far the most important factor.
The Simple Virtual Environment Library: Verson 2.0 Users Guide

(Georgia Institute of Technology, 1998) Kessler, Gregory Drew ; Kooper, Rob ; Hodges, Larry F.

The Simple Virtual Environments (SVE) C library provides a framework for the development of virtual environment (VE) applications. The library provides the default components of simple VE applications (such as fly-throughs), allowing these applications to be quickly implemented, and allows applications to selectively alter, enhance, or replace components such as user interactions, animations, rendering, and input device polling. The library also allows the hardware and software configuration (devices used and placement in the workspace, location of remote servers, directories, etc.) to be given at run-time using an initialization file. Therefore, SVE provides support for rapid prototyping as well as complete implementation of simple and complex VE applications.
Third-Person Navigation of Whole-Planet Terrain in a Head-tracked Stereoscopic Environment

(Georgia Institute of Technology, 1998) Wartell, Zachary Justin ; Ribarsky, William ; Hodges, Larry F.

Navigation and interaction in stereoscopic virtual environments with head-tracking for very large data sets present several challenges beyond those encountered with smaller or monoscopic data sets. First, zooming by approaching or retreating from a target must be augmented by integrating scale as a seventh degree of freedom. Second, in order to maintain good stereoscopic imagery, the interface must: maintain stereo image pairs that the user perceives as a single 3D image, minimize loss of perceived depth since stereoscopic imagery cannot properly occlude the screen's frame, provide maximum depth information, and place objects at distances where they are best manipulated. Finally, the navigation interface must work when the environment is displayed at any scale. This paper addresses these problems for god's-eye-view or third person navigation of a specific large-scale virtual environment: a high-resolution terrain database covering an entire planet.
Interaction in Semi-Immersive Large Display Environments

(Georgia Institute of Technology, 1998) Van de Pol, Rogier ; Ribarsky, William ; Hodges, Larry F. ; Post, F. H. (Frits H.)

This paper evaluates interaction methods within the general framework of navigation, selection, and manipulation. It considers large display environments and, in particular, the virtual workbench, comparing this system with HMD and CAVE systems. The paper addresses three issues: (a) identifying the characteristics that set the workbench apart from other virtual environments; (b) determining types, organization, and examples of interaction techniques: (c) evaluating how these techniques perform on the workbench to determine which perform best. The evaluations are based on an extensive set of user observations. Also discussed are some problems that stereoscopic display coupled with interaction bring out.