Evaluation of Virtual Travel Techniques

In this project, we hope to categorize and evaluate methods used for travel in three-dimensional, immersive virtual environments. Our focus is limited to virtual (not physical) motion with a first person point-of-view. We have created a taxonomy of techniques, based on three components which must be addressed in any virtual travel method:

Direction/Target Selection
Velocity/Acceleration Selection
Conditions of Travel (input required)

We have also created a partial list of quality factors which may be important to the designers of virtual travel techniques. These include:

Speed to target
Accuracy of reaching target
Amount of user disorientation
Amount of cognitive load required for use
Ability to gather information while travelling
Feeling of presence within the environment while travelling

Since most, if not all, of these quality factors are measurable, we have proposed a series of experiments to evaluate the utility of various techniques or components of techniques with respect to these factors. In particular, we do not propose to find the "best" technique overall, or even the best technique for a given application. Rather, we measure a technique's "score" for one or more of the quality factors, and allow application developers to decide the weight given to each factor.

So far, we have conducted four experiments within our evaluation framework:

1. Relative Motion Test

The user moves relative to the pointer in the left of the picture to the spot denoted by the sphere at right. The sphere is not visible during the trials.

We measure the usefulness of a technique for moving to a point in space relative to an object. In particular, we are testing gaze-directed direction selection vs. direction selection via pointing.

2. Disorientation due to velocity/acceleration

After travel, the user must find the cube whose color matches the stimulus in the upper left corner.

The goal is to obtain a measure of the amount of directional disorientation due to the velocity and/or acceleration of travel. Four techniques are used:

Constant, slow velocity
Constant, fast velocity
Slow-in, slow-out acceleration
Jumping (infinite velocity)

3. Speed to target characterization

By varying the distance to and the size of the target, we can simultaneously measure speed and accuracy, in a manner similar to Fitts' Law. We are examining two factors here: gaze vs. pointing and constrained vs. unconstrained motion.

4. Information Gathering characterization

The user's view inside the corridor.

An outside view of a 3-Dimensional corridor.

Subjects traveled through 1-, 2-, and 3-dimensional corridors, collecting information (words and locations) as they moved. We studied not only travel technique (gaze-directed, pointing, torso-directed), but also the use of collision detection, and the dimensionality of the travel path.

Project Participants:

Doug Bowman
David Koller

Publications:

Bowman, D., Koller, D., and Hodges, L., "A Methodology for the Evaluation of Travel Techniques for Immersive Virtual Environments," currently submitted to PRESENCE.
Download a PostScript Version of the paper

Bowman, D., Koller, D., and Hodges, L., "Travel in Immersive Virtual Environments: An Evaluation of Viewpoint Motion Control Techniques," in the Proceedings of the Virtual Reality Annual International Symposium (VRAIS), 1997.
View the Abstract
Download a PostScript Version of the paper

Contact Information:

Doug A. Bowman - Graduate Student

Georgia Institute of Technology

College of Computing

Atlanta GA 30332-0280

(404) 894-5104 (Phone)

By E-MAIL :

bowman@cc.gatech.edu