From: Doug Bowman [bowman@cs.vt.edu] Sent: Thursday, November 04, 1999 11:12 AM To: 3dui List Subject: exo- vs. ego-centric tasks Greetings all: As you may remember from previous postings, I'm thinking about doing some comparative studies of different VE display types. One of the differences that seems pretty intuitively clear is the distinction between an egocentric, 1st person, point of view (HMDs, CAVE), and an exocentric, 3rd person, point of view (Workbench). Of course, you can do an exocentric view in an HMD and an egocentric view on the workbench, but that seems to go against the "natural" use of these displays. So, I'd like to test both types of tasks using both types of displays, and try to show that HMDs and CAVEs excel when the user is doing an egocentric task from an egocentric point of view, and that workbenches excel when a user is doing an exocentric task from an exocentric point of view. The problem is finding *tasks* that are by nature exo- or egocentric. In fact, for almost every task I can think of ways to accomplish it from a first- or third-person point of view. Take driving: it seems clearly egocentric, but some people can develop highly accurate driving skills for the task of steering a vehicle while looking down on it from above (remember the old video game "Tank"?). The same is true of a task like surgery, which seems exocentric, but you could argue that certain delicate procedures could be done even better if I could see through the "eyes" of the instrument instead of my own. Rudy Darken talked about this in his VR '99 paper with relation to the usage of maps in virtual environments. He claimed that targeted search (the target is shown on the map) is best performed from an egocentric reference frame and primed or naive searches are best performed from a world reference frame. However, this is a bit different from doing these tasks from an ego- or exocentric *point of view*. So, two questions: 1. Are tasks inherently exocentric or egocentric? 2. If so, what are some examples of each? My current list for #2, which I'm not satisfied with: exocentric: puzzle assembly, global spatial relationships, surgery,... egocentric: line of sight tasks, driving, local spatial relationships... Looking forward to your comments. -- Doug A. Bowman, Ph.D. (540) 231-7537 Assistant Professor bowman@vt.edu Computer Science www.cs.vt.edu/~bowman/ Virginia Tech