Table of Contents:

  1. Principal Investigator.
  2. Productivity Measures.
  3. Summary of Objectives and Approach.
  4. Detailed Summary of Technical Progress.
  5. Transitions and DOD Interactions.
  6. Software and Hardware Prototypes.
  7. List of Publications.
  8. Invited and Contributed Presentations.
  9. Honors, Prizes or Awards Received.
  10. Project Personnel Promotions.
  11. Project Staff.
  12. Multimedia URL.
  13. Keywords.
  14. Business Office.
  15. Expenditures.
  16. Students.
  17. Book Plans.
  18. Sabbatical Plans.
  19. Related Research.
  20. History.

Principal Investigator.

Productivity Measures.

Summary of Objectives and Approach.

  1. Virtual reality (VR) is emerging as an important approach to the modeling and simulation of complex systems. But software technology for scientists to build VR-based applications fosters development of closed applications each built from scratch. A scientist's ability to merge models and systems once developed is solely dependent upon their ability to `hack' software, since the principles of VR system interconnection are poorly understood and no software engineering guidelines have ever been developed for use in VR applications.
  2. We are studying the issue of interoperation between VR systems, that is the virtual environment, in order to discover essential principles governing their construction and effective use. Our approach focuses upon the control properties of interfaces between VR applications: existing VR applications will be examined in order to expose commonalities, and our abstractions of VR control behavior will be specified in terms of the software bus model of interconnection. As principles of VR interoperation emerge, we will build prototype implementations of corresponding software interconnection tools to evaluate the application of those principles back in the domains from which our test problems were drawn. As a result of this research, scientists who use VR technology will have a sound basis for leveraging existing resources in new applications, and similarly, they will have an appropriately abstract framework for specifying how multiple models should be merged operationally.

Detailed Summary of Technical Progress.

  1. We have developed three prototypes, explained in detail in following items. Each prototype combined two VE systems of differing complexity or functionality. In each experiment we sought to identify the various abstractions in the VE software architecture that needed to be specified for Polylith manipulation.
  2. The first prototype involved interconnecting two copies of one process, a VE allowing building walkthrough using two joysticks and flatscreen graphics. We learned which components of the VE datastructures needed to be exchanged among processes, and found that the overhead of Polylith did not degrade response time in the VE. There were no data format or function mismatches to manage.
  3. The second prototype combined the walkthrough process from prototype one with a different building walkthrough using a immersive head-mount I/O environment. There were some function mismatches that we translated with Polylith calls but the data formats were the same.
  4. The third prototype was a maze walking program that involved multiple immersive VE processes from prototype 2 and several 2-D maze walking processes (supplied by UMD, running with traditional engineering workstation screen graphics and controlled from the keyboard). This interoperating VE had different user interfaces providing views of one maze: the immersive VEs gave a 3-D view, showing the maze as a "dungeon" with stone walls floor and ceiling. Other walkers appeared as 3-D figures in the maze. The 2-D processes showed the same maze from a "floorplan" view, from above, and the locations of all walkers were seem at all times. This version has data format mismatches, user interface mismatches, and function mismatches. We experimented running this version over the Internet between UMD and UNC with acceptable results.
  5. We are developing specifications that allow compact expression of the abstractions we have identified in interconnecting the three experimental distributed VEs.

Transitions and DOD Interactions.

  1. PI is participating in an ARPA CAETI grant in which we are investigating application of MUD/MOO-style OODB methods to storage, retrieval, and manipulation of imformation required in collaborative and interoperating VEs. The CAETI work is leveraging our results from the ONR grant, and conversely we expect the results of the CAETI work to have some impact on this ONR project.

Software and Hardware Prototypes.

List of Publications.

  1. Virtual environment architectures: interoperability through software interconnection technology. P.D. Stotts and J. Purtilo. Proceedings of Third IEEE Workshop on Enabling Technologies: Infrastructure for Collaborative Enterprises, Morgantown WVa, IEEE Computer Society Press, (April 1994), pp. 211-224.
  2. J. Duff, J. Purtilo, M. Capps, and D. Stotts, "Software Engineering of Distributed Simulation Environments," submitted to Distributed Somputing Systems '96.
  3. M. Capps, J. Duff, J. Purtilo, and D. Stotts, "Engineering Interoperable Virtual Environments," submitted to VRAIS '96, San Francisco, March 1996.
  4. M. Capps, J. Duff, J. Purtilo, and D. Stotts, "Software Interconnection for Virtual Environments," submitted to Configurable Distributed Systems, Annapolis, MD, May 1996.

Invited and Contributed Presentations.

  1. Research presentation, ONR VE grantee meeting, Virginia, March 1995.
  2. Research presentation, ARPA CAETI/CAPER participants meeting, George Mason Univ., Sept. 1995.
  3. Invited talk, Computer Science Dept., William and Mary College, Williamsburg VA, April 1995.
  4. Invited talk, Computer Science Dept., Hampton Univ., Hampton VA, April 1995.

Honors, Prizes or Awards Received.

Project Personnel Promotions.

  1. Assoc. Professor Stotts (PI) was recommended for tenure at UNC in Sept. 1995, to be effective Jan. 1996.

Project Staff.

  1. Name: Dr. David Stotts

Multimedia URL.

  1. EOYL FY95
  2. QUAD FY95
  3. EOYL FY94
  4. The UNC CS Department brochure (print media) for 1995-96 for 1995-96 graduate recruiting features this project. Here is an online excerpt showing the photos from the brochure.
  5. Video Tape: We have a short (4 min) video tape available showing two of our interconnection protoypes in operation. A copy can be obtained for viewing from Dr. David Stotts


  1. software architecture
  2. module interconnection
  3. virtual environment
  4. VRML
  5. Java
  6. Polylith
  7. interoperability

Business Office


  1. Est. FY96: 100%
  2. FY95: 100%
  3. FY94: 100%
  4. FY93: N/A


  1. Name: Mr. Michael Capps

Book Plans

Sabbatical Plans

Related Research

  1. ARPA CAETI program or more specifically, UNC's CAPER part of it