Michael Zyda

From visual simulation to virtual reality to games

During the past decades, the virtual reality community has based its development on a synthesis of earlier work in interactive 3D graphics, user interfaces, and visual simulation. Currently, the VR field is transitioning into work influenced by video games. Because much of the research and development being conducted in the games community parallels the VR communitys efforts, it has the potential to affect a greater audience. Given these trends, VR researchers who want their work to remain relevant must realign to focus on game research and development. Leveraging technology from the visual simulation and virtual reality communities, serious games provide a delivery system for organizational video game instruction and training.

Npsnet: A network software architecture for largescale virtual environments

This paper explores the issues involved in designing and developing network software architectures for large-scale virtual environments. We present our ideas in the context of NPSNET-IV, the first 3-D virtual environment that incorporates both the IEEE 1278 distributed interactive simulation (DIS) application protocol and the IP multicast network protocol for multiplayer simulation over the Internet.

An extended Kalman filter for quaternion-based orientation estimation using MARG sensors

Presents an extended Kalman filter for real-time estimation of rigid body orientation using the newly developed MARG (magnetic, angular rate, and gravity) sensors. Each MARG sensor contains a three-axis magnetometer, a three-axis angular rate sensor, and a three-axis accelerometer. The filter represents rotations using quaternions rather than Euler angles, which eliminates the long-standing problem of singularities associated with attitude estimation. A process model for rigid body angular motions and angular rate measurements is defined. The process model converts angular rates into quaternion rates, which are integrated to obtain quaternions. The Gauss-Newton iteration algorithm is utilized to find the best quaternion that relates the measured accelerations and earth magnetic field in the body coordinate frame to calculated values in the earth coordinate frame. The best quaternion is used as part of the measurements for the Kalman filter. As a result of this approach, the measurement equations of the Kalman filter become linear, and the computational requirements are significantly reduced, making it possible to estimate orientation in real time. Extensive testing of the filter with synthetic data and actual sensor data proved it to be satisfactory. Test cases included the presence of large initial errors as well as high noise levels. In all cases the filter was able to converge and accurately track rotational motions.

A taxonomy for networked virtual environments

We discuss virtual environments in the context of how to distribute network communications, views, data, and processes while emphasizing those aspects critical to scaling environments. Systems that demand strong data consistency, causality, and reliable communications while supporting real-time interaction are not likely to scale very well. Furthermore, geographically dispersed systems require high-speed, multicast communication.

Simplification of objects rendered by polygonal approximations

Abstract Current technology provides a means to obtain sampled data that digitally describes three-dimensional surfaces and objects. Three-dimensional digitizing cameras can be used to obtain sampled data that maps the surface of three-dimensional figures and models. Data obtained from such sources enable accurate renderings of the original surface. However, the digitizing process often provides much more data than is needed to accurately recreate the surface or object. In order to use such data in real-time visual simulators, a significant reduction in the data needed to accurately render the sampled surfaces is required. The techniques presented were developed to drastically reduce the number of data points required to depict an object without sacrificing the detail and accuracy inherent in the digitizing process.

Inertial and magnetic posture tracking for inserting humans into networked virtual environments

Rigid body orientation can be determined without the aid of a generated source using nine-axis MARG (Magnetic field, Angular Rate, and Gravity) sensor unit containing three orthogonally mounted angular rate sensors, three orthogonal linear accelerometers and three orthogonal magnetometers. This paper describes a quaternion-based complementary filter algorithm for processing the output data from such a sensor. The filter forms the basis for a system designed to determine the posture of an articulated body in real-time. In the system the orientation relative to an Earth-fixed reference frame of each limb segment is individually determined through the use of an attached MARG sensor. The orientations are used to set the posture of an articulated body model. Details of the fabrication of a prototype MARG sensor are presented. Calibration algorithms for the sensors and the human body model are also presented. Experimental results demonstrate the effectiveness of the tracking system and verify the correctness of the underlying theory.

NPSNET : hierarchical data structures for real-time three-dimensional visual simulation.

Abstract 3D visual simulation systems must present a world, including terrain, cultural features, and 3D icons, in real-time at a level of detail that supports the use for which the system is intended. A “simple” world lends itself to blasting all the polygons through the workstations existing graphics pipeline. However, a “simple” world is not very realistic and/or does not operate in real-time. For complex worlds, such as that modeled in NPSNET, providing high fidelity in real-time requires the use of hierarchical data structures. We explore the implementation of such a structure on the world modeled by NPSNET utilizing quadtrees.

Bamboo-a portable system for dynamically extensible, real-time, networked, virtual environments

Bamboo is a portable system supporting real-time, networked, virtual environments. Unlike previous efforts, this design focuses on the ability of the system to dynamically configure itself without explicit user interaction, allowing applications to take on new functionality after execution. In particular, this framework facilitates the discovery of virtual environments on the network at runtime. Fundamentally, Bamboo offers a compatible set of mechanisms needed for a wide variety of real-time, networked applications. Also included is a particular combination of these mechanisms supporting a dynamically extensible runtime environment. This paper serves as a general introduction to Bamboo. It describes the systems architecture, implementation and future directions. It also shows how the system can facilitate the rapid development of robust applications by promoting code reuse via community-wide exchange.

NPSNET: a multi-player 3D virtual environment over the Internet

in the Proceedings of the 1995 Symposium on Interactive 3D Graphics, 9 - 12 April 1995, Monterey, California.

NPSNET: flight simulation dynamic modeling using quaternions

The Naval Postgraduate School (NPS) has actively explored the design and implementation of networked, real time, three-dimensional battlefield simulations on low-cost, commercially available graphics workstations. The most recent system, NPSNET, has improved in functionality to such an extent that it is considered a low-cost version of the Defense Advanced Research Project Agencys (DARPA) SIMNET system. To reach that level, it was necessary to economize in certain areas of the code so that real time performance occurred at an acceptable level. One of those areas was in aircraft dynamics. However, with off-the-shelf computers becoming faster and cheaper, real-time and realistic dynamics are no longer an expensive option. Realistic behavior can now be enhanced through the incorporation of an aerodynamic model. To accomplish this task, a prototype flight simulator was built that is capable of simulating numerous types of aircraft simultaneously within a virtual world. Besides being easily incorporated into NPSNET, such a simulator also provides the base functionality for the creation of a general purpose aerodynamic simulator that is particularly useful to aerodynamics students for graphically analyzing differing aircrafts stability and control characteristics. This system is designed for use on a Silicon Graphics workstation and uses the GL libraries. A key feature of the simulator is the use of quaternions for aircraft orientation representation to avoid singularities and high data rates associated with the more common Euler angle representation of orientation.