Abstract: A computer-implemented multi-user virtual reality system that erects a networked virtual world for real time interaction amongst multiple participants. A computer-simulation of an animated world is network-distributed amongst participants, e.g., as a virtual world. The simulation accommodates multiple users whose computers are connected by a communications network. The users' computers need not be the same type of machine. Users can interact with one another and with the objects in the virtual world. The properties of objects in the virtual world, such as form, color, and behavior, are displayed on monitors and can be modified in real time while the simulation is running. Modifications to objects are stored and therefore persist, and can therefore bridge across computer system shutdowns and restarts.

Abstract: A sourceless orientation sensor having an azimuthal sensor which determines the azimuthal orientation relative to a planetary magnetic field, and a tilt sensor which determines the direction and magnitude of the displacement from vertical using the planetary gravitational field. The tilt sensor includes a transparent gas and a transparent viscous fluid in a spherical shell, a light emitting diode (LED) mounted at the top of the shell, and four photodetectors mounted at the bottom of the shell. As the tilt sensor is rotated the path of the light cone emanating from the LED and refracting at the gas/fluid interface is altered, thereby altering the intensity of light incident on the photodetectors. The magnitude of the light incident on the photodetectors is processed to provide the tilt angles. A thin transparent disk floats at the gas/fluid interface to damp surface waves caused by reorientation of the device.