Multi-user virtual reality system for simulating a three-dimensional environment

[0002] This application is a continuation under 37 C.F.R. 1.60 of a United States patent application filed by Marc de Groot in the United States Patent and trademark Office on Sep. 9, 1996, Ser. No. 60/025,684, and titled, MULTI-USER VIRTUAL-REALITY SYSTEM FOR SIMULATING A THREE-DIMENSIONAL ENVIRONMENT, and is incorporated in full herein by reference.

[0003] A portion of the disclosure of this patent document contains material which is subject to copyright protection. In particular, the several appendices are copyright 1993-1996 by Marc de Groot and Immersive Systems, Inc. The copyright owners have no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but they otherwise reserve all copyright rights whatsoever. (See, 37 C.F. R. §1.71 (d)-(e).)

[0004] The invention relates generally to computer-implemented methods and systems for network communication and participation and more specifically, to systems and methods for building, representing and interactively animating the interplay of imaginary objects in a simulated three-dimensional world.

[0005] 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.

[0006] FIG. 1 is an onion-layer diagram of a multi-user virtual reality (VR) system embodiment of the present invention;

[0007] FIG. 2 is a block diagram showing parts of the multi-user virtual reality (VR) system of FIG. 1; and

[0008] FIG. 3 is a memory map of the multi-user virtual reality (VR) system resident in a typical computer.

[0009] FIGS. 1-3 variously illustrate a multi-user virtual reality (VR) system 10 which is preferably implemented as a computer-implemented method that creates networked virtual world for real time interaction amongst multiple participants. A computer simulation is established and distributed across a computer network to participants and is pictorialized and animated as a virtual world. The simulation accommodates multiple users whose computers are preferably connected by a communications network, e.g., TCP/IP, the “internet”, etc. The respective physical types of each user's computers need not be the same type of machine. Users can interact with one another and with the objects in the virtual world. Any property of an object, including its form, color, and behavior, can be modified in real time while the simulation is running. Modifications to objects persist, even in the event of a computer system shutdown and restart.

[0010] A host computer is one of a plurality of computers physically distributed but connected by a communications network. Fach host computer is identified on the network by a unique symbol, e.g., a host ID numeric code that is preferably a 32-bit data word. The network IP number for the host can be used for the host ID.

[0011] The local host has a variety of input/output (I/O) devices with which a given human user directly interacts to experience and impact the virtual world. A local user directly interacts with a given host's I/O devices.

[0012] A dynamic module is preferably a block of binary executable code and/or data. Each such module has a predefined and standardized structure and is critically hardware-platform independent. Such modules comprise relocation information that permits values within the module to be adjusted according to the address at which it is loaded. A program entry point is included in each module for initializing and de-initializing the contents. Another program entry point is provided for the receiving and processing of messages transmitted by other modules. Each dynamic module typically represents one virtual object.

[0013] Each dynamic module has a module ID symbol that uniquely identifies it among all the other modules loaded on its host. In one embodiment, the module ID is 32-bits wide, and is the base address of the module in its host's memory.

[0014] A master module is used as the central hub for communications for the copies of a virtual object in a shared space. The master module acts as an arbiter of conflicting requests, disseminates messages to the slave copies about changes, and makes the final decision about whether to allow a modification of the virtual object. The master module runs on the host that owns the virtual object.

[0015] A slave module processes messages from the master module about changes in its appearance or other properties. The slave keeps the master informed about interactions it has with other virtual objects. The slave module cannot change its properties in direct response to an interaction. It communicates the interaction to the master and waits to be instructed to modify itself.

[0016] A quantity “hmID’ is used to uniquely identify a module among all modules in the virtual universe. The hmID is preferably a two-dimensional quantity comprised of the module ID of the module and the host ID of the host on which it is loaded.

[0017] A prism is preferably a rectangular prism, e.g., a three-dimensional solid with six sides, eight vertices and twelve edges. Every pair of edges that meet at a vertex form a right angle, e.g., a box. The prism's faces are always parallel with one of the XY, XZ, or YZ plane of the universe coordinate system. The prism is defined by giving the interval over which the prism extends when projected onto each of the X, Y and Z axes of the universe coordinate system. The notation for a prism is (X_min, X_max, Y_min, Y_max, Z_min, Z_max). A point p=(x, y, z) is considered to lie inside the prism of X_min<=P_x<X_maxand Y_min<=Py<Y_maxand Z_min<=Pz<Z_max.

[0018] A region is preferably a set of one or more prisms and regions that are contiguous.

[0019] Modules are intended to hold any sort of virtual object that can be imagined by the designer, and the specification of module functionality is open-ended. However, multi-user VR system 10 specifies some required types of modules, and specifies their behavior, to provide a framework for the virtual universe.

[0020] A deck module is the first module that runs when the system is started up, and such are responsible for reading a stored configuration and starting the other modules in the system. The deck module also acts as an initial point of contact for communications from other hosts, and provides a global repository service for data shared by many modules on a given host. The deck module has no master/slave counterparts.

[0021] A space module is used to create and manage the objects and properties in the immediate environment around a user. The immediate environment is typically the contents of one room or building. A space master module is one that creates the objects in the space that is owned by the local host. By running the module, the local host acts as a server for the space it owns. This module is not loaded if the local host owns no space. A space slave module is one that creates the objects in the space that the self experiences. The space slave module is not loaded unless there is a self master module running. Its function is to provide sensory input for the local user. If the self master module is running, there is preferably always a space slave module running. It is preferably always a slave copy of the space that the local user is in.

[0022] A view module drives the three-dimensional display of the space, and runs the task that draws the world on the monitor or in the HMD. The view module creates the camera object and the rendering task. The view module has no master/slave counterparts.

[0023] A self module implements the user's presence in the virtual universe and creates the vehicle module, the instrument panel module, and the avatar module. A self master module always runs on the user's local host. It processes input from the user via the local host's I/O devices, and sends messages to the self slave module(s) to update the avatar visible object and the instrument panel in accordance with the user's actions. A self slave module creates and manages the visible manifestation of a user, and runs on every host that is running a copy of the space that Alice, the local user, is in. For example, if Alice is the only user in the space, there is only one copy of Alice's self slave module running, and it runs on the host that owns the space. If there are other users in the space, there is one additional copy of Alice's self slave module running on each user's local host.

[0024] A vehicle module provides the “feet” for a self module, and provides the user with the ability to move around in the virtual world. A vehicle master module holds a task that takes input from the user, e.g., via the mouse, keyboard, or some other I/O device. It translates that input into commands to move. A vehicle slave module receives motion updates from the vehicle master and applies them to the self slave module. When the vehicle slave is started, it is sent a message with a pointer to the object whose position it should control. The slave responds directly to this message, because it is the slave self module that sends it.

[0025] An instrument-panel module implements the “hands” of the self module. It gives the user the ability to manipulate the objects in the virtual world. The instrument-panel module manifests as a visible object that is preferably attached to the eyepoint, and hence does not change position with respect to the viewing frustum of the camera object. The visible object is preferably an icon for a tool. The tool, when selected with a pointing device, e.g., a mouse or glove, and changes its visual properties so as to bring into view other, similar icons that represent tools for manipulating virtual objects. The icons at every level have the same behavior; they can be stacked to as many levels of depth as are practicable.

[0026] An instrument-panel master module runs a task that waits for a selection event from the pointing device. The pointing device can be used by both the vehicle module and the panel module; for this reason the panel master checks whether the selection event selected an object that is in the domain of the currently active tool. If the object is in the tool's domain, a message is sent to the vehicle causing it to suspend motion. When the selection event is finished, another message is sent to the vehicle to allow it to resume motion. An instrument-panel module slave module is used to create the visible-object tool icon. It receives messages from the panel master module to highlight and not highlight, and select and unselect the tool icon. The panel slave module changes the visual properties of the tool icon in response to these messages.

[0027] A root-tool is the first tool created by the instrument-panel module in a tool hierarchy. The root-tool can be written so it loads and unloads child tools when it is selected and unselected. A root-tool master module processes four specialized messages: highlight, not highlighted, select, and unselect. It passes such messages onto its slave counterparts so they can update the visual properties of the root-tool icon. A root-tool slave module creates and destroys the icon for the root-tool when the module is loaded and unloaded. It processes four specialized messages: highlight, not highlighted, select, and unselect. It reacts to these messages by changing a property or properties of the tool icon. The property changes are not restricted, but the color or brightness of the icon will increase when it is highlighted. So the icon will experience a visual change when selected that will be readily noticeable even after many minutes, such as a continuous animation of the icon. Any change made to the icon on highlight or selection should be reversed on not highlighted or unselection. The highlighted message is sent when the pointing device's cursor or image overlaps the icon. The not highlighted message is sent when the pointing device's “grab” state changes. In the case of a mouse, the “grab” state changes on a mouse-down or mouse-up event. For devices other than mice, the “grab” state transition is device-dependent.

[0028] An avatar is preferably a visible and audible representation of the user in the virtual world. It is the “body” of the user as s/he moves through the virtual space. An avatar master module runs a task that animates the avatar according to motion produced by the vehicle and input produced by various I/O devices such as datagloves, three-dimensional tracking devices on the hand or head, etc. An avatar slave module is used to create the visible and audible objects that represent the user in the virtual world. The avatar slave relies on the avatar master to tell it how to move and make sound.

[0029] A host can own a space. A space is preferably a completely bounded section of 3-space. Ownership of a space by a host means that the host makes the final decision about modification of any object or any property of the space.

[0030] There can be several operating modes. The deck module runs different sets of daughter modules depending on the configuration of the local host and local user. The system can be run stand-alone or connected to a network. If the network interface is disabled, the network mode is “stand-alone”, otherwise it is “networked”.

[0031] There is a distinction between owning and not owning a space in the host mode. If the local host owns a space, it must run a space master module. The space master module creates the master copies of all objects in the space. It clones slave copies of the objects when a user visits.

[0032] An inactive local user consumes no system resources. There is no need to drive the display, so neither the view module nor the space slave module are needed. The user is not present in the virtual universe, so the self module is not loaded.

[0033] The passive local user is preferably a spectator. The display is driven so the virtual world can be seen, but the user has no presence in the world. The user can neither move about nor affect the virtual world. The view module and space slave module are loaded, but the self module is not loaded. The user's eyepoint is fixed at the startup configuration position and orientation. The active local user is present in the world. The view and space slave modules are loaded to drive the display. The self module is loaded to allow movement in and manipulation of the virtual world, and to provide a visible avatar.

[0034] In the quiescent state, the column filled with the letter “Q” in the table below represents the combination of no space ownership by the host and an inactive user. In such a situation, only the deck module is loaded. The deck module executes no code. It waits in a quiescent state. If it receives a message that the local host has become the owner of a space, the deck starts the Space_Mmodule, which is the server for the owned space.

[0035] Table I illustrates operating modes and associated modules. Check marks indicate modules that are loaded. Gray columns indicate impossible modes. Q in a column indicates the quiescent state.

[0036] The startup configuration carries four pieces of data:

[0037] 1. the network mode, “stand-alone” or “networked”’

[0038] 2. the host mode, “host owns a space” or “host doesn't own a space”;

[0039] 3. the user mode, “inactive”, passive”, or “active”; and

[0040] 4. the initial user position/orientation, given as a three-dimensional point in world coordinates, and three angles in degrees for yaw, pitch and roll.

[0041] The deck module determines the startup configuration for the host. It checks the network mode first. The network mode is “stand-alone” if VR services program started with its network interface disabled, otherwise the mode is “networked”. If stand-alone, space ownership is preferably assumed. If networked, the deck queries the space-to-host server to determine the host mode, either “host owns a space” or “host doesn't own a space”. It reads the user mode and initial position/orientation from stored data (perhaps a disk file).

[0042] On startup, the deck loads modules in accordance with the startup configuration. The stand-alone configuration is used when the connection to the network is non-existent or has been disabled. The stand-alone configuration must run in owned-space host mode, because the master module for the space will not run otherwise and it is impossible to have a slave module run without its master. The stand-alone configuration must run in passive or active user mode, otherwise it is preferably a zero-user space with no network connection through which a user could enter the space.

[0043] Table II represents the module used for atypical stand-alone configuration

[0044] The networked active-user-at-home configuration is the most common startup type. The system is started with the local user in the local host's owned space.

[0045] Table III shows the modules used for a typical active-user-at-home configuration. The list of modules for a typical active-user-at-home is identical to the list for a stand-alone configuration

[0046] The networked active-user-visiting-elsewhere configuration is the second most common startup type. The system is started with the local user in a space owned by another host.

[0047] The list of modules used for a typical active-user-visiting-elsewhere configuration differs from the above examples because more than one host is involved. It is assumed that there is only one user in the space being visited, e.g., the local user from this host. The difference is that the slave space module was downloaded from the remote host, and has created visible objects depicting the space owned by that host.

[0048] The steps used for starting up a multi-user VR system node are represented here in pseudocode, e.g., Table V. The modules started are limited to those listed in the Module types section of this document. This sequence of steps will start a multi-user VR system 10 node in any of the valid configurations.

[0049] A programming guide for the VR services program (MEME and several example module codes are attached hereto to provide further understanding of the described mechanisms and to aid in their implementation.

[0050] Although the present invention has been described in terms of the presently preferred embodiments, it is to be understood that the disclosure is not to be interpreted as limiting. Accordingly, it is intended that the appended claims be interpreted as covering all alterations and modifications as fall within the true spirit and scope of the invention.