Abstract:
A method and apparatus for observing exhibit sites which provides the ability to overlay computer generated images and sound on a live exhibit to create and present these overlays on demand in varying levels of detail for use by the general public, in indoor and outdoor settings, without requiring instruction, operators, fitting, training, or supervision. The viewing device may comprise a viewing portion, a processing portion, a displaying portion, and an audio portion. Each of these components combine to provide the user with the ability to view an actual exhibit site overlaid with informational or historic re-creations to enhance the exhibit experience, as opposed to a separate display booth or other means which takes the exhibit viewer&#39;s attention away from the actual exhibit site.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/039,040, filed Feb. 24, 1997. 
    
    
     1. Technical Field 
     This invention relates to an interactive viewing aid. More particularly, this invention relates to a device that provides a method and apparatus for navigating a viewer in multiple degrees of freedom while it presents a live exhibit integrated with position-correlated, computer-generated sound and visual effects. Additionally, this method and apparatus enables on-demand presentation of overlays that can be operated and controlled by the unskilled public. 
     2. Background of the Invention 
     Many historical, natural, and physical exhibit sites, such as exhibit sites found in state parks, rely on kiosks, simple poster art, or human narration to convey the historical events that occurred at the exhibit site. Although cost-effective, these exhibit aids fail to provide visitors with realistic re-enactments of historical events that are staged on the actual exhibit site. In fact, only “human-intensive” re-enactments, such as those performed at Civil War battle sites using actors, provide visitors with an effective “site-staged” presentation of historical events. However, these human-intensive re-enactments are expensive, difficult to schedule, and often result in damage to the exhibit site. When re-enactments are scheduled, visitors often flock to the exhibits sites creating congestion problems within the exhibit site. For these reasons, human re-enactments are rarely scheduled at exhibit sites. 
     Moreover, the human-intensive re-enactment methods cannot be used to recreate natural phenomena such as the eruption of Mount St. Helen&#39;s, mythical encounters such as sightings of the Loch Ness Monster, or human achievements such as the construction of Mount Rushmore. For those types of exhibits, exhibitors typically rely on films, photographs, or animation to re-create the historical events. However, instead of focusing the visitor&#39;s attention on the exhibit site, those exhibit aids typically direct the viewer&#39;s attention to a TV monitor. Thus, there is a need for an exhibit aid which provides re-enactments with exceptional realism, while maintaining the visitor&#39;s interest focused on the exhibit site. There is a further need for an exhibit aid that does not require a “human-intensive” re-enactment. 
     Exhibit aids for viewing exhibit sites, other than those described above, are also available. One exhibit aid sometimes used is a coin-operated magnification device. For example, the magnification device may be installed on a scenic overlook or a tall building to allow users a magnified view of the natural settings. Although these magnification devices do provide a magnified view of the present-day exhibit site to the user, they do not re-create or re-enact historical events at the actual exhibit site. Thus, there is a need for an exhibit aid that provides a view of the exhibit site and presents an historical re-enactment in conjunction with the magnified view. 
     Virtual reality head-mounted displays or boom-mounted virtual reality devices are sometimes used as exhibit aids. However, these virtual reality devices do not interact with the present-day exhibit site to provide the user with an historical re-enactment. Moreover, these virtual reality devices are typically not rugged enough for long-term use in seasonal outdoor environments. Thus, there is a need for a rugged viewing device that creates virtual reality re-enactments in conjunction with an actual exhibit site. 
     There are known processes for generating computer images for real-time overlay on natural sites through user driven free navigation. For example, there are several ongoing military applications that provide this capability for infantry training applications. However, all known products of this type use expensive liquid crystal display (LCD) technology for overlaying the imagery. Furthermore, none of those existing devices enable the use of low cost technologies that can also be interchanged with higher end components for virtual reality overlays. Moreover, none of these processes have integrated the overlay-process with synchronized audio and video effects processing. Existing technology is not integrated into an exhibit aid structure to allow the public to interact with it, nor does it facilitate a structured procedure to allow visitor interaction Existing devices also do not support physically removable content. Thus, there is a need for an inexpensive exhibit aid that overlays computer-generated images onto a viewed image to provide a suitable device and procedure for user interactions, field replaceable content, and applications of synchronized audio and video effects processing. 
     SUMMARY OF THE INVENTION 
     The present invention satisfies the above described needs by providing an apparatus and method for allowing the public to operate an exhibit aid device that overlays computer-generated visual and audio effects onto a live image. Embodiments of the invention allow virtual reality re-enactments and augmented reality re-enactments that can be presented on-demand to users. 
     Aspects of the invention enable users to interact with an exhibit site better than prior art exhibit aids. Aspects of the invention allow users to view the actual exhibit site through a viewing device and create on-demand re-enactments at points of interest in the exhibit site. While viewing the exhibit site, it may be determined which location the person is viewing and visual and audio information may be presented to the user including simulation of effects, historical film footage overlays, and tutorial type animation of important facts. These capabilities have never before been available for operation and presentation to users while a user is examining the actual exhibit site. Only the present invention provides a device suitable for public use (indoors and outdoors) and a procedure that can allow users to interactively operate and request overlay effects that can embellish what is seen by the naked eye and heard by the unaided ear to make the exhibit site appear as it did or will in another time. 
     In one aspect, the invention operates by providing a viewing device including a viewing portion known as an image head. The user inserts a token if the invention is configured to require such. After inserting a token, the user may step up to the viewing portion, aim it at any point of interest in the exhibit site, and push a start button. When the user pushes the start button, a timer displays the viewing time remaining. The viewing device initializes by determining its position relative to its initial orientation and determines the animated content that needs to be displayed to the user. The viewing device then provides a natural “through-the-lens” view of the exhibit site. An audio narration sequence may begin to tell the viewer about the exhibit site. Information is provided to guide the user to the proper viewing point on the exhibit site. As the proper viewing point becomes visible or centered in the viewing screen, the viewing device recognizes the user&#39;s request for additional information. The viewing device may then display computer-generated effects over the “through-the-lens” view of the exhibit location. 
     In another aspect, the invention is an exhibit viewing device including an image head for housing an integrated electronics system. The integrated electronics system is re-configurable for the dynamic and correlated generation and overlay of visual and audio effects onto a natural light source exhibit viewed through the exhibit viewing device. The exhibit viewing device also includes a head mount for user-controlled navigation of the image head. The exhibit viewing device may also include a stand connected to the head mount for stability of the exhibit viewing device and user access to the exhibit viewing device. The integrated electronic system may be operative to generate audio signals and the image head may include a speaker system for broadcasting the audio signals. 
     In still another aspect, the exhibit viewing device may include a position tracking system for determining the viewing elevation and viewing azimuth of the exhibit viewing device so that the visual effects may be coordinated, generated and overlaid onto the proper natural light source exhibit viewed through the exhibit viewing device. Among other devices, the position tracking system may comprise an electromagnetic measurement device or digital shaft encoders. 
     In still other aspects, the integrated electronics system of the viewing device may include an optical unit for overlaying the visual effects onto the natural light source exhibit. In still another aspect, the invention is a method for overlaying a computer-generated image onto a viewed image of an exhibit site in an electronic system for viewing the exhibit site incorporated into a viewing device. A position of the viewing device is determined. A user of the viewing device is guided to move, or freely guides, the viewing device to a particular location of the exhibit site. Computer animation and sound are generated regarding the particular location of the exhibit site. The computer effects are overlaid onto a lens view of the viewing device. The method may also include determining whether a token has been inserted into the viewing device before determining the position of the viewing device. 
     In still other aspects, the method may include providing audio effects and the lens view to the user before guiding the user to move the viewing device. The step of guiding the user of the viewing device to move the viewing device to a particular location of the exhibit site may comprise displaying arrows on the lens view of the viewing device. The arrows may correspond to the direction which the user should move the viewing device to reach the particular location. 
     In another aspect, the invention provides a unique device that is suitable for public use in parks, museums, restaurants, schools, science centers, and other high-traffic, low-supervision areas. The device utilizes a rugged design to encase electronic parts in a base enclosure and image head to ensure their protection. The device provides a durable method for navigating in two dimensions and allowing the collection of orientation data for computer processing; a durable housing for a pointable viewer having speakers, computer displays, electronic speakers and switches, position measurement devices, image capture equipment, computer processing, image integration and control storage. 
     In another aspect, the invention provides a unique device that allows the user to interactively browse and select information interpretations from live views of exhibits. The device allows users to navigate in azimuth and elevations while maintaining the accuracy of computer-generated positional overlays. The device provides a unique intuitive approach that does not require training or assistance. The device presents computer-generated information as the user browses over the exhibit and positions the center of view over an area of interest. The device also offers additional information upon request by the user. The device responds to user requests for additional information. The device presents tables indicating additional information. If the user positions the device over the indicator and activates the information, by pushing a button, the device may present expanded information overlays. 
     In another aspect of the system, the device offers a unique focusing aid. As the user pans to an area of interest, the device measures the orientations to determine the location of interest and automatically adjusts the magnification and other camera options, such as backlight, to clearly present the exhibit and the computer-generated imagery. This unique function of the invention allows it to present interpretations and interactive data for multiple exhibit items at varying distances from the invention. 
     In another aspect, the device can be networked to allow augmented reality interactive gaming, such that linked devices present users with consistent views of live exhibits with computer-generated overlays. For example, multiple devices can be positioned around an operational exhibit, such as a train depot, gold mine, dam, mill, factory, or assembly line, and allow each individual user to operate some aspect of the exhibit that, when combined with the other users, allows the group to virtually operate the exhibit. The invention utilizes a network to exchange the activation by each user among devices, so that a consistent view is provided by each device. 
     These and other features, advantages, and aspects of the present invention may be more clearly understood and appreciated from a review of the following detailed description of the disclosed embodiments and by reference to the appended drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are illustrations of a side view and a front view, respectively, of a viewing device in accordance with an embodiment of the present invention. 
     FIG. 1C is an illustration of a processing system which contains the electronic components that generate video overlays and audio signals for the viewing device. 
     FIG. 1D is an illustration of an alternate power supply of the viewing device. 
     FIGS. 2A and 2B are illustrations of a side view and a front view, respectively, of an image head, a head mount, and a stand of the viewing device. 
     FIGS. 3A and 3B are illustrations of a side cutaway view and a front cutaway view, respectively, of an image head detailing the internal construction of the image head. 
     FIGS. 4A and 4B are illustrations of a side view and a side cross-sectional view, respectively, of a platform base. 
     FIG. 5 is a functional block diagram of the processing system for an embodiment of the present invention. 
     FIG. 6 is a conceptual illustration of a visual image presented to the user of an embodiment of the present invention. 
     FIG. 7 is a data flow diagram illustrating the data flow of the viewing device. 
     FIG. 8 is an illustration of an optical unit incorporating a chroma-key mixer and video monitor combination in accordance with an embodiment of the present invention. 
     FIG. 9 is an illustration of an optical unit incorporating a mirror-based viewer with a simple beam splitter filter in accordance with an embodiment of the present invention. 
     FIG. 10 is an illustration of an optical unit incorporating a LCD filter-based viewer in accordance with an embodiment of the present invention. 
     FIG. 11 is an illustration of an optical unit of an embodiment of the present invention incorporating field-of-view expansion technology. 
     FIG. 12 is an illustration of an optical unit of an embodiment of the present invention incorporating optical stereo technology. 
     FIG. 13 is a flowchart illustrating a method for overlaying computer-generated images over a viewed image in accordance with an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     The present invention is directed toward a method and apparatus for overlaying computer-generated animation onto an image viewed through a magnifying viewing device. Embodiments of the invention allow virtual reality re-enactments and augmented reality re-enactments that can be presented on-demand to users through a magnifying viewing device. 
     The invention enables users to interact with the exhibit site better than prior art exhibit aids. The invention allows users to view the actual exhibit site through a viewing device and create on-demand re-enactments at points of interest in the exhibit site. While viewing the exhibit site, the invention may determine the location the person is viewing and may present visual and audio information including simulation of effects, historical film footage overlays, and tutorial type animation of important facts. These capabilities have never before been available for presentation to users while the users are examining the actual exhibit site. Prior art exhibit sites require visitors to view poster art or TV monitors that replace the exhibit site. Only the present invention can embellish what is seen by the naked eye to make the exhibit appear as it did or will in another time. 
     In one embodiment, the invention operates by providing a viewing device including a viewing portion called an image head. The user inserts a token if the invention is configured to require such. After inserting a token, the user may step up to the viewing portion, aim it at any point of interest in the exhibit site, and push a start button. When the user pushes the start button, a timer displays the viewing time remaining. The viewing device initializes by determining its position relative to its initial orientation and determines the animated content. The viewing device then provides a natural “through-the-lens” view of the exhibit site. An audio narration sequence may begin to tell the viewer about the exhibit site. Information is provided to guide the user to the proper viewing point on the exhibit site. As the proper viewing point becomes visible or centered in the viewing screen, the viewing device recognizes the user&#39;s request for additional information. 
     The viewing device may then generate a computer animation of an historical event or other pertinent information depending on the particular exhibit site. The viewing device will then overlay the computer animation on the actual through-the-lens visual image of the exhibit site being viewed by the user. This provides the user with the illusion that he is watching an actual re-creation of some historical event at the exhibit site. While the user is viewing the re-created events, the narration continues, and may be supplemented with sound effects, such as explosions, cannon fire, or other appropriate sounds. Finally, the timer expires and the presentation terminates. 
     In alternative embodiments, an overlay may be generated which includes “hot-spots,” or areas on the viewing screen that mark points of interest to many viewers. By navigating the viewing device to a hot-spot, the user may be provided with additional information about that particular point of interest on the exhibit. 
     While aspects of the present invention will be described in the general context of computer programs that run on an operating system in conjunction with a computer, those skilled in the art will recognize that, generally, computer programs include routines, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Referring now to the drawings, in which like numerals represent like elements throughout the several figures, aspects of the present invention will be described. 
     Referring now to FIGS. 1A and 1B, a side view and a front view, respectively, of a viewing device  100  in accordance with an embodiment of the present invention will be described. The viewing device  100  consists of an image head  110 , a head mount  120 , and a stand  130 . 
     The image head  110  houses a processing system  140  (illustrated in FIG. 1C) which contains the electronic components that generates video overlays and audio signals. 
     The head mount  120  holds the image head  110  in place. The viewing device  100  also includes handles  160  protruding from each side of the image head  110  to allow movement of the image head  110 . The handles  160  are generally cylindrical in shape and include a shaft portion  165  that extends through holes in the head mount  120  to connect the image head  110  to the head mount  120 . By moving the handles  160 , a user may change the viewing azimuth and elevation of the image head  110 , thereby changing the image viewed by a user. The head mount  120  is mounted atop stand  130  and rotates about the axis of stand  130  to change the viewing azimuth. The handles  160  rotate the image head  110  about the axis of the handles  160  to change the viewing elevation of the image head  110 . An assembly  170  that connects the base of the head mount  120  to the top of the stand  130  allows the image head  110  and head mount  120  to rotate about the axis of stand  130 . 
     The viewing device  100  may also include an auxiliary power supply  150  as illustrated in FIG.  1 D. 
     Referring now to FIGS. 2A and 2B, a side view and a front view, respectively, of an image head  110 , head mount  120 , and stand  130  of viewing device  100  will be described. The image head  110  includes a face  210  and a back  220  that are preferably connected together by bolts. The viewing device  100  preferably has a modular construction which allows components to be mixed and matched to optimize the viewing device to an individual&#39;s customer price and performance requirements. 
     The head mount  120  is secured to the stand  130  with bolts  230 . The head mount  120  is secured to the image head  110  by the handles  160 . Bearings  240  allow the head mount  120  to rotate about the stand  130 . The stand  130  may be constructed as a steel pole. Power may be fed to the electrical components within the image head  110  through a duct  250  in the head mount  120  and then through the handles  160 . 
     Referring now to FIGS. 3A and 3B, a side cross-sectional view and a front cross-sectional view, respectively, of image head  110  will be described. The image head  110  houses a speaker system  310  that is positioned near the point where the user&#39;s ears are when operating the viewing device  100 . The positioning of the speaker system  310  allows low volume audio play that is easily heard by the user. The volume may be controlled with an optional toggle button  320 . 
     A position tracking system  330 , or  3301  and  3302 , monitors the orientation data (pitch and yaw movement) of the image head  110  and feeds the orientation data to the processing system  140 . The processing system  140  processes the orientation data to calculate the orientation of the viewing device  100  so that computer-generated images may be generated for overlaying. The position tracking system  330  may be an electromagnetic measurement device located in the image head  110 . Alternatively, the position tracking system  3301 ,  3302  may comprise shaft encoders located in the two axes on which the image head  110  rotates. 
     The processing system  140  generates computer-generated images and transmits these images to an optical unit  350  for overlay onto the natural view. A start switch  360  powers up and initiates the viewing sequence within the processing system  140 . An optional I/O interface  370  allows uploading of additional content, such as visual models, sound effects, and viewing vignettes, to the processing system  140 . 
     Still referring to FIGS. 3A and 3B, the image head  110  may further comprise a left hand housing  365  and a right hand housing  375  connected together with bolts  377  and separated by a housing seal  380 . In addition to the housing seal, the image head  110  may further comprise a viewer seal  382 , an I/O interface seal  384 , a start switch seal  386 , and a volume control seal  388 . These seals are preferably composed of rubber, but may be composed of a similar substance with sealing properties. These seals provide moisture protection for the internal components of the image head  110  so that it may properly function outside in the elements without breakdowns. 
     The image head  110  may also comprise a cooling fan  390  and a power converter  395 . A viewer  399 , preferably composed of glass, is typically situated between the speaker system  310 . The viewer  399  is similar to the lenses of binoculars and allows the user to view a magnified image of an exhibit site or similar terrain. 
     Referring now to FIGS. 4A and 4B, a side view and a side cross-sectional view, respectively, of a platform base  400  will be described. The platform base  400  typically is a multi-tiered device at the base of the stand  130  that enables users of varying heights to view the exhibit without adjusting the height of the viewing device  100 . The stand  130  may be attached to the platform base  400  with bolts  420 . The platform base  400  comprises multiple tiers  430  which act as steps for users of different heights. Power conduits  440 , typically composed of PVC, may extend from the bottom of the platform base  400 . The power conduits  440  allow power cables to be fed up through the stand  130  to the image head  110 . In alternative embodiments of the present invention, the power supply to the invention could be a DC power supply contained in a chamber below the platform base  400  or within the image head  110  itself. 
     Referring now to FIG. 5, a functional block diagram of the processing system  140  for an embodiment of the present invention will be described. The processing system  140  begins processing when a user presses the start button  360 , which triggers an optional vending system  575 . In most embodiments, the vending system  575  will be the mechanism for accepting coins, tokens, or other payment to initiate a viewing session using the viewing device  100 . It should be understood that the vending system may take a number of different devices, such as credit cards, check cards, other magnetic strip cards, or any other form of payment. After a coin is inserted into the vending system  575  and the start button  360  is pressed, a signal is sent to the computer system  510 . In response to the signal indicating that a coin has been inserted and the start button pressed, the computer system  510  will initiate presentation of content to the user. It should be understood by those skilled in the art that the computer system  510  may typically be integrated into the image head  110  or located at the platform base  400 . If located at the platform base  400 , the computer system  510  is housed with a protective cover, rests on the slab of the platform base  400 , and interfaces with the image head  110  via electrical wiring running up the stand  130 . 
     After a viewing sequence has been initiated, the computer system  510  polls the position tracking system  330 , which is connected to an image generation computer  511  by a port #1  519 , to determine the orientation of the viewing device  100 . A diagnostic system  576  may be provided to ensure that each of the components of the processing system  140  is functioning properly. 
     After the orientation information has been determined, the image generation computer  511  polls a content storage device  580  to determine the viewing sequence that needs to be displayed to the user. The content storage device  580  may be an EPROM, an EPROM, a computer disk, an optical compact disk, or another mass storage medium. The content storage device  580  stores the information, such as computer-generated images, which will be overlaid on the natural view of the exhibit. 
     It should be understood that while the viewing sequences retrieved from the content storage device  580  are playing, the computer system  510  is receiving visual input from an optics system  530  via an I/O controller  515  and an expansion bus interface  514 . The image generation computer  511  aligns and merges the viewing sequences, such as animation, retrieved from the content storage device  580  with the natural-view visual input received from a lens  532  of the optics system  530 . The computer system  510  then outputs the merged visual image, via a video output  513 , to a monitor  531 . The user may optionally manually configure various display characteristics of the monitor  531 , such as brightness or contrast, for maximum viewing enjoyment. Other embodiments of this invention will utilize digital image processing to determine these requirements and make automatic adjustments for them. 
     Simultaneously with the visual output, the computer system  510  may output synchronized audio signals, via audio outputs  516 , to accompany and enhance the visual output. The audio signals may be stored in the content storage device  580 . The audio system  550  receives the audio signals at audio inputs  552  of a stereo amplifier  551 . The stereo amplifier  551  amplifies and outputs the audio signals to the speaker system  310  for the user&#39;s listening. The user may control the volume of the audio by actuating the optional volume button  320 , which signals the volume control  554  of the audio system  550 . The stereo amplifier  551  may be located in the image head  110  or integrated into the computer system located at the platform base  400 . 
     A power system  590  provides power to each of the components of the processing system  140  via various power interfaces  591  at each component. The power system  590  may be either an AC power source and transformer or a DC power source, or combination of the two systems. A backup power source may also be implemented. In some embodiments, the system will retain the primary power supply at the base of the system or at some remote location, and only supply a low current electrical supply to the imaging head to ensure user safety. 
     Referring now to FIG. 6, a conceptual illustration of a visual image presented to the user of an embodiment of the present invention will be described. Embodiments of the present invention use unique processes to determine a user&#39;s interest and present a tailored presentation of the script while simultaneously controlling magnification levels, audio and animation effects, and synchronizing these effects with the user&#39;s free navigation of the viewing device  100 . FIG. 6 depicts a representative exhibit, in this case a volcano, as seen through the viewing device  100  with informational details overlaid on the through-the-lens viewfinder imagery. As illustrated in FIG. 6, the device generates an overlay to make the volcano appear as it did prior to the eruption. The overlays are positioned and scaled accurately to provide a re-created view that is a mix of reality and computer-generated imagery. The overlays are time-sequenced and coupled with audio effects and narration to create an educational experience. 
     Referring now to FIG. 7, a data flow diagram depicting the data flow of viewing device  100  is illustrated. The data flow may be implemented in software that runs within the processing system  140  of the viewing device  100 . Additional procedures may operate on peripherals connected to the processing system  140 . The bubbles within FIG. 7 represent software functions. The lines within FIG. 7 represent data flow. The arrows in FIG. 7 show the direction of the data flow. Each line is labeled with the data that is transferred. The cylinders in FIG. 7 represent databases used by the software. 
     The key software component of the viewing device  100  is the content manager  710 . The content manager  710  is typically the primary decision maker for the viewing device  100 . The content manager  710  receives input from other software functions and generates outputs to other functions. The content manager  710  initiates when it receives a start signal from the start detect  720  routine. The content manager  710  then sends a start signal to a clock  730  and loads a first event from an event player  740 . Depending on the event loaded, the content manager  710  may set a time limit for a timer  750 , load a point of interest from a points of interest player  760 , or load the viewing device position from a position monitor  770 . As the content manager  710  continues to process inputs from the event player  740 , the point of interest player  760 , and the position monitor  770 , it generates data for an audio generator  780  and a scene generator  790 . 
     The content manager  710  sends the current location, events, and points of interest to the scene generator  790 . The content manager  710  sends the current location and sounds to the audio generator  780 . 
     The unique content, such as computer-generated images, for different embodiments of the present invention is stored in a content database  791 . The content database  791  comprises data representing all of the events and points of interest for the viewing device  100 . A content database reader  792  extracts the content data from the content database  791  and sends the event data to the event player  740  and the data representing location of points of interest to the points of interest player  760 . The event player  740  processes the events data based on the time it receives from the clock  730 . The points of interest player  760  processes points of interest data based on the position and orientation it receives from the position monitor  770 . Both the event player  740  and the points of interest player  760  transmit data to the content manager  710 . 
     Visual models and virtual world models unique to each embodiment of the present invention are stored in a visual models database  793  and a virtual world database  794 . The visual models and virtual world models are read by a model loader  795  using a database format. The model loader  795  converts the models in database format to an appropriate digital format and sends the model and terrain information to a visual rendering  796 . 
     The scene generator  790  receives location, points of interest, and events from the content manager  710 . Based on the events and location, the scene generator  790  determines what objects are in the scene. The objects and location are sent from the scene generator  790  to the visual rendering  796 . Visual rendering  796  receives the objects and locations and selects the appropriate models and terrain. The models and terrain are converted to geometry, textures, and animations and sent to a graphics driver  797 . The graphics driver  797  displays the geometry, textures, and animations to the user over the viewed image. 
     The sounds unique to each embodiment of the present invention are stored in sound files in an audio database  781 . The sound files are read from the audio database  781  by an audio loader  782 . The audio loader  782  sends the sound files in the appropriate digital format to the audio generator  780 . The audio generator  780  receives the names of sounds and locations from the content manager  710 . Using this information, the audio generator  780  creates sound signals, such as stereo, digital, specialized, and surround, that are sent to an audio driver  783 . The audio driver  783  then plays the sounds for the user. 
     An I/O port handler  712  is also included in the viewing device  100 . The I/O port handler  712  preferably has two modes, setup and run. In setup mode, the I/O port handler  712  sends user input to a setup tool  711 . The setup tool  711  stores the location of the viewing device  100  in a position database  771 . The position monitor  770  receives the location of the viewing device  100  from the position database  771 . In run mode, the I/O port handler  712  sends the orientation of the viewing device  100  to the position monitor  770 . The position monitor  770  sends the position to the content manager  710  and the position and orientation to the points of interest player  760 . 
     The timer  750  receives a time limit from the content manager  710  and sends the time left to the content manager  710 . The content manager  710  sends commands for peripherals connected to the invention to an I/O controller driver  713 . These commands may include brightness, contrast, and zoom. 
     Turning now to FIGS.  8 - 10 , it should be understood that the optical unit  350  for the viewing device  100  may have several different options in order to support multiple price and performance requirements of purchasers. 
     Referring now to FIG. 8, an illustration of an optical unit  350  in accordance with an embodiment of the present invention will be described. The optical unit  350  may comprise a display and mixer based viewer driven by a mixer  805  that integrates computer generated images and camera generated video. The mixer  805  may typically be a Chroma-key mixer or a computer digital mixer. The mixer  805  receives a National Television Standards Committee (NTSC) video signal  810  from a video camera  820  directed at an exhibit site  825 . The mixer  805  also receives a VGA overlay signal  815  from the image generation computer  511 . The mixer  805  mixes the NTSC video signal  810  with the VGA overlay signal  815  and outputs an output NTSC video signal  830  to a monitor  835  so that it may be viewed by a viewer  840 . In the mixing process, all of the VGA data is displayed instead of the NTSC data, except where the VGA data is “blue background”. The VGA background imagery is not overlaid on the NTSC data, thus creating an augmented image. 
     Referring now to FIG. 9, another illustration of an optical unit  350  in accordance with an embodiment of the present invention will be described. The optical unit  350  may comprise a mirror-based viewer, as shown in FIG.  9 . The optical unit  350  may integrate a display of computer graphics and natural light sources. The optical unit may optionally be integrated with a view filtering device to filter the natural light images and reflect the two sources onto a single viewing surface. The view filtering device, such as a LCD panel or beam splitter, can receive signals from the computer image generator to display “black” blocks for features of the live exhibit that need to be removed. The computer image generator sends imagery to the monitor for each of these blocks that, when reflected, provide a replacement image. 
     Referring now to FIG. 10, another illustration of an optical unit  350  in accordance with an embodiment of the present invention will be described. The optical unit  350  may comprise a display based viewer that allows light to pass through it, as shown in FIG. 10, and that integrates computer generated images with natural light images directly at a display. The computer image generator sends VGA data to the display for only the pixels that represent the positions of overlay data. Because the display has no back light, it allows the complete live image to pass through to the viewer&#39;s eye, along with those pixels lit by the VGA signal. 
     Each of the optical unit configurations can optionally be integrated with FOV (Field of View) expansions, as shown in FIG. 11, or optical stereo devices, as shown in FIG.  12 . 
     As shown in FIG. 11, the FOV expansion system comprises FOV Compression Lenses  1110  stationed in front of each image source and FOV expansion lenses  1120  stationed in front of each eye port. The camera lens  1110  generates a wide-angle view of the exhibit and compresses it for optimal processing by the optics system. The image generation system provides overlay data with the same compression factors as the compression lens. Once the optic system generates the integrated view of live and computer images, the compressed data is displayed and then viewed through an expansion lens that makes the small and compressed display image appear as large as it was prior to compression. This maintains the magnitude scale for the viewer which is critical for creating the effect of viewing the overlaid exhibit to scale. 
     Referring now to FIG. 12, the optical stereo devices comprise simple LCD shutter  1210  systems that are placed in front of each eye port to control the presentation of right-and-left eye images generated from the computer animation device. In FIG. 12, a shutter system is used to create a 3-D effect. The optics system presents a right eye and left eye view that oscillate at over 30 Hz on the display. Lenses focus the display view to two shutters. The shutters oscillate at the same intervals and frequencies as the optics display to allow the right and left eyes to see the eye&#39;s perspective view, but not to see the other eye&#39;s perspective view. This same effect can be embodied in the device by using a separate monitor for each eye instead of lenses and shutters. 
     Referring now to FIG. 13, a flowchart illustrating a method  1300  for overlaying computer-generated images over a viewed image in accordance with an embodiment of the present invention will be described. The method  1300  begins at start step  1305  and proceeds to step  1310 . Preferably, the method proceeds to step  1310  when a user inserts a coin or token into a viewing device to begin the method  1300 . It should be understood that other methods of payment known to those skilled in the art may be alternatively used. 
     At step  1310 , the viewing device is initialized by determining the position of the viewing device relative to its initial orientation. After determining the position of the viewing device relative to its initial orientation, the method  1300  proceeds to step  1315 . 
     At step  1315 , a natural “through-the-lens” view of the exhibit site is provided to the user along with narration coinciding with the location that the user is viewing. The method then proceeds to step  1320 . 
     At step  1320 , information is provided to the user to guide the user to the proper viewing location at the exhibit site. For example, arrows may be provided on the viewing screen to direct the user to move the viewing device up, down, left or right depending on the viewing location that is to be described next in the narration. The method then proceeds to step  1325 . 
     At step  1325 , the viewing device recognizes the user&#39;s request for additional information regarding a location at the exhibit site. The user may activate a request for additional information by positioning the viewing device&#39;s center on the area of interest, and pushing a button on the image head. The method then proceeds to step  1330 . 
     At step  1330 , the viewing device generates a computer-generated animation related to the location at the exhibit site that the user is viewing through the viewing device and the method  1300  proceeds to step  1335 . 
     It should be understood that if the image head is moved after the overlaying has started, the following steps may occur. First, the movement of the image head in the azimuth and elevation direction is determined. Second, the new location of the image head is determined. Third, overlays for the imagery related to the new viewing location are created. Finally, the new computer-generated overlays are displayed over the live image. 
     At step  1335 , the computer-generated animation is overlaid onto the actual through-the-lens image viewed by the user. The method then ends at step  1399  when the timer expires and the viewing device shuts off. 
     From the foregoing description, it will be apparent to those skilled in the art that the present invention provides a method and apparatus for overlaying computer-generated animation onto an image viewed through a magnifying viewing device. 
     It should be understood that the viewing device  100  may have several different embodiments. For example, the power supply of the viewing device  100  may be either AC or DC compatible, as well as capable of supporting solar power generators. As another example, the casing for the image head  110  may be constructed from either metal or plastic, depending upon the environmental conditions expected to be encountered by the viewing device  100 . As still another example, the image head  110 , head mount  120 , stand  130 , and processing system  140  may be manufactured to be capable of withstanding severe environmental conditions to enable outdoor use. 
     Additionally, it should be understood that the viewing device  100  may be constructed in stationary or single degree-of-freedom configurations. These configurations would eliminate the head mount  120  (the image head  110  will mount directly on the stand  130 ), the position tracking system  330 , and the bearings  240  in the stand  130 . It should be further understood that the present invention may be configured without the audio option. 
     Other uses can also be made of the viewing device  100 . For instance, informational overlays can be generated to inform the user of how a volcano erupts, or how the Grand Canyon was formed. Other uses include labeling landmarks from overlooks, interactive gaming, construction and renovation planning, educational aids for product exhibits, numerous re-enactments, proposal of theories, and others. The uses of the present invention are virtually unlimited. 
     It will further be apparent to those skilled in the art that the present invention provides a method and apparatus for overlaying computer-generated animation onto an image viewed through a magnifying viewing device that is more cost-effective than human re-enactments and has greater availability to users, which would alleviate many congestion problems associated with human re-enactments. 
     It should still be further apparent that the present invention includes unique processing capabilities including the integration of navigational and inquiry processes to enable users to receive guided tours through an embedded overlay device. 
     While it is apparent that the invention herein disclosed is well calculated to fulfill the objects previously stated, it will be appreciated that numerous modifications and embodiments may be devised by those skilled in the art, and it is intended that the appended claims cover all such modifications and embodiments as fall within the true spirit and scope of the present invention. While the invention has been described with reference to details of the illustrated embodiments, these details are not intended to limit the scope of the present invention as particularly pointed out and distinctly claimed below.