US20010012011A1

US20010012011A1 - Camera-based interface to a virtual reality application

Info

Publication number: US20010012011A1
Application number: US08/829,107
Authority: US
Inventors: Mark Leavy
Original assignee: Intel Corp
Current assignee: Intel Corp
Priority date: 1997-03-31
Filing date: 1997-03-31
Publication date: 2001-08-09
Anticipated expiration: 2017-03-31
Also published as: US6407762B2

Abstract

A method and an apparatus for navigating and manipulating a virtual object in a virtual space using a digital camera as an input device are described. The method comprises the following steps. A plurality of video frames are received and analyzed by a video data analyzer to determine whether a predetermined set of data is present. The predetermined set of data includes several variables. First, whether a person is present in the video frame. Second, if a person is present, then whether the person's head is visible in the video frame. If the person's head is visible, then the position of the person's head in 3-D space is determined and recorded. Finally, the orientation of the person's head in 3-D space is also determined. The third variable is to determine whether a hand or hands are visible. If a hand is visible, the position of the hand in 3-D space is determined and recorded. The orientation of the hand in 3-D space is then determined and recorded. Finally, the state of the hand, whether it is open or closed, is determined and recorded. Information related to these three variables provides most of the information needed by a user to navigate through the virtual space and/or to manipulate a virtual object in the virtual space. The recognition of these three variables is obtained using well-known pattern recognition algorithms.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a virtual reality interface. More specifically, the present invention pertains to a method and apparatus for interacting with a virtual reality application.

2. Description of related art

Virtual reality has come to have many different definitions. One useful definition is “virtual reality is the delivery to a human of the most convincing illusion possible that they are in another reality.” D. Harrison & M. Jaques, Experiments in Virtual Reality, p. 2 (Butterworth-Heinemann, 1996). This virtual reality is located in digital electronic form in the memory of a computer. Thus, virtual reality is another way for humans to interact with a computer, for example, visually and/or by manipulating an object in the virtual space defined by the virtual reality.

Several methods currently exist that allow one to visualize, hear and/or navigate and/or manipulate objects in a virtual world or space. A virtual reality user has three main experiences in a virtual reality world: manipulation, navigation and immersion. Manipulation is defined as the ability to reach out, touch and move objects in the virtual world. Navigation is defined as the ability to move about and explore the virtual world. Id. at 8. Immersion is about completely enclosing the user so that the user perceives that he/she is actually in the virtual world.

Immersion is usually accomplished with the use of a head-mounted display (HMD) that provides all the visual input to the user, as well as audio and tactile input. HMDs suffer from several disadvantages. First, HMDs are cumbersome to use. Second, the HMD user can become motion sick.

Projected reality is another option to immersion. In projected (virtual) reality, the user sees him/herself projected into the action appearing on the screen. Projected reality uses several methods to interface between the user and the computer. For example, data gloves can be used for immersion as well as for projected reality. When the user wears the data glove, the user's hand movements are communicated to the computer so that the user can, for example, move his/her hand into the graphic representation of a virtual object and manipulate it.

Unfortunately, data gloves suffer from several disadvantages. First, there is often a delay between the user moving the data glove and then seeing the user's virtual hand movement on the display. Second, the electromechanical sensors on the data gloves often require constant recalibration. Third, affordable data gloves that accurately translate the user's hand movements into virtual hand movements in the virtual space are not currently available. Finally, data gloves and HMDs can be bothersome for a user to wear and to use.

A mouse is another interface that has been used to interact with a three-dimensional (3-D) display. Clicking on the mouse controls icons or graphical user interfaces that then control the movement of a virtual object. This is illustrated in FIG. 1A in which a prior art World

Wide Web browser

100 is shown. A three-dimensional virtual object 103 is displayed on a three-dimensional plane 105. Three graphical user interfaces, 109, 111 and 113 are used to control the movements of the virtual 3-D object 103 and the virtual 3-D circular plane 105. The virtual object 103 and virtual plane 105, however, move as a single unit. The user uses a mouse to click on graphical user interface 109 in order to move the virtual object 103 and the virtual plane 105 toward the user and/or away from the user. If the user wants to move virtual object 103 and virtual plane 105 up or down, then the user must click on and move graphical user interface 111 accordingly. The user clicks onto graphical user interface 113 in order to rotate the virtual object 103 and the virtual plane 105. The user is unable to simultaneously translate and rotate virtual object 103. Moreover, it is difficult for the user to translate the movements of the mouse in order to control

graphical user interfaces

109, 111 and 113. Thus, there is no direct linear correlation between the user's input at the mouse and the resulting motion on the graphical user interfaces 109-111 and 113, and the ultimate movement of virtual object 103 and virtual plane 105.

FIG. 1B shows what happens when the user has clicked on to

graphical user interface

113 to slightly rotate virtual object 103 and virtual plane. Instead virtual object 103 and virtual plane 105 are over-rotated so that they are partially off the display of the Web Browser 100. Thus, the user is unable to accurately predict and control the movement of 3-D virtual objects. In addition, the user is unable to simultaneously rotate and move virtual object 103 up and down, or towards and away from the user. Thus, the user cannot fully control any particular virtual object using the currently available input/output devices. Nor can the user achieve simultaneously a combination of more than two of the possible six degrees of freedom.

Three translations and three rotations are the six different degrees of freedom in which an object can move. An object can move forward or backward (X axis), up or down (Y axis) and left or right (Z axis). These three movements are collectively known as translations. In addition, objects can rotate about any of these principle axes. These three rotations are called roll (rotation about the X axis), yaw (rotation about the Y axis) and pitch (rotation about the Z axis).

Currently, a keyboard or a mouse are the most commonly available input devices that interact with certain 3-D virtual applications, such as three-dimensional Web browsers. The keyboard and mouse usually allow only horizontal and vertical movements. A keyboard and a mouse do not allow a user to navigate through a three-dimensional virtual space utilizing the six degrees of freedom. In addition, a keyboard and a mouse do not allow accurate manipulation of a virtual object. Thus, no input/output device exists for accurately mapping a user's six degrees of freedom of movement into a 3-D virtual reality application.

Therefore, it is desirable to have an affordable non-invasive interface between a user and a virtual space that allows the user to manipulate objects and to navigate through the virtual space with six degrees of freedom in a nonsequential manner.

SUMMARY

A computer-implemented method for operating in a virtual space is described. The method comprises the following steps. A visual detection device is used to determine whether a predetermined set of data exists in user movement data. It is determined if the predetermined set of data has changed. The changed predetermined set of data is provided to a virtual reality application program that is generating the virtual space. The predetermined set of data is used by the virtual reality application program to perform an action in the virtual space.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not a limitation in the figures of the accompanying drawings in which like references indicate similar elements. [0015]
FIG. 1A illustrates a prior art Web browser. [0016]
FIG. 1B illustrates the prior art Web browser of FIG. 1A after a virtual object has been rotated. [0017]
FIG. 2 illustrates an exemplary computer system in which the present invention may be implemented. [0018]
FIG. 2A illustrates the components of main memory in one embodiment. [0019]
FIG. 3 illustrates a flow chart utilizing an embodiment of the present invention. [0020]
FIG. 4A illustrates another embodiment of the present invention in part of a flow chart. [0021]
FIG. 4B is a continuation of the flow chart in FIG. 4A. [0022]
FIG. 5 is a flow chart illustrating yet another embodiment of the present invention. [0023]

DETAILED DESCRIPTION

A method and an apparatus for interacting with a virtual reality application are described. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known structures, processes and devices are shown in block diagram form in order to avoid unnecessarily obscuring the present invention. [0024]
The present invention uses a digital camera as an input device. The input received from the digital camera is analyzed, and the analysis' results are then used to interact directly with a virtual reality application program on a computer system. [0025]
The present invention provides several advantages over the prior art. First, the use of the digital camera provides greater accuracy in projecting the user's actual movement into virtual movement within a virtual space generated by the virtual reality application. For example, if a user wants to move a virtual object displayed in the virtual space, the user moves his/her hand in the camera's view so that the user's movements are recognized and used to manipulate the virtual object. Second, the use of the digital camera allows the user to use all six degrees of freedom in manipulating a virtual object or in navigating through the virtual space. The user is freed from the limitations presented by a mouse or a keyboard. As a result, unlike the prior art Web browser of FIG. 1A, a user can simultaneously rotate and move the [0026] virtual object 103 toward the user or any other possible combination of movements. Third, an inexpensive digital camera that is often bundled with the computer system may be used. Fourth, there is no longer the use of an intrusive and uncomfortable interface, such as a head mounted display or a data glove, between the user and the virtual reality application. Instead, the digital camera is a non-invasive input device that does not create any of the problems associated with, for example, a head mounted display, such as motion sickness.
FIG. 2 illustrates an [0027] exemplary computer system 200 in which the present invention operates. Exemplary computer system 200, which is illustrated in FIG. 2, comprises a bus 202 for communicating information, and a processor 204 coupled with bus 202 for processing information. A main memory 208 is coupled with bus 202 for storing information and instructions for the processor 204. A display device 214 is coupled to bus 202 for displaying information for a computer user. An input device 217, such as mouse or keyboard, can be coupled to the bus 202 for communicating information and command selections to the processor 204 and a mass storage device 212.
A [0028] digital camera 216 that operates like an input device is advantageously included and coupled to the bus 202 for facilitating communication of information and command selections to the processor 202. See, e.g., J. Segen and S. Pingali, “A Camera-Based System For Tracking People in Real Time,” pp. 63-67, 13th International Conference on Pattern Recognition (Aug. 25-29, 1996). In a preferred embodiment, a COMPAQ™ digital camera is used that is manufactured by COMPAQ™ Corporation of Houston, Tex. A video capture device 205 receives video data from digital camera 216 and then transmits the video data to video RAM (random access memory) 207. VRAM 207 transmits the video data to display device 214 and to bus 202, which then transmits the video data to main memory 208.
[0029] Processor 204 may be any of a wide variety of general purpose processors or microprocessors, such as the Pentium™ microprocessor manufactured by Intel™ Corporation of Santa Clara, Calif. It will be apparent to those of ordinary skill in the art, however, that other types of processors may also be used. Display device 214 may be a liquid crystal device, a cathode ray tube (CRT) or any other suitable display device. A mass storage device 212, such as a magnetic disk and associated disk drive, is also coupled to the bus 202 for storing information and instructions. Mass storage device 212 may be a conventional hard disk drive, a floppy disk drive, a CD-ROM drive, or other magnetic or optical data storage device for reading and writing information stored on a hard disk, a floppy disk, a CD-ROM, a magnetic disk, or other magnetic or optical data storage medium.
Referring to FIG. 2A, main memory, in one embodiment, comprises a [0030] video data analyzer 220, a virtual reality program 222 and pattern recognition software 224, which is well-known in the art. See, e.g., J. L. Crowley et al., “Vision for Man Machine Interaction,” European Computer Vision Network (1993). Video data analyzer 220 receives video data 218 from VRAM 207 via bus 202. Video data analyzer 220 analyzes the incoming video data to determine whether a predetermined set of data is present. If it is present, then video data analyzer 220 transmits the predetermined set of data to virtual reality program 222. Moreover, video data analyzer 220 determines if there are any changes in the predetermined set of data and transmits any changes to virtual reality program 222. In addition, video data analyzer 220 also transmits video data 218 to pattern recognition software unit 224.
Although the present invention has been described above utilizing a single computer system, it will be apparent to one of skill in the art that the present invention may also be implemented on more than one computer system. For example, a first computer system could receive the input from the digital camera, analyze the input and then extract only the relevant information, such as a predetermined set of data. The relevant information is then output from the first computer system and fed as input into a second computer system, which contains the virtual reality application. [0031]
Referring to FIG. 3, a flow chart of one embodiment of the present invention is illustrated. In [0032] step 300, the video data analyzer 220 receives input from the digital camera and then analyzes each of the video frames. A digital camera typically produces about 30 frames per second. In particular, in step 302, the video data analyzer 220 analyzes the video frames to determine if a predetermined set of data is present. The predetermined set of data may be specified by the user or preselected by software. The analysis of whether a predetermined set of data is present is made by well-known pattern recognition algorithms. If the predetermined set of data is present then the predetermined set of data is extracted in step 304. This extraction process helps avoid overloading the virtual application program 222 with redundant or useless data.
In [0033] step 306, the video data analyzer 220 is sampling the video frames to determine if there is any change in the predetermined set of data from a set of initial values for the predetermined set of data. For example, if the predetermined set of data initially stated that a person is present in a video frame, a change could mean that the person is no longer in the video frame, or that the person's position in the video frame has changed. If there is any change in the predetermined set of data, the computer will return to step 304 and extract the modified predetermined set of data. In step 308, the predetermined set of data (which is defined to include an initial value and any changes to the initial value) is sent to the desired application, such as a virtual reality application program. During this process, the video data analyzer 220 continues to receive and analyze each of the video frames captured by the digital camera.
FIGS. [0034] 4A-B illustrate a flow chart for the extraction of the predetermined set of data by video data analyzer 220, in one embodiment of the present invention. Referring to FIG. 4A, in decision diamond 400, the digital camera may be receiving input. If the digital camera is receiving data, then the next step is decision diamond 402. The first variable of the predetermined set of data is whether a person is present in a video frame as shown in decision diamond 402. The recognition of a person by a computer system using pattern recognition software is well-known in the art. See e.g., Ashok Samal and Prasana A. Iyengar, “Automatic Recognition and Analysis of Human Faces and Facial Expressions: A Survey,” Pattern Recognition, Vol. 25, No. 1, pp. 65-77, 1992. If a person is not present, then the video data input is discarded in step 401 and step 400 is repeated. If a person is present, then the video data analyzer 220 may choose to go along two different paths in parallel (as shown) or asynchronously (not shown). Since both paths cannot be discussed simultaneously, the path on the flow chart (i.e., beginning with step 404) will be discussed first.
In [0035] step 404, using conventional pattern recognition techniques, the video data analyzer 220 determines if there is a head visible in the video frame. See, e.g., R. Foltyniewicz, “Automatic Face Recognition via Wavelets and Mathematical Morphology,” pp. 13-17, 13th International Conference on Pattern Recognition (Aug. 25-29, 1996). If the answer is no, then the next step is synchronization (“Sync”) with the pathway that begins with step 414. But if the answer is yes, then in step 406, the position of the head in 3-D space is determined. In step 408, the position of the head is recorded so that it can be used to map its position to a corresponding position within the virtual reality application. In step 410, the orientation of the head in three-dimensional space is recorded. For example, the orientation describes whether the front of the head is facing the camera or whether the head is turned to one side. The orientation of the head in three-dimensional space can reflect the perspective seen by the user and thus, the perspective shown on the display. Referring to FIG. 4B, in step 412, the orientation of the head is recorded.
Since the person in front of the digital camera can navigate through the virtual space shown on the display, the person can move around, which means the person's head can also move. As a result, in [0036] step 413, whether the position and/or orientation of the head has changed is (are) determined. If the position of the person's head is changed, then the new position of the head is provided to the virtual reality application in step 415. In addition, if the orientation of the head has changed, then that new orientation is also provided to the virtual reality application in step 415. The next step is synchronization.
In [0037] step 414 of FIG. 4A, whether a hand is visible is determined using well-known pattern recognition algorithms. If no hand is visible in a video frame, then the next step is synchronization. But if a hand is visible, in step 416, the position of the hand (or hands) in 3-D space is determined. The position of the hand is recorded in step 418. The position of the hand is then correlated (or mapped) to a position for the hand in the virtual space generated by the virtual reality application. In step 420, the orientation of the hand in 3-D space is determined. The orientation of the hand is recorded in step 422 of FIG. 4B. The next step is to determine whether the hand is opened or closed (i.e., the state of the hand) in step 424. If the hand appears more planar than spherical, then the hand is determined to be open. If the shape of the hand is determined to be more spherical than planar, then the hand is determined to be closed. But if the hand is between open and closed then a “maximum likelihood” estimation is made to choose the closest state. All of this is determined by using pattern recognition software that is well-known in the art.
If the hand is open, then the hand is available to grasp or manipulate a virtual object created by the virtual reality application. Unlike the prior art, there is not an additional barrier or interface between the virtual object and the user's projected ability to manipulate the virtual object. See, e.g., G. W. Fitzmaurice et al., “Bricks: Laying the Foundations for Graspable User Interfaces,” CHI '95 Proceedings Papers. In [0038] step 426, the state of the hand, whether it is opened or closed, is recorded. In step 428, whether another hand is visible is determined. If another hand is visible, then steps 416 through 428 are repeated. But if another hand is not visible, then the next question is whether the position and/or orientation and/or state of the hand has changed in step 429. If there are any changes, for example, if the position of the hand (whether it is the first hand noted or the second hand observed) has changed, then the changes are provided to the virtual reality application program in step 430.
The [0039] video data analyzer 220 is constantly updating the angle of a hand and the vectors describing the hand each time the hand moves. This is important because the present invention allows a hand to move non-sequentially with six degrees of freedom of movement in the virtual space. A projection of the hand can move into the virtual reality application, unhindered by previous input devices, such as a mouse or a keyboard. It will be appreciated that the present invention can be used to sequentially recognize and process one hand's movements at a time or it can recognize and process almost simultaneously the movements of more than one hand.
FIG. 5 illustrates a flow chart for one embodiment of a pattern recognition algorithm that may be used in the present invention. In [0040] step 500, the computer initializes the position of a pattern or a template using conventional pattern recognition algorithms. This pattern may be for a person, a head and/or a hand or hands. The extraction of a predetermined set of data that includes information about these three variables—a person's presence, head and hand(s)—provides most of the information needed for a person to interact with a virtual reality application program. For example, the digital camera may provide a video frame in which a head is located at a (X, Y, Z) position. In step 503, that image (or a bitmap of that image) of the head is loaded into the computer's memory. In step 505, pattern recognition for a face and/or hands is implemented, in one embodiment, in order to identify the received image.
In [0041] step 507, if there was a previous frame with an identifiable pattern, then the recognized pattern in the previous frame is compared to the current frame. This is to determine if there are any changes in the video frame. In step 509, it is determined if there is any relative movement of the recognized pattern. For example, has the person's head and/or hands moved since the previous video frame. If any change is detected in the predetermined set of data (e.g., hand moved), then a modified set of data is created. This modified set of data can be used to perform an action, such as manipulate a first or a second virtual object. The second virtual object may be the first virtual object in a different position, or an entirely different object than the first virtual object. In step 511, the relative movement of the person's head and/or hands is then fed as input to a virtual reality application program. It is to be appreciated that this virtual reality application can be a 3-D Web page or 3-D Web Browser. Steps 503-511 are repeated as a continuous loop while the video data analyzer is receiving and processing images from the digital camera.
It will be apparent to one of skill in the art that the present invention can be used to record the actions of more than one person or any other living subject. Thus, the present invention may be used to record the movements of a group of people, who may then simultaneously interact with a virtual reality application, such as a virtual game. For example, if the game required the participants to raise their hands every time someone knew the answer to a question, the digital camera can record the first person who raised his or her hand in response to the question. In other words, unlike prior art systems, more than one individual can interact with a virtual reality program using one embodiment of the present invention. A group of individuals, within the digital camera's view, can interact as a group with a virtual reality program. Thus, the present invention can make the use of virtual reality programs less of a solitary experience. [0042]
It will also be appreciated that the present invention can be used to track and record variables other than the ones described. [0043]
The foregoing description provides an example of a method and an apparatus for using a digital camera as an input device for a computer system running a virtual reality application. The use of a digital camera as an input device is meant to be illustrative and not limiting. [Mark-can you think of anything else that can be used as an input device?] It will be appreciated that numerous modifications may be made in practicing the present invention without departing from the spirit and scope of the invention, which is defined by the following claims. [0044]

Claims

We claim:

1. A computer-implemented method for operating in a virtual space, comprising the steps of:

determining whether a predetermined set of data exists in user movement data received from a visual detection device;

determining if the predetermined set of data has changed;

providing the changed predetermined set of data to a virtual reality application program that is generating the virtual space; and

using the changed predetermined set of data, wherein the virtual reality application program uses the changed predetermined set of data to perform an action in the virtual space.

2. The computer-implemented method of

claim 1

, wherein the action is manipulating a first virtual object displayed on a display device of the computer system.

3. The computer-implemented method of

claim 1

, wherein the action is navigating through the virtual space.

4. The computer-implemented method of

claim 1

, wherein the predetermined set of data includes whether a person is detected by the visual detection device.

5. The computer-implemented method of

claim 1

, wherein the predetermined set of data includes whether a human head is present.

6. The computer-implemented method of

claim 5

, wherein if the human head is present, the predetermined set of data further includes a position of the head and an orientation of the head in three-dimensional space.

7. The computer-implemented method of

claim 1

, wherein the predetermined set of data includes whether a human hand is present.

8. The computer-implemented method of

claim 7

, wherein if the hand is present, the predetermined set of data further includes a position of the hand and an orientation of the hand in three-dimensional space, and whether the hand is open or closed.

9. The computer-implemented method of

claim 7

, wherein the step of determining whether a predetermined set of data exists includes determining that if the hand is shaped more like a plane than a sphere, then the hand is open.

10. The computer-implemented method of

claim 7

, wherein the step of determining that whether a predetermined set of data exists includes determining that if the hand is shaped more like a sphere than a flat plane, then the hand is closed.

11. The computer-implemented method of

claim 1

, wherein the visual detection device is a digital camera.

12. The computer-implemented method of

claim 1

, further including the step of:

mapping the predetermined set of data to the virtual space created by the virtual reality application on a computer system.

13. The method of

claim 2

, further including the step of:

detecting any changes in the predetermined set of data to create a modified predetermined set of data; and

using the modified predetermined set of data to manipulate a second virtual object displayed on a display device of the computer system.

14. The method of

claim 13

, wherein the first virtual object is manipulated through six degrees of freedom.

15. The method of

claim 13

, wherein the second virtual object is manipulated through six degrees of freedom.

16. The method of

claim 15

, wherein the first virtual object and the second virtual object are different virtual objects.

17. The method of

claim 15

, wherein the first virtual object and the second virtual object are the same virtual object, wherein the second virtual object is a modified first virtual object.

18. A method of operating in a virtual space using a digital camera as an input device, wherein the digital camera is coupled to a computer system having a display device on which the virtual space is displayed, the method comprising the steps of:

using the digital camera to capture video data;

analyzing the video data to determine if a predetermined set of video data is present;

generating analysis results based on an analysis of the video data;

transmitting the analysis results of the predetermined set of video data to a virtual reality program running on the computer system, wherein the virtual reality program generates the virtual space;

displaying a virtual object on the display device, wherein the virtual object is a part of the virtual space; and

using the analysis results of the predetermined set of video data to interact within the virtual space.

19. The method of

claim 18

, further including the step of:

navigating through the virtual space in six degrees of freedom using the analysis results of the predetermined set of video data.

20. The method of

claim 18

, further including the step of:

manipulating the virtual object in six degrees of freedom using the analysis results of the predetermined set of video data.

21. The method of

claim 18

, further including the steps of:

analyzing the video data to determine if a variable of the predetermined set of video data has been modified; and

transmitting a modified variable to the virtual reality program.

22. The method of

claim 21

, further including the step of:

using the modified variable to interact with the virtual object.

23. The method of

claim 22

, wherein interacting with the virtual object includes manipulating the virtual object.

24. The method of

claim 21

, further including the step of:

using the modified variable to navigate through the virtual space.

25. The method of

claim 18

, wherein the predetermined set of video data includes video data for determining whether a person is present.

26. The method of

claim 18

, wherein the predetermined set of video data includes video data for determining whether a human head is present, and if present, what is a position of the human head and an orientation of the human head in three-dimensional space.

27. The method of

claim 18

, wherein the predetermined set of data includes video data for determining whether a human hand is present, and if present, what is a position of the human hand, an orientation of the human hand in three-dimensional space, and whether the human hand is open or closed.

28. The method of

claim 22

, wherein the modified variable includes changes in a position, an orientation and a state of a hand.

29. The method of

claim 22

, wherein the modified variable includes changes in a position and an orientation of a human head.

30. The method of

claim 21

,

wherein the predetermined set of video data also includes video data for determining whether a person is present;

wherein the predetermined set of video data further includes video data for determining whether a human head is present, and if present, a position of the human head and an orientation of the human head in three-dimensional space;

wherein the predetermined set of data also includes video data for determining whether a human hand is present, and if present, a position of the human hand, an orientation of the human hand in three-dimensional space and whether the human hand is open or closed;

wherein the modified variable includes changes in a position, an orientation and a state of a hand; and

wherein the modified variable further includes changes in a position and an orientation of a human head.

31. A computer system, comprising:

a first bus;

a memory coupled to the first bus and the processor, wherein the memory includes a virtual reality application and a video data analyzer;

a network interface coupled to the first bus;

a video capture device coupled to the first bus; and

a digital camera coupled to the video data capture device, wherein the input to the digital camera is capable of being used by the video data analyzer to interact with a virtual space generated by the virtual reality application.

32. The computer system of

claim 31

, wherein the input from the digital camera is used by the virtual reality application to manipulate a virtual object in the virtual space.

33. The computer system of

claim 31

, wherein the input from the digital camera is used by the virtual reality application to navigate through the virtual space.

34. The computer system of

claim 31

, wherein the video data analyzer performs the following steps:

receiving input from the digital camera;

analyzing the input to determine if a predetermined set of data is present;

generating analysis results based on an analysis of the predetermined set of data;

transmitting the analysis results to the virtual reality application; and

using the analysis results to interact with a virtual space generated by the virtual reality application.

35. The computer system of

claim 34

, wherein the video data analyzer further performs the following step:

navigating through the virtual space in six degrees of freedom using the analysis results.

36. The computer system of

claim 34

, wherein the video data analyzer further performs the following step:

manipulating a virtual object in the virtual space in six degrees of freedom using the analysis results.