Patent Description:
Games are played by wearing a head-mounted display, connected to a game console, on the head, watching a screen displayed on the head-mounted display, and manipulating a controller or other device. With an ordinary stationary display, a user's field-of-view range spreads outside the display screen, possibly making it impossible to focus one's attention on the display screen or resulting in insufficient sense of immersion. In that respect, when a head-mounted display is worn, a user cannot see anything other than an image appearing on the head-mounted display, thereby increasing a sense of immersion into the image world and further enhancing the entertaining nature of the game. Previously proposed arrangements are disclosed in <CIT>, <CIT>, and <CIT>.

The inventor recognized the need for a more convenient display control technology to ensure that games using a head-mounted display can be enjoyed by more user segments.

In order to solve the above problem, a display control apparatus according to a mode of the present invention includes a display control section that generates a virtual space image by specifying a viewpoint position and a direction of line of sight and displays the image on a head-mounted display.

It should be noted that arbitrary combinations of the above components and conversions of expressions of the present invention between method, apparatus, system, program, and so on are also effective as modes of the present invention.

According to the present invention, it is possible to improve convenience of head-mounted display users.

In the present embodiment, a description will be given of a display technology using a head-mounted display (HMD). A head-mounted display is a display apparatus worn on a user's head in such a manner as to cover his or her eyes so that the user can view still images and videos appearing on a display screen provided in front of user's eyes. What appears on the head-mounted display may be content such as movies and television (TV) programs. In the present embodiment, however, a description will be given of an example in which a head-mounted display is used as a display apparatus for displaying game images.

<FIG> is a diagram illustrating an environment in which a game system <NUM> according to an embodiment is used. The game system <NUM> includes a gaming apparatus <NUM>, an input apparatus <NUM>, an imaging apparatus <NUM>, a head-mounted display <NUM>, and a display apparatus <NUM>. The gaming apparatus <NUM> executes a game program. The input apparatus <NUM> is used to input a user instruction to the gaming apparatus <NUM>. The imaging apparatus <NUM> images a real space around a user. The head-mounted display <NUM> displays a first game image generated by the gaming apparatus <NUM>. The display apparatus <NUM> displays a second game image generated by the gaming apparatus <NUM>.

The gaming apparatus <NUM> executes a game program based on an instruction input supplied from the input apparatus <NUM> or the head-mounted display <NUM>, a position or attitude of the input apparatus <NUM> or the head-mounted display <NUM>, and so on, generates a first game image and transports the image to the head-mounted display <NUM>, and generates a second game image and transports the image to the display apparatus <NUM>.

The head-mounted display <NUM> displays the first game image generated by the gaming apparatus <NUM>. The head-mounted display <NUM> also transports, to the gaming apparatus <NUM>, information related to user input to the input apparatus provided on the head-mounted display <NUM>. The head-mounted display <NUM> may be connected to the gaming apparatus <NUM> with a wired cable. Alternatively, the head-mounted display <NUM> may be connected wirelessly through wireless local area network (LAN) or other means.

The display apparatus <NUM> displays a second game image generated by the gaming apparatus <NUM>. The display apparatus <NUM> may be a TV having a display and a speaker. Alternatively, the display apparatus <NUM> may be a computer display or other apparatus.

The input apparatus <NUM> has a function to transport user instruction input to the gaming apparatus <NUM> and is configured as a wireless controller capable of wirelessly communicating with the gaming apparatus <NUM> in the present embodiment. The input apparatus <NUM> and the gaming apparatus <NUM> may establish wireless connection using Bluetooth (registered trademark) protocol. It should be noted that the input apparatus <NUM> is not limited to a wireless controller and may be a wired controller connected to the gaming apparatus <NUM> via a cable.

The input apparatus <NUM> is driven by batteries and is configured to have a plurality of buttons for making instruction input so as to progress the game. When the user operates a button on the input apparatus <NUM>, instruction input resulting from the operation is sent to the gaming apparatus <NUM> through wireless communication.

The imaging apparatus <NUM> is a video camera that includes, for example, a charge-coupled device (CCD) imaging device or a complementary metal-oxide semiconductor (CMOS) imaging device and generates, by imaging a real space at a given interval, a frame image for each interval. The imaging apparatus <NUM> is connected to the gaming apparatus <NUM> via a universal serial bus (USB) or other interface. An image captured by the imaging apparatus <NUM> is used by the gaming apparatus <NUM> to derive the positions and attitudes of the input apparatus <NUM> and the head-mounted display <NUM>. The imaging apparatus <NUM> may be a ranging camera or a stereo camera capable of acquiring a distance. In this case, the imaging apparatus <NUM> makes it possible to acquire the distance between the imaging apparatus <NUM> and the input apparatus <NUM> or the head-mounted display <NUM>.

In the game system <NUM> of the present embodiment, the input apparatus <NUM> and the head-mounted display <NUM> have a light-emitting section configured to emit light in a plurality of colors. During a game, the light-emitting section emits light in the color specified by the gaming apparatus <NUM> and is imaged by the imaging apparatus <NUM>. The imaging apparatus <NUM> images the input apparatus <NUM>, generates a frame image, and supplies the image to the gaming apparatus <NUM>. The gaming apparatus <NUM> acquires the frame image and derives position information of the light-emitting section in the real space from the position and size of the image of the light-emitting section in the frame image. The gaming apparatus <NUM> treats position information as a game operation instruction and reflects position information in game processing including controlling the action of a player's character.

Also, the input apparatus <NUM> and the head-mounted display <NUM> have an acceleration sensor and a gyrosensor. Sensor detection values are sent to the gaming apparatus <NUM> at a given interval, and the gaming apparatus <NUM> acquires sensor detection values and acquires attitude information of the input apparatus <NUM> and the head-mounted display <NUM> in the real space. The gaming apparatus <NUM> treats attitude information as a game operation instruction and reflects attitude information in game processing.

<FIG> is an external view of the head-mounted display <NUM> according to the embodiment. The head-mounted display <NUM> includes a main body section <NUM>, a head contact section <NUM>, and a light-emitting section <NUM>.

The main body section <NUM> includes a display, a global positioning system (GPS) unit for acquiring position information, an attitude sensor, a communication apparatus, and so on. The head contact section <NUM> may include a biological information acquisition sensor capable of measuring user's biological information such as temperature, pulse, blood components, perspiration, brain waves, and cerebral blood flow. As described above, the light-emitting section <NUM> emits light in the color specified by the gaming apparatus <NUM> and functions as a criterion for calculating the position of the head-mounted display <NUM> in the image captured by the imaging apparatus <NUM>.

A camera for capturing the user's eyes may be further provided on the head-mounted display <NUM>. The camera mounted to the head-mounted display <NUM> permits detection of the user's line of sight, movement of the pupils, blinking, and so on.

Although a description will be given of the head-mounted display <NUM> in the present embodiment, the display control technology of the present embodiment is applicable not only to a case in which the head-mounted display <NUM> in a narrow sense is worn but also to a case in which eyeglasses, an eyeglass-type display, an eyeglass-type camera, a headphone, a headset (microphone equipped headphone), an earphone, an earring, an ear-mounted camera, a hat, a camera-equipped hat, or hair band is worn.

<FIG> is a functional configuration diagram of the head-mounted display <NUM>. The head-mounted display <NUM> includes an input interface <NUM>, an output interface <NUM>, a backlight <NUM>, a communication control section <NUM>, a network adapter <NUM>, an antenna <NUM>, a storage section <NUM>, a GPS unit <NUM>, a wireless unit <NUM>, an attitude sensor <NUM>, an external input/output (I/O) terminal interface <NUM>, an external memory <NUM>, a clock section <NUM>, a display apparatus <NUM>, and a control section <NUM>. These functional blocks can also be realized by hardware alone, software alone, or a combination thereof in various forms.

The control section <NUM> is a main processor that processes and outputs signals such as image signals and sensor signals, instructions, and data. The input interface <NUM> accepts an operation signal and a setup signal from input buttons and so on and supplies these signals to the control section <NUM>. The output interface <NUM> receives an image signal from the control section <NUM> and displays the signal on the display apparatus <NUM>. The backlight <NUM> supplies backlight to a liquid crystal display making up the display apparatus <NUM>.

The communication control section <NUM> sends, to external equipment, data input from the control section <NUM> in a wired or wireless communication manner via the network adapter <NUM> or the antenna <NUM>. The communication control section <NUM> receives data from external equipment in a wired or wireless manner via the network adapter <NUM> or the antenna <NUM> and outputs the data to the control section <NUM>.

The storage section <NUM> temporarily stores data and parameters processed by the control section <NUM>, operation signals, and so on.

The GPS unit <NUM> receives position information from a GPS satellite in accordance with an operation signal from the control section <NUM> and supplies position information to the control section <NUM>. The wireless unit <NUM> receives position information from a wireless base station in accordance with an operation signal from the control section <NUM> and supplies position information to the control section <NUM>.

The attitude sensor <NUM> detects attitude information such as orientation and tilt of the main body section <NUM> of the head-mounted display <NUM>. The attitude sensor <NUM> is realized by combining a gyrosensor, an acceleration sensor, an angular acceleration sensor, and so on as appropriate.

The external I/O terminal interface <NUM> is an interface for connecting peripheral equipment such as USB controller. The external memory <NUM> is an external memory such as flash memory.

The clock section <NUM> specifies time information using a setup signal from the control section <NUM> and supplies time information to the control section <NUM>.

<FIG> illustrates an external configuration of the input apparatus <NUM>, and <FIG> illustrates a top surface configuration of the input apparatus <NUM>, and <FIG> illustrates a bottom surface configuration of the input apparatus <NUM>. The input apparatus <NUM> has a light-emitting body <NUM> and a handle <NUM>. The light-emitting body <NUM> has an outside light-emitting device made of a light-transmitting resin formed in a spherical shape and a light-emitting diode or an electric bulb therein. When the light-emitting device therein emits light, the entire outside spherical body shines. Operating buttons <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are provided on the top surface of the handle <NUM>, and an operating button <NUM> is provided on the bottom surface thereof. The user operates the operating buttons <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> with the thumb and the operating button <NUM> with the index finger while holding an end portion of the handle <NUM> with the hand. The operating buttons <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> include pushbuttons and are operated as the user presses them. The operating button <NUM> may be a button that permits entry of an analog amount.

The user plays a game while watching a game screen displayed on the display apparatus <NUM>. The imaging apparatus <NUM> needs to image the light-emitting body <NUM> during execution of a game application. Therefore, an imaging range thereof is preferably arranged to face the same direction as the display apparatus <NUM>. In general, the user often plays games in front of the display apparatus <NUM>. Therefore, the imaging apparatus <NUM> is arranged such that an optical axis thereof matches a front direction of the display apparatus <NUM>. Specifically, the imaging apparatus <NUM> is preferably arranged near the display apparatus <NUM> such that the imaging range thereof includes a position where the user can visually recognize the display screen of the display apparatus <NUM>. This allows the imaging apparatus <NUM> to image the input apparatus <NUM>.

<FIG> illustrates an internal configuration of the input apparatus <NUM>. The input apparatus <NUM> includes a wireless communication module <NUM>, a processing section <NUM>, a light-emitting section <NUM>, and the operating buttons <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. The wireless communication module <NUM> has a function to send and receive data to and from a wireless communication module of the gaming apparatus <NUM>. The processing section <NUM> performs predetermined processes in the input apparatus <NUM>.

The processing section <NUM> includes a main control section <NUM>, an input acceptance section <NUM>, a triaxial acceleration sensor <NUM>, a triaxial gyrosensor <NUM>, and a light emission control section <NUM>. The main control section <NUM> sends and receives necessary data to and from the wireless communication module <NUM>.

The input acceptance section <NUM> accepts input information from the operating buttons <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> and sends input information to the main control section <NUM>. The triaxial acceleration sensor <NUM> detects acceleration components of three axial directions of X, Y, and Z. The triaxial gyrosensor <NUM> detects angular speeds on XZ, ZY, and YX planes. It should be noted that, here, width, height, and length directions of the input apparatus <NUM> are specified as X, Y, and Z axes. The triaxial acceleration sensor <NUM> and the triaxial gyrosensor <NUM> are preferably arranged inside the handle <NUM> and near the center inside the handle <NUM>. The wireless communication module <NUM> sends, together with input information from the operating buttons, detection value information obtained by the triaxial acceleration sensor <NUM> and detection value information obtained by the triaxial gyrosensor <NUM>, to the wireless communication module of the gaming apparatus <NUM> at a given interval. This transmission interval is set, for example, at <NUM> milliseconds.

The light emission control section <NUM> controls light emission of the light-emitting section <NUM>. The light-emitting section <NUM> has a red light-emitting diode (LED) 64a, a green LED 64b, and a blue LED 64c, thereby allowing them to emit light in a plurality of colors. The light emission control section <NUM> causes the light-emitting section <NUM> to emit light in a desired color by controlling light emission of the red LED 64a, the green LED 64b, and the blue LED 64c.

When a light emission instruction is received from the gaming apparatus <NUM>, the wireless communication module <NUM> supplies the light emission instruction to the main control section <NUM>. The main control section <NUM> supplies the light emission instruction to the light emission control section <NUM>. The light emission control section <NUM> controls light emission of the red LED 64a, the green LED 64b, and the blue LED 64c such that the light-emitting section <NUM> emits light in the color specified by the light emission instruction. For example, the light emission control section <NUM> may control lighting of each LED through pulse width modulation (PWM) control.

<FIG> illustrates a configuration of the gaming apparatus <NUM>. The gaming apparatus <NUM> includes a frame image acquisition section <NUM>, an image processing section <NUM>, a device information deriving section <NUM>, a wireless communication module <NUM>, an input acceptance section <NUM>, an output section <NUM>, and an application processing section <NUM>. The processing capability of the gaming apparatus <NUM> in the present embodiment is realized by a central processing unit (CPU), a memory, and a program loaded into the memory, and so on. Here, a configuration is depicted that is realized by these components working with each other in a coordinated fashion. The program may be built into the gaming apparatus <NUM>. Alternatively, the program may be externally supplied stored in a recording medium. Therefore, it is to be understood by those skilled in the art that these functional blocks can be realized in various ways by hardware alone, software alone, or a combination thereof. It should be noted that the gaming apparatus <NUM> may have a plurality of CPUs from a viewpoint of hardware configuration.

The wireless communication module <NUM> establishes wireless communication with the wireless communication module <NUM> of the input apparatus <NUM>. This allows the input apparatus <NUM> to send operating button state information and detection value information of the triaxial acceleration sensor <NUM> and the triaxial gyrosensor <NUM> to the gaming apparatus <NUM> at a given interval.

The wireless communication module <NUM> receives operating button state information and sensor detection value information sent from the input apparatus <NUM> and supplies them to the input acceptance section <NUM>. The input acceptance section <NUM> separates button state information and sensor detection value information and hands them over to the application processing section <NUM>. The application processing section <NUM> receives button state information and sensor detection value information as a game operation instruction. The application processing section <NUM> treats sensor detection value information as attitude information of the input apparatus <NUM>.

The frame image acquisition section <NUM> is configured as a USB interface and acquires frame images at a given imaging speed (e.g., <NUM> frames/second) from the imaging apparatus <NUM>. The image processing section <NUM> extracts a light-emitting body image from a frame image. The image processing section <NUM> identifies the position and size of the light-emitting body in the frame images. For example, as the light-emitting body <NUM> of the input apparatus <NUM> emits light in a color that is unlikely used in the user's environment, the image processing section <NUM> can extract a light-emitting body image from a frame image with high accuracy. The image processing section <NUM> may generate a binarized image by binarizing frame image data using a given threshold. This binarization encodes a pixel value of a pixel having luminance higher than the given threshold as "<NUM>" and the pixel value of a pixel having luminance equal to or lower than the given threshold as "<NUM>. " By causing the light-emitting body <NUM> to light up at luminance beyond this given threshold, the image processing section <NUM> can identify the position and size of the light-emitting body image from the binarized image. For example, the image processing section <NUM> identifies coordinates of a center of gravity and a radius of the light-emitting body image in the frame image.

The device information deriving section <NUM> derives position information of the input apparatus <NUM> and the head-mounted display <NUM> as seen from the imaging apparatus <NUM> from the position and size of the light-emitting body image identified by the image processing section <NUM>. The device information deriving section <NUM> derives position coordinates in camera coordinates from the center of gravity of the light-emitting body image and also derives distance information from the imaging apparatus <NUM> from the radius of the light-emitting body image. The position coordinates and the distance information make up position information of the input apparatus <NUM> and the head-mounted display <NUM>. The device information deriving section <NUM> derives position information of the input apparatus <NUM> and the head-mounted display <NUM> for each frame image and hands over position information to the application processing section <NUM>. The application processing section <NUM> receives position information of the input apparatus <NUM> and the head-mounted display <NUM> as a game operation instruction.

The application processing section <NUM> progresses the game from position information and attitude information of the input apparatus <NUM> and button state information and generates an image signal indicating processing results of the game application. The image signal is sent to the display apparatus <NUM> from the output section <NUM> and output as a display image.

<FIG> is a functional configuration diagram of the gaming apparatus <NUM>. The application processing section <NUM> of the gaming apparatus <NUM> includes a control section <NUM> and a data holding section <NUM>. The control section <NUM> includes a game control section <NUM>, an instruction input acquisition section <NUM>, an HMD information acquisition section <NUM>, an input apparatus information acquisition section <NUM>, a first image generation section <NUM>, and a second image generation section <NUM>.

The data holding section <NUM> holds program data of games executed in the gaming apparatus <NUM>, various data used by the game programs, and so on.

The instruction input acquisition section <NUM> acquires information related to user instruction input accepted by the input apparatus <NUM> or the head-mounted display <NUM> from the input apparatus <NUM> or the head-mounted display <NUM>.

The HMD information acquisition section <NUM> acquires information related to the attitude of the head-mounted display from the head-mounted display <NUM>. Also, the HMD information acquisition section <NUM> acquires information related to the position of the head-mounted display <NUM> from the device information deriving section <NUM>. These pieces of information are conveyed to the game control section <NUM>. Information related to the attitude of the head-mounted display <NUM> may be acquired by the device information deriving section <NUM> analyzing a captured image of the head-mounted display <NUM>.

The input apparatus information acquisition section <NUM> acquires information related to the attitude of the input apparatus <NUM>. Also, the input apparatus information acquisition section <NUM> acquires information related to the position of the input apparatus <NUM> from the device information deriving section <NUM>. These pieces of information are conveyed to the game control section <NUM>. Information related to the attitude of the input apparatus <NUM> may be acquired by the device information deriving section <NUM> analyzing a captured image of the input apparatus <NUM>.

If the input apparatus <NUM> moves out of the imaging range of the imaging apparatus <NUM> or if the input apparatus <NUM> is hidden behind the user's body or an obstacle and fails to be imaged by the imaging apparatus <NUM>, the input apparatus information acquisition section <NUM> calculates the position of the input apparatus <NUM> based on the previously acquired position of the input apparatus <NUM> and information related to the attitude of the input apparatus <NUM> acquired after that point in time. For example, the current position of the input apparatus <NUM> may be calculated by calculating a deviation from the previously acquired position of the input apparatus <NUM> based on translational acceleration data acquired from the acceleration sensor of the input apparatus <NUM>. While the input apparatus <NUM> is not imaged by the imaging apparatus <NUM>, the position of the input apparatus <NUM> is successively calculated in the similar manner. When the input apparatus <NUM> is imaged again by the imaging apparatus <NUM>, there is a possibility that the position of the input apparatus <NUM> successively calculated from acceleration data may not indicate a correct position due to cumulative drift error. Therefore, the position of the input apparatus <NUM> newly calculated by the device information deriving section <NUM> may be used as the current position of the input apparatus <NUM>. The same is true for the head-mounted display <NUM>.

The game control section <NUM> executes the game program and progresses the game based on user instruction input acquired by the instruction input acquisition section <NUM> and information related to the position or attitude of the input apparatus <NUM> or the head-mounted display <NUM>. The game control section <NUM> changes the position of a player's character, an operation target, based on input made by directional keys or an analog stick of the input apparatus <NUM> and a change in position of the input apparatus <NUM> or the head-mounted display <NUM> in a game field made up of a virtual three-dimensional (3D) space.

The first image generation section <NUM> generates an image to be displayed on the head-mounted display <NUM>. The first image generation section <NUM> generates a game field image by specifying a viewpoint position based on the position of the operation target controlled by the game control section <NUM>, specifying a direction of line of sight based on the attitude of the head-mounted display <NUM>, and rendering a virtual 3D space. The first image generation section <NUM> associates the attitude of the head-mounted display <NUM> and the direction of line of sight in the game field at a given time and changes, thereafter, the direction of line of sight with change in the attitude of the head-mounted display <NUM>. As a result, the user can look over the game field by actually moving his or her head, allowing the user to feel as if he or she were really in the game field. The first image generation section <NUM> generates a first image by adding information related to the game, an image to be displayed on the head-mounted display <NUM>, and so on to the generated game field image. The first image generated by the first image generation section <NUM> is sent to the head-mounted display <NUM> via a wireless communication module or a wired communication module.

The second image generation section <NUM> generates an image to be displayed on the display apparatus <NUM>. When the same image as displayed on the head-mounted display <NUM> is displayed on the display apparatus <NUM>, the first image generated by the first image generation section <NUM> is also sent to the display apparatus <NUM>. When an image different from the image displayed on the head-mounted display <NUM> is displayed on the display apparatus <NUM>, an example of which is when the user wearing the head-mounted display <NUM> and the user watching the display apparatus <NUM> execute a head-to-head game, the second image generation section <NUM> generates a game field image by specifying a viewpoint position and a direction of line of sight different from those specified by the first image generation section <NUM>. The second image generation section <NUM> generates a second image by adding information related to the game, an image to be displayed on the display apparatus <NUM>, and so on to the generated game field image. The second image generated by the second image generation section <NUM> is sent to the display apparatus <NUM> via a wireless communication module or a wired communication module.

<FIG> illustrates examples of images displayed on the head-mounted display. The game control section <NUM> provides a function to switch the viewpoint position between a plurality of positions specified in the game field. In the display screen depicted in <FIG>, a game field image is displayed that was generated with one of a plurality of positions specified in the game field as a viewpoint position. In the display screen, markers <NUM> and <NUM> further appear that indicate positions specified as viewpoint positions in the game field. When the user changes the attitude of the head-mounted display <NUM> by shaking his or her head horizontally and vertically, the first image generation section <NUM> changes a direction of line of sight in accordance with an attitude of the head-mounted display <NUM>. When it is rendered possible to detect the user's direction of line of sight by providing a camera for shooting the user's eyeballs inside the head-mounted display <NUM>, the direction of line of sight may be changed by further taking into account the user's line of sight. The user's line of sight may be detected by using a known and arbitrary line-of-sight tracking technology.

When the marker enters a given range specified near the center of the display screen as the user points his or her face or line of sight toward the marker direction, as depicted in <FIG>, the game control section <NUM> causes the first image generation section <NUM> to change the manner in which the marker <NUM> is displayed, thereby indicating that the position depicted by the marker <NUM> has been selected as a candidate for specifying a viewpoint position. When the user issues an instruction to change the viewpoint position, for example, by pressing a given button or performing a given gesture with the candidate for specifying a viewpoint position selected, the game control section <NUM> instructs the first image generation section <NUM> to change the viewpoint position to the position depicted by the selected marker <NUM>. The first image generation section <NUM> generates and displays a game field image having the position of the marker <NUM> as a viewpoint position as depicted in <FIG>. In the display screen depicted in <FIG>, a marker <NUM> appears that indicates the position specified as the viewpoint position in the display screen depicted in <FIG>.

<FIG> is a schematic diagram for describing a method of specifying a viewpoint position and a direction of line of sight. In the present embodiment, a viewpoint position is specified on the surface of a sphere having its center near a center of the game field, and a default direction of line of sight is specified in the direction of seeing the first position near the center of the game field from the viewpoint position. As a result, no matter where the viewpoint position is specified, it is possible to display an image that allows the game field to be overlooked. When changing the viewpoint position, the first image generation section <NUM> smoothly moves the viewpoint position along the sphere surface and generates a game field image by specifying a direction of line of sight in the direction of seeing the first position in the game field from the viewpoint position even while moving the viewpoint position. As a result, it is possible to display an image that allows the game field to be overlooked even while the viewpoint position is changed, thereby making it possible to indicate, in an easy-to-understand manner, to the user where the viewpoint position will be moved even when the viewpoint position is moved to a large extent. It should be noted that a viewpoint position may be provided on the surface of a sphere or a spheroid having its center at an arbitrary point in the game field or on a curved surface other than that. Also, when the viewpoint position is changed, the viewpoint position may be continuously changed in a linear or curved manner from the viewpoint position before the change to the viewpoint position after the change. In the example depicted in <FIG>, the surface of a lower hemisphere is underground. Therefore, a viewpoint position can be specified only on the surface of an upper hemisphere. However, when the game field is, for example, an outer space, viewpoint positions may be specified on the surface of the lower hemisphere.

<FIG> illustrates examples of images displayed on the head-mounted display. If the user moves the head-mounted display <NUM> forward by moving his or her head forward when a game field image as seen from a viewpoint position is displayed as depicted in <FIG>, the game control section <NUM> causes the first image generation section <NUM> to move the viewpoint position to a second position near the center of the game field. The game control section <NUM> may move the viewpoint position when the head-mounted display <NUM> is moved forward by as much as or more than a given amount of travel. Alternatively, the game control section <NUM> may move the viewpoint position when the head-mounted display <NUM> travels at a speed equal to or more than a given value. As a result, the viewpoint position can be moved to near the center of the game field from spectators' seats as depicted in <FIG>. Therefore, the user who was watching, for example, a soccer game from a spectator's viewpoint can feel as if he or she entered the field where the game is taking place. Also, it is possible to provide an easy-to-understand method of moving the viewpoint using the head-mounted display <NUM>.

<FIG> is a schematic diagram for describing details of another game provided by the game control section. In the game depicted in the present figure, the user hides inside a box <NUM> having holes <NUM> and pops up his or her face from a hole <NUM> while being careful not to be hit by a hammer <NUM> and reads letters written on a plate <NUM>. The game control section <NUM> changes the viewpoint position based on the position of the head-mounted display <NUM>. The game control section <NUM> determines the hole <NUM> to be hit with the hammer <NUM> at a given timing and swings down the hammer <NUM> into the determined hole <NUM>. We assume that if the hammer <NUM> is swung down into the hole <NUM> when the user's viewpoint position is above and outside the hole <NUM>, the user is hit with the hammer <NUM>. If the user is hit a given number of times or more with the hammer <NUM>, the game is over.

<FIG> depicts diagrams illustrating examples of images displayed on the head-mounted display. <FIG> depicts a game screen when the user looks up from the middle hole. The hammer is about to be swung down into the middle hole. <FIG> depicts a game screen when the user has moved the viewpoint position to under the right hole by moving the head-mounted display <NUM> to the right. Because the hammer is about to be swung down into the middle hole, the hammer will not be swung down into the right hole for a while. At this time, if the user moves up the viewpoint position from the right hole by moving up the head-mounted display <NUM>, the user can visually recognize the letters written on a plate provided outside the box as depicted in <FIG>.

<FIG> is a schematic diagram for describing a method of moving the viewpoint position in a game according to the embodiment. When the user plays a game seated, for example, in a chair, the hip position is fixed. Therefore, the user moves his or her head in a circular arc. However, the possible range of head motion that causes no hindrance to the game is approximately <NUM> to <NUM> degrees at most. In order to make effective use of the possible motion range of the head-mounted display <NUM>, therefore, the game control section <NUM> moves the viewpoint position to a greater extent when the head-mounted display <NUM> is moved horizontally than when the head-mounted display <NUM> is moved perpendicularly. Also, if the amount of travel exceeds the amount equivalent to the width of the middle hole when the head-mounted display <NUM> is moved to the left or right, the area between the middle hole and the left or right hole is skipped, moving the viewpoint position to under the left or right hole. Specifically, if the head-mounted display <NUM> is moved to the right while the viewpoint position is located under the middle hole, and when the head-mounted display <NUM> reaches a position <NUM>, the viewpoint position jumps from the right edge position of the middle hole to the left edge position of the right hole. Also, if the head-mounted display <NUM> is moved to the left while the viewpoint position is located under the right hole, and when the head-mounted display <NUM> reaches a position <NUM>, the viewpoint position jumps from the left edge position of the right hole to the right edge position of the middle hole. As a result, the viewpoint position is not moved to an area to which there is no or only a slight need to move the viewpoint position in a game, whereas the viewpoint position can be moved to only given areas to which there is need to move the viewpoint position or to which the viewpoint position is often moved, thereby making effective use of the possible motion range of the head-mounted display <NUM> and moving the viewpoint position. Also, it is possible to provide a user interface that permits movement of the viewpoint position with ease by moving the head-mounted display <NUM> even without using, for example, the input apparatus <NUM>, thereby ensuring improved user convenience. A hysteresis is provided by using different positions, the position <NUM> for causing the viewpoint position to jump for rightward movement and the position <NUM> for causing the viewpoint position to jump for leftward movement, thereby reducing the likelihood for the viewpoint position to jump to the left and right frequently when the head-mounted display <NUM> is at an angle equivalent to a position in the neighborhood of a threshold.

When an attempt is made to move the viewpoint position to above the left or right hole, it is necessary to move the head-mounted display <NUM> upward while keeping the head-mounted display <NUM> tilted to the left or right. However, it is not easy for the user to move his or her head straight upward while keeping the body tilted to the left or right. In the present embodiment, therefore, when the head-mounted display <NUM> is moved up or down in a tilted position to the left or right, and even if the direction of movement is tilted diagonally, the game control section <NUM> moves the viewpoint position vertically, but not horizontally. The game control section <NUM> moves the viewpoint position vertically by the amount of travel equivalent to a vertical component of a movement vector of the head-mounted display <NUM> and may ignore a horizontal component or move the viewpoint position vertically by the amount of travel equivalent to the magnitude of the movement vector of the head-mounted display <NUM>. Thus, when the viewpoint position is changed in response to movement of the head-mounted display <NUM>, it is possible to restrict the movement direction of the viewpoint position to a given direction and prevent the viewpoint position from moving in an unnecessary direction by converting the movement vector of the head-mounted display <NUM> into a vector in a given direction. Also, it is possible to provide a user interface that permits the movement of the viewpoint position only in a necessary direction, thereby ensuring improved user convenience.

Such a technology is applicable, for example, to a game in which a player's character hides behind an obstacle such as wall to ward off oncoming bullets.

The present invention has been described above based on an embodiment. The present embodiment is illustrative, and it is to be understood by those skilled in the art that the combination of components and processes thereof can be modified in various ways and that these modification examples also fall within the scope of the present invention.

Although an image for binocular stereopsis was displayed on the display apparatus <NUM> of the head-mounted display <NUM> in the above example, an image for monocular stereopsis may be displayed in a different example.

Although the head-mounted display <NUM> was used in a game system in the above example, the technology described in the embodiment can be also used to display content other than games.

<NUM> Gaming apparatus, <NUM> Input apparatus, <NUM> Head-mounted display, <NUM> Display apparatus, <NUM> Game control section, <NUM> Instruction input acquisition section, <NUM> HMD information acquisition section, <NUM> Input apparatus information acquisition section, <NUM> First image generation section, <NUM> Second image generation section.

Claim 1:
A display control apparatus comprising:
a display control section (<NUM>) adapted to generate a virtual space image by specifying a first viewpoint position and a direction of line of sight and display the image on a head-mounted display (<NUM>),
wherein the display control section is further configured to:
specify a plurality of positions in the virtual space as viewpoint positions, wherein the plurality of viewpoint positions are separated from each other;
change the viewpoint position from the first position to a second position determined from among the plurality of positions in accordance with an operation by a user and an attitude of the head-mounted display; and
specify, when the viewpoint position is changed, as a direction of line of sight, the direction in which the first position in the virtual space is seen from the second viewpoint position.