JP2003009039A - Image display device, image display method, information storage medium, and image display program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device, an image display method, an information storage medium, and an image display program, which project a distortionless picture on a curved surface screen. SOLUTION: An image processing part 40 is provided with a perspective projection conversion processing part 42, a texture mapping processing part 43, a plane processing part 41 having a plane buffer 44, a coordinate transformation processing part 46, and a curved surface processing part 45 having an image information read part 47. The plane processing part 41 projects the image of a three-dimensional object in a game space on five virtual planes S1 to S5 surrounding a spherical screen 4. Projected image information is stored in the plane buffer 44. The curved surface processing part 45 calculates a coordinate on the plane buffer 44 corresponding to one point on a circular frame buffer 50, and image information stored in the coordinate is read out and is stored in a corresponding position of the circular frame buffer 50. Image information is stored in respective coordinates of the circular frame buffer 50 in this manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device, an image display method, an information storage medium and an image display program for projecting an image on a curved screen through a wide-angle lens.

[0002]

2. Description of the Related Art Conventionally, an image display device for projecting an image on a non-flat screen has been known. For example, JP-A-9-81785 and JP-A-3-82493 disclose various image display devices that project an image on a non-planar screen and correct distortion of the projected image. When an image created for projection on a flat screen is directly projected on a non-flat screen, a distorted image is displayed. Therefore, in the above-described image display device, in consideration of distortion at the time of display, by generating an image that is distorted in the opposite direction in advance so that the distorted result is normal display content, a non-planar screen is displayed. The display distortion is corrected.

[0003]

By the way, in the above-mentioned conventional image display device, when the image is distorted into a convex shape by being projected on a non-planar screen, an image distorted into a concave shape is generated in advance, As a result, the distortion on the non-planar screen is corrected. However, when displaying a three-dimensional object arranged in a three-dimensional space on a non-planar screen, there is a problem that the distortion cannot be sufficiently corrected. For example, when the projection position and the viewpoint position of the image are different, the degree of distortion given to the generated image varies depending on the degree of perspective of the three-dimensional object. You can't get rid of the distortion. In particular, although it is considered that the two-dimensional image distortion correction and the three-dimensional image distortion correction are essentially different, the image display device disclosed in the above publication simply discloses a two-dimensional image distortion correction method. However, it is not possible to sufficiently remove the distortion of the image obtained by projecting the three-dimensional object on the screen only by using these methods.

The present invention was created in view of the above points, and an object thereof is an image display device, an image display method, an information storage medium, and an image storage medium capable of projecting an image with little distortion on a curved screen. To provide an image display program.

[0005]

In order to solve the above-mentioned problems, the image display device of the present invention projects an image of a three-dimensional object arranged in a virtual three-dimensional space on a curved screen through a wide-angle lens. For this purpose, it is provided with a frame buffer, a projection device, a plane processing means, and a curved surface processing means. In the frame buffer, the position to be projected on the curved screen and the storage position of the image information correspond to each other. The projection device projects an image corresponding to the image information stored in the frame buffer toward the wide-angle lens. The plane processing means performs perspective projection conversion of the three-dimensional object into a plurality of virtual planes, and stores image information corresponding to each plane in the plane buffer. The curved surface processing means reads out the image information stored in the plane buffer and stores it in the frame buffer. After perspective-projection conversion of a three-dimensional object onto a plurality of virtual planes and storing the image information in the plane buffer, the image information is transferred to the frame buffer,
In consideration of the fixed positional relationship between the virtual plane and the curved screen, it becomes possible to store the image information in the frame buffer and perform the distortion correction so that the distortion is eliminated, and the curved screen is distorted. It is possible to project an image with less image.

The wide-angle lens described above is preferably a fisheye lens. By using a fisheye lens,
Since a projection angle of almost 180 ° can be realized,
By displaying the image projected in this way on the curved screen, it is possible to project a realistic image with little distortion.

Further, the above-described curved surface processing means includes coordinate conversion means for calculating the second storage coordinates of the plane buffer corresponding to the first storage coordinates of the frame buffer, and the plane buffer by designating the second storage coordinates. Image information read from
It is desirable to include image information reading means for designating the first storage coordinates and writing in the frame buffer. The second storage coordinates of the plane buffer corresponding to the first storage coordinates of the frame buffer are calculated, and the image information stored in the second storage coordinates is read from the plane buffer and written in the frame buffer. The image information corresponding to all the pixels projected by the projection device can be efficiently read from the plane buffer and stored in the frame buffer.

Further, the coordinate conversion means described above calculates corresponding positions on a plurality of virtual planes when a position on the curved screen corresponding to the first storage coordinates of the frame buffer is viewed from a predetermined viewpoint position. It is desirable to calculate it as the second storage coordinates. The position on the virtual plane where the actual image is projected is calculated based on the image information stored in the frame buffer, and the image information stored in the plane buffer corresponding to this position is read out and the frame is read. Since it is stored in the corresponding position of the buffer, it is possible to project an accurate image with little distortion.

Further, it is desirable to make the predetermined viewpoint position and the projection position corresponding to the wide-angle lens different. In fact, it is not possible to see the image on the curved screen from the projected position. Therefore, by performing the distortion correction on the premise that the viewpoint position and the projection position are different, it is possible to project an image with less distortion under conditions that match actual conditions.

Further, when the projection position is set to be displaced from the center position of the curved screen, the above-mentioned curved surface processing means considers the distance between the projection position and the position to be projected on the curved screen, and It is desirable to perform brightness correction on the image information stored in the buffer. When the projection position is deviated from the center position, the brightness of the projected image is biased even when an image with uniform brightness is projected. Therefore, by performing the brightness correction in consideration of the distance, it is possible to eliminate the unevenness of the brightness and obtain an image having a substantially uniform brightness.

Further, the apparatus further comprises an object calculation means for calculating the position information of the three-dimensional object in the virtual three-dimensional space at predetermined intervals, and the process of storing the image information in the frame buffer is repeated at predetermined intervals. Is desirable. When a three-dimensional object moves or moves in a virtual three-dimensional space, the coordinates of the three-dimensional object are calculated at predetermined intervals and an image without distortion is generated each time. It is possible to project a distortion-free moving image on a curved screen in a game or presentation using the original object.

Further, the image display method of the present invention comprises a first step of performing perspective projection conversion of a three-dimensional object into a plurality of virtual planes, and storing image information corresponding to each plane in a plane buffer. The second step of reading the image information stored in the buffer and writing it in the corresponding area of the frame buffer storing the image information corresponding to the position to be projected on the curved screen, and the image information stored in the frame buffer And a third step of reading and projecting through a wide-angle lens onto a curved screen.

The information storage medium of the present invention includes a program for executing the first step to the third step. Further, the image display program of the present invention causes the computer to execute the first step to the third step in order to project the image of the three-dimensional object arranged in the virtual three-dimensional space on the curved screen through the wide-angle lens. It is meant to be executed.

By implementing the image display method of the present invention, or by executing the program stored in the information storage medium of the present invention or the image display program of the present invention, an image with little distortion is projected on the curved screen. can do. Also, in the second step described above,
It is desirable to calculate the corresponding positions of the frame buffer and the plane buffer in consideration of the predetermined viewpoint position. Since the position on the virtual plane on which the actual image is projected is calculated based on the image information stored in the frame buffer in consideration of the viewpoint position, an image with less distortion can be projected.

In the above-mentioned second step,
It is desirable to calculate the corresponding position of the frame buffer and the plane buffer in consideration of the predetermined viewpoint position and the projection position corresponding to the position of the wide-angle lens. The position on the virtual plane where the actual image is projected based on the image information stored in the frame buffer is calculated by considering both the viewpoint position and the projection position, so an image with less distortion is projected. can do.

Further, when the projection position is set to be displaced from the center position of the curved screen, the distance between the projection position and the position to be projected on the curved screen is taken into consideration and the image information stored in the frame buffer is stored. It is desirable to insert the fourth step of performing brightness correction before the third step. By performing the brightness correction in consideration of the distance, it is possible to eliminate an uneven brightness and obtain an image having a substantially uniform brightness.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A game system according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of the game system of the present embodiment. The game system shown in the figure includes a game device 1, a projector 2, a lens 3, and a spherical screen 4.

The game apparatus 1 performs various game calculations in response to the player's operation and generates image information for displaying a game image according to the progress of the game. The projector 2 irradiates the spherical screen 4 with a game image based on the image information generated by the game device 1. The lens 3 projects the game image emitted from the projector 2 onto the spherical screen 4. In this embodiment, a wide-angle lens, more specifically, a fisheye lens having a projection angle of about 180 ° is used as the lens 3. The spherical screen 4 is a kind of curved screen, has a hemispherical projection surface, and a game image emitted from the projector 2 and passing through the lens 3 is projected inside.

Next, the detailed structure of the game apparatus 1 will be described. The game device 1 shown in FIG. 1 includes an input device 10, a game calculation unit 20, an information storage medium 30, an image processing unit 40,
It is configured to include a circular frame buffer 50. The input device 10 is for a player to input various instructions to the game device 1, and is configured to include various operation keys, operation levers, and the like according to the type of game played in the game device 1. There is. For example, the input device 10 provided for playing a drive game is provided with a handle, an accelerator, a brake, a gear shift lever, and the like.

The game calculation section 20 performs a predetermined game calculation necessary for the progress of the game. The game calculation section 20 includes an input determination section 22, an event processing section 24, and a game space calculation section 26. The game calculation unit 20 is realized by executing a predetermined game program using a semiconductor memory such as a CPU, a ROM, and a RAM.

The input determination unit 22 determines the operating state of the steering wheel, accelerator, brake, etc. provided in the input device 10, and outputs a signal corresponding to the operating state to the event processing unit 24. The event processing unit 24 generates various events,
Performs processing necessary for game progress, such as branching decisions corresponding to the progress of the game. The game space calculation unit 26 calculates position information of various three-dimensional objects existing in the game space, which is a virtual three-dimensional space. Each of the three-dimensional objects in the present embodiment is composed of a plurality of polygons, and the game space calculation unit 26 calculates the vertex coordinates of each polygon forming the three-dimensional object.

The information storage medium 30 is for storing programs and data for operating the game apparatus 1 having a function as a computer. Specifically, the information storage medium 30 stores a game program executed by the game calculation unit 20, data necessary for displaying a game image (texture data for texture mapping, etc.), and an image display program. The information storage medium 30 is realized by a CD-ROM, a DVD-ROM, a hard disk device, a semiconductor memory or the like.

The image processing unit 40 receives the vertex coordinates of each polygon calculated by the game space calculation unit 26 in the game calculation unit 20 and, in order to display an image on the spherical screen 4, a circular frame buffer. A process of storing image information in 50 is performed. The image processing unit 40 includes a plane processing unit 41 and a curved surface processing unit 45. The plane processing unit 41 projects the image of the three-dimensional object arranged in the game space onto a plurality of virtual planes circumscribing the spherical screen 4. The curved surface processing unit 45 is the flat surface processing unit 41.
The image information to be stored in the circular frame buffer 50 is created based on the two-dimensional image projected on the virtual plane.

The image processing unit 40 is realized by using a dedicated graphic LSI, DSP, or the like, but when the performance of the CPU for realizing the game calculation unit 20 is high and the processing capacity is sufficient. May cause the CPU to perform the processing of the image processing unit 40.

FIG. 2 is a view showing a virtual plane used for the projection processing by the plane processing unit 41. As shown in the figure, in this embodiment, five planes S1, S2, S3, S4 and S5 circumscribing the hemispherical spherical screen 4 are considered. These five planes S1 to S5 correspond to respective surfaces when a rectangular parallelepiped circumscribing the sphere including the spherical screen 4 is cut in half, and adjacent ones intersect each other at right angles.

The plane processing unit 41 is a perspective projection conversion processing unit 4.
2, texture mapping processing unit 43, plane buffer 4
4 is included. Perspective projection conversion processing unit 42
Is a perspective projection conversion process for setting the spherical center position of the spherical screen 4 as a virtual viewpoint position and projecting various three-dimensional objects arranged in the game space onto each of the five planes S1 to S5 described above. I do. In this embodiment, each of the three-dimensional objects is composed of one or a plurality of polygons, and by this perspective projection conversion processing, the vertex coordinates of each polygon arranged in the game space are assigned to each of the planes S1 to S5. A coordinate conversion process of projecting is performed.

FIG. 3 and FIG. 4 are diagrams showing specific examples of perspective projection conversion. The perspective projection transformation on the square plane S1 is performed by projecting the three-dimensional object 200 arranged in the game space onto the plane S1, as shown in FIG. As for the perspective projection conversion for the other planes S2 to S5, as shown in FIG. 4, it is sufficient to use the perspective projection conversion for only the upper half of the square plane as in the processing for the plane S1.

The texture mapping processing section 43 carries out a processing (texture mapping processing) of pasting the inside of each polygon with texture data to each polygon for which the vertex positions on the planes S1 to S5 are calculated by the perspective projection conversion. In this way, the process of projecting the three-dimensional object on each of the planes S1 to S5 is performed, and the obtained two-dimensional image information is stored in the plane buffer 44.

Since the perspective projection conversion processing and the texture mapping processing described above have the same contents as those conventionally performed, existing hardware that has been developed and sold for three-dimensional image processing is used. Or software can be used as is.

The curved surface processing section 45 creates coordinates for the image information to be stored in the circular frame buffer 50 based on the image information obtained for each of the five planes S1 to S5 shown in FIG. It has a conversion processing unit 46 and an image information reading unit 47. The circular frame buffer 50
The image information obtained by the curved surface processing unit 45 is stored.
Each storage position of the circular frame buffer 50 corresponds to each position to be projected on the spherical screen 4,
By storing the image information in a predetermined position of the circular frame buffer 50, the image of the color specified by this image information is projected on the corresponding position on the spherical screen 4.

The coordinate conversion processing unit 46 performs a coordinate conversion process for calculating the storage position of the corresponding plane buffer 44 based on each storage position of the circular frame buffer 50. Figure 5
FIG. 6 is a diagram showing an outline of coordinate conversion processing performed by the coordinate conversion processing unit 46. For example, there is a viewpoint position and a projection position at the spherical center o of the spherical screen 4, and a point P in the game space
The corresponding position when perspective projection transformation is performed on the plane S
It is assumed to exist above 1. If the point where the straight line passing through the ball center o and the point P in the game space and the plane S1 intersect is P _q , the image information corresponding to this point P _q is the plane buffer 44.
Is stored in the storage position H of. Further, when the point where the the straight line and the spherical screen 4 intersects the P _d, the image projected in this respect P _d is, the storage position of the circular frame buffer 50 F
Need to be stored in. The coordinate conversion processing unit 46 calculates the storage position H of the plane buffer 44 corresponding to the storage position F of the circular frame buffer 50.

The image information reading section 47 is provided in the plane buffer 4
Based on the relationship between the storage position H of the plane buffer 44 and the storage position F of the circular frame buffer 50 calculated by 4, the image information stored in the plane buffer 44 is read and stored in the circular frame buffer 50.

The above-described projector 2 is a projection device, the plane processing unit 41 is plane processing means, the curved surface processing unit 45 is curved surface processing means, the coordinate conversion processing unit 46 is coordinate conversion means, and the image information reading unit 47 is an image. The game space computing section 26 corresponds to the information reading means and the object computing means.

The game system of this embodiment has such a configuration, and its operation will be described below. FIG. 6 is a flow chart showing the outline of the operation procedure of the game system of the present embodiment, and shows the flow of the entire game.
The series of processing shown in FIG. 6 is repeatedly performed at a cycle (for example, 1/60 seconds) corresponding to a predetermined display interval.

When the player gives an instruction to start a game by operating the input device 10, the game calculation section 20
Starts a predetermined game calculation based on the game program read from the information storage medium 30. In particular,
The input determination unit 22 in the game calculation unit 20 is the input device 10
Based on the signal output from the player, a predetermined input determination process of outputting a signal according to the content of the operation performed by the player is performed (step 100).

Next, the event processing section 24 generates various events necessary for the progress of the game in response to the signal output from the input determination section 22 (event generation processing).
Is performed (step 101). In addition, the game space calculation unit 2
6 performs coordinate calculation of various three-dimensional objects existing in the game space, corresponding to the event generation processing performed by the event processing unit 24 (step 102).
By this coordinate calculation, the vertex coordinates of a plurality of polygons forming the three-dimensional object are calculated.

In this way, when the coordinate calculation of each three-dimensional object is performed by the game space computing section 26 and the position information of the three-dimensional object is acquired, the image processing section 4
The plane processing unit 41 in 0 performs perspective projection conversion with reference to a predetermined viewpoint position to generate five virtual planes S1 to S5.
The image information corresponding to each of these is stored in the plane buffer 44 (step 103). Specifically, the perspective projection conversion processing unit 42 calculates the vertex coordinates of each polygon forming the three-dimensional object in the game space, the texture mapping processing unit 43 obtains the image information inside the polygon, and this image information is obtained. It is stored in the plane buffer 44.

Next, the curved surface processing unit 45 performs coordinate conversion processing for calculating the storage position on the plane buffer 44 corresponding to each storage position of the circular frame buffer 50 (step 104), and based on this calculation result. , Plane buffer 44
The image information stored in is stored in the corresponding storage position on the circular frame buffer 50 (step 1
05).

The image information written in the circular frame buffer 50 is read out in a predetermined scanning order and sent to the projector 2. The projector 2 forms an image based on this image information and projects it on the spherical screen 4 through the lens 3 (step 106).

In this way, a game image having new contents is generated at a predetermined repetition period and projected on the spherical screen 4. In the above description of the operation, the drawing process is performed by performing the series of processes illustrated in FIG. 6 at a cycle corresponding to the display interval, but the display interval and the repeating interval of the drawing process do not necessarily have to match. Good. In addition, if the drawing process is in time for the display timing, the drawing process is performed in synchronization with the display timing each time, and if the drawing process is not in time, the same content is displayed on the screen. May not match.

Next, details of the coordinate conversion process in step 104 described above will be described. (1) Both the viewpoint position and the projection position of the spherical screen 4
Case of Setting to the Ball Center Position The case where the ball center o of the spherical screen 4 has both the viewpoint position and the projection position as shown in FIG. 5 will be described.

First, the point F on the circular frame buffer 50
Projection point P _d on the spherical screen 4 corresponding to (X, Y)
Find (x _d , y _d , z _d ). In the lens 3 used in this embodiment, the distance L from the center point O of the circular frame buffer 50 to the point F (X, Y) is a straight line connecting the origin o shown in FIG. 5 and the point P _d on the spherical screen 4. And the z-axis
It has a property proportional to. The angle φ formed with the x axis is the same as the angle Φ formed by the straight line connecting the center point O and the point F in the circular frame buffer 50 and the X axis. Based on this property, the coordinates x _d , y _d , and z _d of the point P _d are obtained. In the formula shown below, the singular point is 0 when the denominator is 0 when X = 0 and Y = 0. For such a combination of the X coordinate and the Y coordinate, the projected point on the spherical screen 4 is It is necessary to obtain P _d separately. For example, in the example shown in FIG.
The point on the spherical screen 4 that intersects the z axis passing through the spherical center o of the spherical screen 4 may be obtained as P _d .

First, the projection point P _d is displayed in polar coordinates as follows.

[0044]

[Equation 1]

Next, when θ, cosφ, and sinφ are obtained from the definition of the circular frame buffer, the following is obtained.

[0046]

[Equation 2]

[0047] Thus, each coordinate x _d of the point P _d, y _d, z _d
Is as follows.

[0048]

[Equation 3]

Next, a straight line passing through the origin o and the point P _d shown in FIG. 5, obtains the intersection of the plane S1-S5. Origin o and point P
_The straight line passing through _d is

[0050]

[Equation 4]

It can be expressed by the equation: This (10)
In order to obtain the intersections of the straight line represented by the equation and the respective planes S1 to S5, this straight line and the respective planes S1 to S1 shown below are obtained.
It suffices to solve the equations by simultaneous equations of S5. Plane S1: z = r (where -r≤x≤r, -r≤y≤
r) plane S2: y = r (provided that -r≤x≤r, 0≤z≤r) plane S3: x = r (provided that -r≤y≤r, 0≤z≤r) plane S4: x = -R (where -r≤y≤r, 0≤z≤
r) plane S5: y = −r (where −r ≦ x ≦ r, 0 ≦ z ≦
r) For example, if r = 1 to simplify the calculation, the point P _d
The intersection point P _q (x _q , y _q , z _q ) of the straight line passing through and the plane S1 is obtained as follows.

[0052]

[Equation 5]

From these equations, x = x _d / z _d , y = y _d
/ Z _d . These x, if y is both included in the range from -1 to 1 is that the straight line and the plane S1, passing through the point P _d intersect, the coordinates x _q,
y _q and z _q are

[0054]

[Equation 6]

It becomes Here, the values of x _d , y _d , and z _d are
As shown in the equations (7) to (9), since the point F (X, Y) on the circular frame buffer 50 is uniquely determined, the coordinates (storage position) of the point F on the circular frame buffer 50 are set. Based on that, the corresponding points on the plane S1 can be calculated. It should be noted that the intersections can be similarly obtained for the other planes S2 to S5. However, since only one plane actually intersects the straight line passing through the point P _d , only one intersection satisfying the condition is finally obtained.

In this way, the coordinate conversion processing unit 46 in the curved surface processing unit 45 calculates the coordinates of one point P _q on the plane buffer 44 corresponding to one point F on the circular frame buffer 50. The image information reading unit 47 obtains the calculated coordinates (x _q , y _q , z _q ) of the point P _q , reads the image information stored in this coordinate of the plane buffer 44, and reads the circular frame buffer 50. It is stored in the coordinates (X, Y).

FIG. 7 is a diagram showing the correspondence between arbitrary points in the circular frame buffer 50 and the five virtual planes S1 to S5. As shown in FIG. 7, the predetermined area (S1) including the origin O of the circular frame buffer 50 corresponds to the plane S1 shown in FIG. 2, and on the plane S1 based on the coordinates of any point in this area. The coordinates of one point are obtained. The same applies to other areas, and (S2) to (S5) in FIG.
2 correspond to the planes S2 to S5 shown in FIG. 2, respectively, and the coordinates of one point included in any of the planes S2 to S5 based on the coordinates of any point in each area. Is required.

(2) Only the projection position of the spherical screen 4
By the way, in the above description, the case where the viewpoint position and the projection position coincide with the spherical center of the spherical screen 4 is considered, but it is actually difficult to realize such a positional relationship.
Considering a practical geometrical arrangement, when a player wants to show a highly realistic game image by using the spherical screen 4, the viewpoint position of the player should be set near the spherical center of the spherical screen 4. Is desirable. Therefore, in this case, it is necessary to set the projection position so as to deviate from the spherical center of the spherical screen 4. However, the projection position P
each axis around the P _r point when shifted _r from the sphere center of the spherical screen 4, the original x-axis, y-axis is obtained by translating the z-axis, it is assumed that there is no axial rotation around .

FIG. 8 is a diagram showing an outline of the coordinate conversion processing when the projection position is shifted from the spherical center of the spherical screen 4. In FIG. 8, the projection position is P _r (x _r , y _r , z _r ). The actual projection surface of the spherical screen 4 is S, and the virtual projection surface centered on the projection point P _r is S ′.

F on the point on the circular frame buffer 50
(X, Y), projection point is P_r(X_r, Y_r, Z_r)
And the viewpoint P_ePoint P on the virtual projection plane S ′ seen from
_d0(X_d0, Y _d0, Z_d0) Can be expressed as
Wear.

[0061]

[Equation 7]

Projection vector of projector 2 (projection point P
The equation of a straight line that is parallel to the vector having _r as the start point and the point P _d0 as the end point and that passes through the projection point P _r is as follows.

[0063]

[Equation 8]

This straight line and the sphere equation r ² = x ² + y ² +
Find the intersection with the spherical screen 4 represented by z ² . (1
When the formula (5) is transformed, it becomes as follows.

[0065]

[Equation 9]

Therefore,

[0067]

[Equation 10]

X obtained by solving this equation is (1
The two points obtained by substituting in equation (6) are S ₁ (x ₁ , y ₁ ,
z ₁ ) and S ₂ (x ₂ , y ₂ , z ₂ ). Of the two vectors connecting these points and the projection point P _r (x _r , y _r , z _r ), the vector having the same direction as the above-mentioned projection vector is extracted, and the point S ₁ corresponding to this extracted vector is extracted. Or S ₂
Is again defined as a point P _d ′ (x _d ′, y _d ′, z _d ′). A straight line passing through the origin o and the point P _d ′ is

[0069]

[Equation 11]

This straight line and the plane S1 to
The intersection point _Pq 'with S5 ( _xq ', _yq ', _zq ') can be obtained. Note that there may be a plurality of intersections between the above-described straight line and the planes S1 to S5. In this case, the origin o is the origin of the plurality of vectors having the origin o as the start point and each of these intersections as the end point. A vector having the same direction as the vector having the start point and the point P _d ′ (or P _d0 ) as the end point may be extracted, and the intersection point corresponding to the extracted vector may be set as the point P _q ′.

When the projection position deviates from the spherical center of the spherical screen 4, the coordinate conversion processing unit 46 in the curved surface processing unit 45 thus makes the plane buffer 44 corresponding to one point F on the circular frame buffer 50. The coordinates of one point P _q ′ on the top can be calculated. The image information reading unit 47 acquires the calculated coordinates (x _q ′, y _q ′, z _q ′) of the point P _q ′, reads the image information stored in the coordinates of the plane buffer 44, It is stored in the coordinates (X, Y) of the circular frame buffer 50.

(3) Both the viewpoint position and the projection position are spherical surfaces.
When deviated from the sphere center of the clean 4, by the way, in the above description in (2), the case where the projection position P _r is set at a position deviated from the sphere center position of the spherical screen 4 has been described. In some cases, the player's viewpoint position P _e may also need to be shifted from the spherical center position of the spherical screen 4. Below, a case will be described in which both the viewpoint position and the projection position are set so as to be shifted from the spherical center position of the spherical screen 4.

Up to now, the case where the viewpoint is at the center of the spherical screen 4 has been considered, but when the viewpoint moves, the relationship between the spherical screen 4 and the viewpoint and the planes S1 to S5 changes. . When the viewpoint is at the spherical center position of the spherical screen 4, the planes S1 to S5 are considered to be circumscribing the spherical screen 4 with the spherical center position as a base point.
When the viewpoint is moving, the planes S1 to S5 with the viewpoint as the base point (center) are considered.

FIG. 9 shows the spherical screen 4 and the planes S1 to S5 when the viewpoint deviates from the spherical center position of the spherical screen 4.
It is a figure which shows the positional relationship with. The spherical screen 4 having the point o as the sphere center is shown by a dotted line, and the plane circumscribing the spherical screen 4 is shown by a dashed line. Viewpoint P _e (x _e , y _e , z _e )
Is moving from the origin o (in FIG. 9, the viewpoint P _e is moving in the positive direction along the x axis, in the negative direction along the y axis, and in the negative direction along the z axis). Viewpoint P _e as shown in FIG.
Suppose planes S1 to S5 centered on. These planes S1~S5 are perspective P _e is a plane S1~S5 that is set when a the sphere center position of the spherical screen 4, and translated by the longitudinal element component in the case of just moving the viewpoint P _e Think of it as something. In this process, the viewpoint is the origin o
Same as in. Therefore, the above (2)
The point P _d ′ on the spherical screen 4 can be obtained in the same manner as in the case where the viewpoint position is not moved as shown in FIG.

The equation of a straight line parallel to the vector connecting the viewpoint P _e and the point P _d ′ and passing through the viewpoint P _e is as follows.

[0076]

[Equation 12]

[0077] The straight line P _q that intersection sought between the plane _{S1~S5 '(x q', y} q ', z q') becomes. Plane S1
Since it is considered that S5 is translated in parallel by the amount of movement of the viewpoint P _e from the origin o as described above, it is necessary to note that the equation of each surface is also changed accordingly.

[0078] plane _{S1: z = r + z e} ( however, -r + x _e
≦ x ≦ r + x _e , −r + y _e ≦ y ≦ r + y _e ) Plane S2: y = r + y _e (where −r + x _e ≦ x ≦ r + x
_{e, z e ≦ z ≦ r} + z e) plane _{S3: x = r + x e} ( _{where, -r + y e ≦ y ≦} r + y
_{e, z e ≦ z ≦ r} + z e) plane _{S4: x = -r + x e} ( _{where, -r + y e ≦ y ≦} r +
y _e , z _e ≦ z ≦ r + z _e ) Plane S5: z = −r + y _e (where −r + x _e ≦ x ≦ r +
_{x e, z e ≦ z ≦} r + z e) As in the case of the aforementioned (2), there is a case where the intersection of the straight line and the plane S1~S5 described above there are a plurality, in this case, viewpoint P _e a starting point, among the plurality of vectors to an end point of each of these intersections, starting from the viewpoint P _e, to extract a vector of the same direction as vector and ending point P _d ', corresponding to the extracted vector The point of intersection may be the above-mentioned point P _q ′.

As described above, in the game system of this embodiment, the image information of the three-dimensional object is once projected onto the five planes S1 to S5 circumscribing the spherical screen 4 and stored in the plane buffer 44. Plane buffer 44
The image information stored in is transferred to the circular frame buffer 50. In the projection processing on the planes S1 to S5 and the transfer processing to the circular frame buffer 50, the viewpoint position and the projection position are considered, and the shape of the three-dimensional object when viewed from the viewpoint position is accurately determined. Since it is reproduced, the distortion of the image projected on the spherical screen 4 can be reduced.

Particularly, the three-dimensional object is set to the planes S1 to S.
For the process of projecting on each of the above 5, since the conventional game system can use the calculation method and the dedicated hardware that are widely used in the field of computer graphics, etc., the process of this part can be speeded up. At the same time, the cost can be reduced by reducing the labor of development of this part.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the embodiment described above,
As shown in FIG. 2, the case where the image of the three-dimensional object arranged in the game space is projected on the five planes S1 to S5 circumscribing the projection surface S of the spherical screen 4 has been considered. S5 to S5 do not necessarily need to be circumscribed on the projection surface S, and may be inscribed or five planes S1 to S5 whose distance from the origin o has any other value. Further, in the above-described embodiment,
Five planes S1 to S5 that are adjacent to each other and are perpendicular to each other
However, they may intersect at an angle other than vertical. In this case, the number of planes may be other than five. For example, if an image of a three-dimensional object is projected on each surface except the triangular pyramid-shaped bottom surface, the number of planes is three.

When the projection position P _r is set so as to be displaced from the spherical center position of the spherical screen 4, the projection position P _r is set.
The brightness may be corrected for the image information stored in the circular frame buffer 50 in consideration of the distance from the position P _d (or P _d ′) on the spherical screen 4.

FIG. 10 is a view for explaining a modified example of performing brightness correction, and shows a state in which the cross section of the spherical screen 4 is simplified. When the projection position P _r deviates from the spherical center position Q of the spherical screen 4, the projection position P _r
The distance from _r to any position on the spherical screen 4 is not equidistant. For example, as shown in FIG. 10, the distance D1 from the projection position P _r to a certain point P _d1 on the spherical screen 4 and the distance D2 to another point P _d2 are significantly different. Since the intensity of the light emitted from the projection position P _r (the light corresponding to each pixel forming the game image), that is, the brightness, is inversely proportional to the square of the distance, the spherical screen 4
The brightness of the game image displayed above will be biased.

Therefore, for example, a predetermined coefficient inversely proportional to the square of the distance from the projection position P _r to the position on the spherical screen 4 is set, and this is set to the circular frame buffer 50.
By multiplying the image information stored in, the brightness of the image information can be corrected. As a result, it is possible to reduce the bias in the brightness of the game image and project a higher quality game image.

As a simpler method, for example,
A predetermined coefficient that is inversely proportional to the distance from the projection position P _r to the position on the spherical screen 4 may be set, and this may be multiplied with the image information stored in the circular frame buffer 50. In this case, the deviation of the brightness of the game image can be reduced to some extent, and the amount of calculation required for the brightness correction can be reduced. Further, since the projection angle also has a predetermined correlation with the distance from the projection position to the position projected on the spherical screen 4, the brightness may be corrected by using the projection angle instead of the distance. The brightness correction processing as described above is performed by the image information reading unit 47 in the curved surface processing unit 45,
There may be a case where a correction processing unit that performs brightness correction is newly added to perform the correction.

In the above embodiment, the case where the image is projected on the spherical screen, which is a kind of curved screen, is explained. However, when the three-dimensional object arranged in the game space is seen from the viewpoint position, the curved surface is curved. The present invention can be applied to a case where an image is displayed on a curved screen other than a spherical surface when the position projected on the screen is obtained by calculation. For example, the image may be projected on a curved screen having a projection surface obtained by cutting a rotating body obtained by rotating an ellipse in half. Even when such a curved screen is used, the circular frame buffer 5
The coordinate conversion processing unit calculates the coordinates on the curved screen corresponding to one point F on 0 and the coordinates of the point where the straight line connecting the one point on the curved screen and the viewpoint position intersects the planes S1 to S5. The coordinate conversion processing by 46 can be performed.

Further, in the above-mentioned embodiment, the example in which the present invention is applied to the game system has been described. However, the present invention is applied to various apparatuses for projecting a three-dimensional image using a three-dimensional object on a curved screen. Can be applied. For example, the present invention can be applied to a device that gives a presentation using a three-dimensional object, various simulator devices such as a flight simulator, and the like.

[0088]

As described above, according to the present invention, a perspective projection transformation of a three-dimensional object is performed on a plurality of virtual planes to store image information in a plane buffer, and then the image information is transferred to a frame buffer. In consideration of the fixed positional relationship between the virtual plane and the curved screen, it becomes possible to store the image information in the frame buffer so as to eliminate the distortion and perform the distortion correction, An image with less distortion can be projected on a curved screen.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a game system according to an embodiment.

FIG. 2 is a diagram showing a virtual plane used for projection processing by a plane processing unit.

FIG. 3 is a diagram showing a specific example of perspective projection conversion.

FIG. 4 is a diagram showing a specific example of perspective projection conversion.

FIG. 5 is a diagram showing an outline of coordinate conversion processing performed by a coordinate conversion processing unit.

FIG. 6 is a flowchart showing an outline of an operation procedure of the game system.

FIG. 7 is a diagram showing a correspondence relationship between an arbitrary point in a circular frame buffer and five virtual planes.

FIG. 8 is a diagram showing an outline of coordinate conversion processing when the projection position is displaced from the spherical center of the spherical screen 4.

FIG. 9 is a diagram showing an outline of coordinate conversion processing when the viewpoint position is shifted from the spherical center position of the spherical screen.

FIG. 10 is a diagram illustrating a modified example of performing brightness correction.

[Explanation of symbols] 1 game device 2 projector 3 lenses 4 spherical screen 10 Input device 20 Game calculator 22 Input judgment section 24 Event processing section 26 Game Space Operation Unit 30 Information storage medium 40 Image processing unit 41 Flat processing unit 42 perspective projection conversion processing unit 43 Texture Mapping Processing Unit 44 plane buffer 45 Curved surface processing unit 46 Coordinate conversion processing unit 47 Image information reading section 50 circular frame buffer

Front page continuation (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) G06T 17/40 G06T 17/40 AF term (reference) 2C001 BA05 BC05 BC08 CB01 CC00 CC01 CC06 5B050 AA09 BA07 BA09 BA18 EA13 EA27 FA02 5B057 AA20 CA13 CB13 CC01 CD12 CD17 CH01 CH11 DA16 DB03 5C058 BA06 BA27 BB13 BB25 EA02 EA12 EA31

Claims (19)

[Claims] 1. An image display device for projecting an image of a three-dimensional object arranged in a virtual three-dimensional space on a curved screen through a wide-angle lens, and storing a position to be projected on the curved screen and image information. A frame buffer having corresponding positions; a projection device for irradiating an image corresponding to the image information stored in the frame buffer toward the wide-angle lens; and a perspective projection of the three-dimensional object onto a plurality of virtual planes. Plane processing means for converting and storing image information corresponding to each plane in a plane buffer; and curved surface processing means for reading the image information stored in the plane buffer and storing it in the frame buffer. An image display device characterized by. 2. The image display device according to claim 1, wherein the wide-angle lens is a fisheye lens. 3. The curved surface processing means according to claim 1, wherein the curved surface processing means calculates a second stored coordinate of the plane buffer corresponding to a first stored coordinate of the frame buffer, and the second coordinate conversion means. An image information reading unit for writing the image information read out from the plane buffer by designating the storage coordinates thereof into the frame buffer by designating the first storage coordinate. 4. The coordinate conversion means according to claim 3, wherein the coordinate conversion means is the first buffer of the frame buffer.
An image characterized by calculating, as the second stored coordinates, corresponding positions on the virtual plurality of planes when the position on the curved screen corresponding to the stored coordinates is viewed from a predetermined viewpoint position. Display device. 5. The image display device according to claim 1, wherein a predetermined viewpoint position and a projection position corresponding to the wide-angle lens are different. 6. The curved surface processing means according to claim 5, wherein when the projection position is set to be displaced from the center position of the curved screen, the curved surface processing unit determines the projection position and the position to be projected on the curved screen. The image display device is characterized in that brightness correction is performed on the image information stored in the frame buffer in consideration of the distance. 7. The object calculation unit according to claim 1, further comprising an object calculation unit that calculates position information of the three-dimensional object in the virtual three-dimensional space at predetermined intervals. An image display device, wherein the storage process of the image information is repeated at the intervals. 8. A first step of performing perspective projection conversion of a three-dimensional object onto a plurality of virtual planes and storing image information corresponding to each plane in a plane buffer, and an image stored in the plane buffer. The second step of reading the information and writing it in the corresponding area of the frame buffer that stores the image information corresponding to the position to be projected on the curved screen; and reading the image information stored in the frame buffer through the wide-angle lens. And a third step of projecting onto the curved screen. 9. The image display method according to claim 8, wherein in the second step, a corresponding position between the frame buffer and the plane buffer is calculated in consideration of a predetermined viewpoint position. 10. The correspondence position between the frame buffer and the plane buffer according to claim 8, in the second step, in consideration of a predetermined viewpoint position and a projection position corresponding to the position of the wide-angle lens. An image display method characterized by: 11. The method according to claim 10, wherein when the projection position is set to be displaced from the center position of the curved screen, the distance between the projection position and the position to be projected on the curved screen is considered. An image display method characterized in that a fourth step of correcting the brightness of the image information stored in the frame buffer is inserted before the third step. 12. A first step of performing perspective projection conversion of a three-dimensional object onto a plurality of virtual planes and storing image information corresponding to each plane in a plane buffer, and an image stored in the plane buffer. The second step of reading the information and writing it in the corresponding area of the frame buffer that stores the image information corresponding to the position to be projected on the curved screen; and reading the image information stored in the frame buffer through the wide-angle lens. An information storage medium including a program for executing the third step of projecting onto the curved screen, and the third step. 13. The information storage medium according to claim 12, wherein in the second step, corresponding positions of the frame buffer and the plane buffer are calculated in consideration of a predetermined viewpoint position. 14. The method according to claim 12, wherein in the second step, a corresponding position of the frame buffer and the plane buffer is calculated in consideration of a predetermined viewpoint position and a projection position corresponding to the position of the wide-angle lens. An information storage medium characterized by: 15. The distance between the projection position and a position to be projected on the curved screen according to claim 14, when the projection position is set to be displaced from the center position of the curved screen. An information storage medium including a program for executing the fourth step of correcting the brightness of the image information stored in the frame buffer before the third step. 16. A computer for projecting an image of a three-dimensional object arranged in a virtual three-dimensional space onto a curved screen through a wide-angle lens, and perspective projection conversion of the three-dimensional object onto the plurality of virtual planes. Then, the first step of storing the image information corresponding to each plane in the plane buffer, and the image information corresponding to the position to be projected on the curved screen by reading the image information stored in the plane buffer A second step of writing in a corresponding area of a frame buffer for storing the image data, and a third step of reading out the image information stored in the frame buffer and projecting the image information onto the curved screen through the wide-angle lens. Image display program. 17. The image display program according to claim 16, wherein, in the second step, a corresponding position of the frame buffer and the plane buffer is calculated in consideration of a predetermined viewpoint position. 18. The corresponding position of the frame buffer and the plane buffer according to claim 16, in the second step, in consideration of a predetermined viewpoint position and a projection position corresponding to the position of the wide-angle lens. Image display program for 19. The method according to claim 18, wherein when the projection position is set to be displaced from the center position of the curved screen, the distance between the projection position and the position to be projected on the curved screen is considered. An image display program for executing the fourth step of correcting the brightness of the image information stored in the frame buffer before the third step.