JPH11120376A - Three-dimensional image processor and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a required three-dimensional image even when memory capacity to be secured in a Z buffer is insufficient and to simultaneously change depth accuracy of the three-dimensional image to be displayed if necessary. SOLUTION: The Z buffer to store a Z value (depth information) to perform three-dimensional display of an image is secured in an off screen area 72. A range of an area in which an implicit-surface processing (three-dimensional processing) is performed and the depth of the Z buffer are set from an input device in an implicit-surface setting register 21 according to the size of the Z buffer to be secured in the off screen area 72. Z value data supplied with a system bus 10, when it is within an area set in the register 21, is transformed into the Z value data with the set depth and written in an implicit-surface processing control part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional image processing apparatus and method, and more particularly to allocating a Z-buffer storing depth information and setting a Z-buffer depth.

[0002]

2. Description of the Related Art In computer graphics,
As one method of displaying a three-dimensional image on a display device, a hidden surface elimination method is known. Among the hidden surface elimination methods, the Z buffer method, whose processing is relatively simple, is widely used. In the Z-buffer method, a two-dimensional image with hidden surfaces removed is shaded to display a three-dimensional image. Therefore, a Z-buffer that stores depth information (Z value) for each pixel is required over the entire display area of the image. . In order to increase the display accuracy of an image, a sufficient depth is required for the Z buffer, and a large-capacity memory is required for the entire system.

Techniques for reducing the required memory capacity in such a Z-buffer method include, for example, a hidden surface erasing processing device disclosed in Japanese Patent Application Laid-Open No. 6-274646 (hereinafter referred to as Conventional Example 1). 2. Description of the Related Art A Z-value coordinate conversion circuit (hereinafter referred to as Conventional Example 2) disclosed in Japanese Patent Application Laid-Open No. 9-115003 is known.

[0004]

In the first prior art, attribute data is written to the frame buffer by using a Z buffer which becomes unnecessary after the hidden surface erasing process is completed as a frame buffer. However, when an image in which only the attribute data is changed is to be displayed separately, there is a problem that the frame buffer must be used again as a Z buffer and the erased Z value must be written.

[0005] Conventional Example 2 attempts to reduce the amount of data stored in the Z buffer by using a coordinate system in which the depth information converted into the Z buffer is not equally spaced, thereby reducing the capacity of the Z buffer. Things. This technique utilizes characteristics (perspectiveness) when a human looks at an object. However, since the entire image is displayed in such a form, there is a problem that the appearance of the depth is actually different depending on the distance from the display device, that is, the accuracy of the depth display is deteriorated.

On the other hand, human vision has a characteristic that, when a narrow part is stared, the depth of the part can be determined finely. On the other hand, when viewing a relatively wide portion as a whole, there is a characteristic that it is difficult to determine the depth precisely. This also applies to the display of three-dimensional images by computer graphics.

The present invention provides a three-dimensional image processing apparatus and method capable of preparing a Z-buffer having a sufficient depth and displaying a required three-dimensional image even if the memory capacity of the Z-buffer is not sufficient. The purpose is to:

The present invention also provides a three-dimensional image processing apparatus and method which utilizes the above-described human visual characteristics, and can change the depth accuracy of a three-dimensional image displayed as necessary. The purpose is to do.

[0009]

In order to achieve the first object, a three-dimensional image processing apparatus according to a first aspect of the present invention provides a three-dimensional image processing apparatus in which depth information of a three-dimensional image is defined by Z-value data. A three-dimensional image processing apparatus for processing a three-dimensional image displayed by a buffer method, wherein an area for displaying a three-dimensional image is set within a capacity of a Z buffer, and a Z value in the set area is set. Only data is written in the Z buffer.

In order to achieve the first object, a three-dimensional image processing apparatus according to a second aspect of the present invention is required to display a three-dimensional image by performing hidden surface removal processing on a two-dimensional image. Setting means for setting an area for displaying a three-dimensional image obtained by performing hidden surface removal processing on the two-dimensional image within a range of a memory area capable of securing a Z buffer into which the Z value data is written; Z buffer securing means for securing a Z buffer in the memory area according to the area set in the setting means, and Z value data for each pixel indicating the depth of the three-dimensional image are stored in the area set in the setting means. Determining means for determining whether or not the data is in the area, and writing the Z value data determined to be in the area by the determining means in the Z buffer secured by the Z buffer securing means. Characterized in that it comprises a stage, a.

In the three-dimensional image processing apparatus according to the first and second aspects, an area for displaying a three-dimensional image is set in accordance with the capacity of (the area that can be secured as) the Z buffer. For this reason, even if there is no Z-buffer area (which can be secured) for displaying a three-dimensional image with sufficient depth accuracy in the entire display device for displaying an image, the set area has a fine depth accuracy. Can be displayed.

In the three-dimensional image processing apparatus according to the second aspect, the setting means includes means for setting the number of bits of the Z value data for each pixel, and the number of bits set by the means and the Z buffer. The area for displaying the three-dimensional image may be set within a range of the memory capacity that can secure the three-dimensional image.

In this case, even with the same Z-buffer capacity, a three-dimensional image can be displayed with fine depth accuracy by narrowing the set area. On the other hand, if the depth accuracy is reduced, a three-dimensional image can be displayed over a wide range. For this reason, when performing partial viewing, the depth of the displayed image can be determined finely. On the other hand, when viewing the entire image, the entire image can be displayed three-dimensionally.
In the case of this general vision, since accurate distinction cannot be made due to the visual characteristics, there is no particular problem even if the depth accuracy becomes coarse.

In order to achieve the second object, a three-dimensional image processing apparatus according to a third aspect of the present invention is required to display a three-dimensional image by performing hidden surface elimination processing on a two-dimensional image. Setting means for setting the number of bits for each pixel of the Z buffer within a range of a memory area capable of securing a Z buffer into which the Z value data is written, and Z setting according to the bit number set in the setting means. Z buffer securing means for securing a buffer in the memory area, and converting means for converting Z value data indicating the depth of the three-dimensional image supplied from the outside into Z value data having the number of bits set in the setting means And converting the Z value data converted by the conversion means into the Z buffer secured by the Z buffer securing means.
Writing means for writing to the buffer.

The three-dimensional image processing apparatus according to the third aspect requires a large capacity in the Z buffer when fine depth accuracy is required. However, when fine depth accuracy is not required, a large capacity is not required for the Z buffer, so that the memory area can be used for other purposes.

To achieve the first object, a three-dimensional image processing method according to a fourth aspect of the present invention is directed to a three-dimensional image processing method using a Z-buffer method in which depth information of a three-dimensional image is defined by Z-value data. A first setting step of setting an area for displaying a three-dimensional image in accordance with the capacity of a Z buffer; and an externally supplied Z value data set in the first setting step. A judging step of judging whether or not the object is within the area; and
Writing a value data into the Z buffer;
It is characterized by including.

In the three-dimensional image processing method according to the fourth aspect, an area for displaying a three-dimensional image is set according to the capacity of the Z buffer. For this reason, even if there is no Z-buffer area for displaying a three-dimensional image with sufficient depth accuracy in the entire display device for displaying an image, the set area contains a three-dimensional image with fine depth accuracy. Can be displayed.

The three-dimensional image processing method may further include a second setting step of setting the number of bits for each pixel of the Z buffer. In this case, the writing step may convert the Z-value data into the Z-value data having the number of bits set in the second setting step and write the Z-value data into the Z buffer.

In this case, even with the same Z-buffer capacity, a three-dimensional image can be displayed with a fine depth accuracy by narrowing the set area. On the other hand, if the depth accuracy is reduced, a three-dimensional image can be displayed over a wide range. For this reason, when performing partial viewing, the depth of the displayed image can be determined finely. On the other hand, when viewing the entire image, the entire image can be displayed three-dimensionally.
In the case of this general vision, since accurate distinction cannot be made due to the visual characteristics, there is no particular problem even if the depth accuracy becomes coarse.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In this embodiment, Z is set in the off-screen area of the frame buffer (the area of the frame buffer where the two-dimensional image is not
A case where a buffer is secured will be described as an example.

FIG. 1 is a block diagram showing a configuration of a three-dimensional image processing apparatus according to this embodiment. 1, the three-dimensional image processing apparatus 1 includes a system bus 10
And comprises a hidden surface processing area selection unit 2, a hidden surface processing control unit 3, a frame buffer control unit 4, a Z buffer control unit 5, memory interfaces 61 and 62, and a frame buffer 7. Have been.

A CPU 11, a main storage device 12, and an input device 13 are connected to the system bus 10. The display device 20 including a CRT or the like is connected to the memory interface 62. The three-dimensional image processing device 1 is provided in an input / output control device interposed between the system bus 10 and the display device 20.
In the three-dimensional image processing apparatus 1, pixel data, Z-value data,
Address data and setting data described later are input.

The hidden surface processing area selection section 2 has a hidden surface processing setting register 21, an address conversion section 22, and a 2D / 3D processing determination section 23. In accordance with an input from the input device 12, the hidden surface processing setting register 21 includes a starting point and an ending point of a rectangular area for performing hidden surface processing (three-dimensional image processing) supplied from the CPU 11 via the system bus 10, and a Z buffer. The depth (number of bits) of the Z value, which is the depth information within (the both are collectively referred to as setting data), is set.

The address conversion unit 22 converts an address for coordinates on the frame buffer 7 into an address on the Z buffer in accordance with the setting data set in the hidden surface processing setting register 21. The 2D / 3D processing determination unit 23 determines whether or not the area is a target of the hidden surface processing according to the setting data set in the hidden surface processing setting register 21 and the address on the Z buffer converted by the address conversion unit 22. The indicated clipping information is sent to the hidden surface processing control unit 3. Also, Z
Information about the depth of the value is also sent to the hidden surface processing control unit 3.

In response to a hidden surface processing request from the CPU 11, the hidden surface processing control unit 3 transmits the Z value data to the system bus 10.
Receive through. In accordance with the clipping information sent from the 2D / 3D processing determining unit 23, the hidden surface processing control unit 3 converts the Z value data converted according to the information on the Z value depth when it is within the target area of the hidden surface processing. To the Z-buffer controller 5. The hidden surface processing control unit 3 also performs processing of updating the image data of the two-dimensional image developed in the on-screen area of the frame buffer 7 with reference to the Z value data developed in the Z buffer.

The frame buffer controller 4 controls writing of image data of each pixel of the two-dimensional image input via the system bus 10 to the frame buffer via the memory interface 61. The Z buffer control unit 5
Frame buffer 7 via memory interface 61 for Z value data converted by hidden surface processing control unit 3
Controls writing to.

The memory interface 61 arbitrates the transfer of addresses or data between the frame buffer controller 4 and the Z buffer controller 5 and the frame buffer 7.

The frame buffer 7 stores image data corresponding to an image to be displayed on the display device. The frame buffer 7 is divided into an on-screen area (area where a two-dimensional image is developed) 71 and an off-screen area (area where a two-dimensional image is not developed) 72. When new setting data is set in the hidden surface processing setting register 21,
The off-screen area is cleared, and a Z buffer is secured in the off-screen area 72 according to the setting data.

The memory interface 62 controls data transfer from the frame buffer 7 to the display device 20. This data transfer instruction is sent from the CPU 11 via the system bus 10. The display device 20
An image is displayed according to the image data developed in the on-screen area 71 of the frame buffer 7.

Hereinafter, the operation of the three-dimensional image processing apparatus according to this embodiment will be described. In the following description, the capacity of the frame buffer 7 is assumed to be 4 MB. The image developed in the frame buffer 7 is displayed on the display device at a resolution of 1280 × 1024 dots. The image data of each pixel of the displayed image is represented by 8-bit color information. Also, the frame buffer 7
It is assumed that a two-dimensional image for two screens is developed
While the screen is being displayed, another screen is developed. After the development of the two-dimensional image is completed, the Z buffer is secured and the Z value data is developed.

The on-screen area 71 at this time is
Is 2.5 MB, and the capacity of the off-screen area 72 that can be secured as a Z buffer is 1.5 MB. Further, Z that can be set in the hidden surface processing setting register 21
The buffer depth (Z value width) is variable at 8, 16, and 32 bits. Z supplied via the system bus 10
It is assumed that the number of bits of the value data is 32 bits.

In this three-dimensional image display device, when the user inputs coordinates (0, 0) as the starting point of the rectangular area and (1279, 1023) as the ending point by using the input device 13, the setting data of the range of the area is obtained. Is the hidden surface processing setting register 2
Set to 1. At this time, 8 bits can be set as the depth of the Z buffer, and 8 bits are input from the input device 13 as the depth of the Z buffer and set in the hidden surface processing setting register 21. Then, a Z buffer is secured in the off-screen area 72, as schematically shown in FIG.

According to the set data, the address conversion unit 22 performs a predetermined address conversion, and the 2D / 3D processing determination unit 23 outputs depth data and clipping information. At this time, since all the regions are designated as the hidden surface processing regions, the hidden surface processing control unit 3 converts all the 32-bit Z value data supplied via the system bus 10 into the 8-bit Z value. Convert to data. Converted Z
The value data is written to the off-screen area 72 by the Z buffer controller 5 via the memory interface 61.

When all of the converted Z-value data is written into the secured Z buffer, the hidden surface processing control unit 3 performs hidden surface processing and updates the image data developed in the on-screen area 71. This update is performed when the image data is read from the on-screen area 71 and the Z value data at the position before the coordinate corresponding to the read image data is expanded in the Z buffer. Then, when the update of the image data for all coordinate positions is completed, the image data developed in the on-screen area 71 is sent to the display device 20 via the memory interface 62 and displayed.

Next, the user uses the input device 13 to set the coordinates (0, 0) as the start point of the rectangular area, and (1279, 7)
When 67) is input as the end point, the setting data of the range of the area is set in the hidden surface processing setting register 21. At this time, 8 or 16 bits can be set as the depth of the Z buffer. Therefore, 1 that enables fine display
Six bits are input from the input device 13 as the depth of the Z buffer and set in the hidden surface processing setting register 21. Then
As schematically shown in FIG. 3, a Z buffer is secured in the off-screen area 72.

In accordance with the set setting data, the address conversion section 22 performs predetermined address conversion, and the 2D / 3D processing determination section 23 outputs depth data and clipping information. At this time, the hidden surface processing control unit 3 sets the Z value in the rectangular area corresponding to the coordinates (0,0) to (1279,767) in the 32-bit Z value data supplied via the system bus 10. The data is converted to 16-bit Z value data. The converted Z value data is written to the off-screen area 72 by the Z buffer control unit 5 via the memory interface 61.

When all the converted Z value data is written into the secured Z buffer, the hidden surface processing control unit 3 updates the image data developed in the on-screen area 71 by performing hidden surface processing. This update is performed when the image data is read from the on-screen area 71 and the Z value data at the position before the coordinate corresponding to the read image data is expanded in the Z buffer. Then, when the update of the image data for all coordinate positions is completed, the image data developed in the on-screen area 71 is sent to the display device 20 via the memory interface 62 and displayed.

Next, the user uses the input device 13 to set the coordinates (0, 512) as the starting point of the rectangular area, and (640,
When 1023) is input as the end point, the setting data of the range of the area is set in the hidden surface processing setting register 21. At this time, any of up to 32 bits can be set as the depth of the Z buffer. Therefore, 32 bits that enable fine display are input from the input device 13 as the depth of the Z buffer and set in the hidden surface processing setting register 21. Then, as schematically shown in FIG. 4, a Z buffer is secured in the off-screen area 72.

In accordance with the set setting data, the address conversion section 22 performs predetermined address conversion, and the 2D / 3D processing determination section 23 outputs depth data and clipping information. At this time, the hidden surface processing control unit 3 sets the Z value in the rectangular area corresponding to the coordinates (0, 512) to (640, 1023) in the 32-bit Z value data supplied via the system bus 10. The data is written to the off-screen area 72 via the memory interface 61 by the Z buffer controller 5 as it is.

When all the converted Z value data is written into the secured Z buffer, the hidden surface processing control unit 3 updates the image data developed in the on-screen area 71 by performing hidden surface processing. This update is performed when the image data is read from the on-screen area 71 and the Z value data at the position before the coordinate corresponding to the read image data is expanded in the Z buffer. Then, when the update of the image data for all coordinate positions is completed, the image data developed in the on-screen area 71 is sent to the display device 20 via the memory interface 62 and displayed.

In the above processing, if the area for displaying the three-dimensional image is set to be wide, the depth of the Z-buffer is reduced, and the depth of the three-dimensional image cannot be displayed, but the area for displaying the three-dimensional image is set to be narrow. By doing so, the depth of the Z buffer is increased, and an image expressing a fine depth is displayed on the display device 20.

As described above, in the three-dimensional image processing apparatus of this embodiment, an area for displaying an image three-dimensionally (hidden surface processing area) can be set by an input from the input device. For this reason, even when the memory capacity of the Z buffer is not sufficiently large, it is possible to secure a Z buffer having a sufficient depth corresponding to a necessary area and display a three-dimensional image with a fine depth display.

Further, in the three-dimensional image processing apparatus of this embodiment, if the hidden surface processing area is set small, the accuracy of the depth of the three-dimensional image can be increased. On the other hand, even if the hidden surface processing area is set large, a three-dimensional image can be displayed if the depth accuracy is reduced. This makes it possible to display a three-dimensional image with necessary depth accuracy in accordance with the visual characteristics of the case of partially gaze and the case of full view.

In the above embodiment, the Z buffer is secured in the off-screen area 72, and its capacity is fixed according to the capacity of the rectangular area set in the hidden surface processing setting register 21. However, the present invention may be one in which a fixed area is secured in the Z buffer.

In the above embodiment, the hidden surface area is set by the start and end points of the rectangular area. However, the shape of the hidden surface area is arbitrary. For example, the hidden surface area may be a circle, and may be set by the coordinates of the center of the circle and the radius from the center.

In the above embodiment, the Z buffer is secured in the frame buffer off-screen area 72.
Then, according to the capacity of the frame buffer off-screen area 72, the hidden surface processing area and the depth bit width of the Z value are set. On the other hand, when the Z buffer can be secured by using the entire memory other than the frame buffer 7, the hidden surface processing area and / or the depth bit width of the Z value may be set. As a result, a region as required, a three-dimensional image with depth accuracy can be displayed, and a region (program region,
Data area).

[0047]

As described above, according to the present invention,
Even if the memory capacity of the Z buffer is not large enough,
It is possible to secure a Z-buffer with a sufficient depth corresponding to a necessary area and display a fine three-dimensional image of depth display.

Further, it is possible to display a three-dimensional image with necessary depth accuracy according to the visual characteristics of the case of partially gaze and the case of full view.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a three-dimensional image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a Z buffer secured in the three-dimensional image processing apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram schematically illustrating a Z buffer secured in the three-dimensional image processing apparatus according to the embodiment of the present invention;

FIG. 4 is a diagram schematically showing a Z buffer secured in the three-dimensional image processing apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 3D image processing apparatus 2 Hidden surface processing area selection part 21 Hidden surface processing setting register 22 Address conversion part 23 2D / 3D processing determination part 3 Hidden surface processing control part 4 Frame buffer control part 5 Z buffer control part 61, 62 Memory Interface 7 Frame buffer 71 On-screen area 72 Off-screen area 10 System bus 11 CPU 12 Main memory 13 Input device 20 Display device

Claims (6)

[Claims] 1. A three-dimensional image processing apparatus for processing a three-dimensional image in which depth information of a three-dimensional image is displayed by a Z-buffer method defined by Z-value data, wherein the three-dimensional image has a third order within a capacity of the Z buffer. An area for displaying the original image is set, and only the Z value data within the set area is set to the Z value.
A three-dimensional image processing device for writing in a buffer. 2. The method according to claim 1, further comprising: adding a hidden surface to the two-dimensional image to display a three-dimensional image by displaying the three-dimensional image. Setting means for setting an area for displaying a three-dimensional image obtained by performing hidden surface elimination processing on an image; and Z buffer securing means for securing a Z buffer in the memory area in accordance with the area set in the setting means. Determining means for determining whether or not the Z value data for each pixel indicating the depth of the three-dimensional image is within the area set by the setting means; and determining that the Z value data is within the area by the determining means. Done Z
A writing unit that writes value data to the Z buffer secured by the Z buffer securing unit. 3. The setting means includes means for setting the number of bits of the Z value data for each pixel, and the tertiary data within a range of the number of bits set by the means and a memory capacity capable of securing a Z buffer. The three-dimensional image processing apparatus according to claim 1, wherein an area for displaying an original image is set. 4. A Z-buffer within a capacity of a memory area capable of securing a Z-buffer in which Z-value data required for displaying a three-dimensional image by performing a hidden surface elimination process on a two-dimensional image is displayed. Setting means for setting the number of bits for each pixel, Z buffer securing means for securing a Z buffer in the memory area according to the bit number set in the setting means, and the three-dimensional image supplied from the outside Conversion means for converting the Z value data indicating the depth of the data into Z value data having the number of bits set in the setting means; and converting the Z value data converted by the conversion means into the Z value data.
Writing means for writing to the Z buffer secured by the buffer securing means. 5. A three-dimensional image processing method based on a Z-buffer method in which depth information of a three-dimensional image is defined by Z-value data, wherein an area for displaying a three-dimensional image is set according to the capacity of the Z-buffer. A setting step, a judging step of judging whether or not the Z value data supplied from the outside is in the area set in the setting step, and when it is judged in the judging step that the Z value data is in the area, A writing step of writing the Z-value data into the Z-buffer. 6. The method according to claim 1, further comprising a second setting step of setting the number of bits for each pixel of the Z buffer, wherein the writing step includes converting the Z value data to the number of bits set in the second setting step. The three-dimensional image processing method according to claim 5, wherein the data is converted into Z value data and written into the Z buffer.