JPH03286271A - Picture display device - Google Patents

Abstract

PURPOSE:To generate and display a picture having depth information by separating object data to be inputted to the group of moving object and to that of still object and write-processing picture data and depth data into a frame buffer. CONSTITUTION:Object data 101 is inputted for every frame. A picture generation circuit 102 stores picture element data which is picture generation-processed in a first frame buffer 104 and depth data corresponding to respective picture elements to a first depth buffer 108 concerning the moving object. The still object is picture-processed only when the position of a view point moves between the frames and it is stored in a second frame buffer 106 and a second depth buffer 110. A picture synthesis circuit 115 reads data stored in respective buffers and picture data having depth data near the viewpoint is selectively outputted.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to an image display device for displaying images having depth-related information such as three-dimensional computer graphics images, and in particular, to continuously generate video images by combining images.・Conventional technology related to image display devices Conventional technology When displaying three-dimensional computer graphics images, data related to the coordinates and colors of objects that make up the image, coordinate transformation, image clipping, hidden surface removal, etc. The generated image is stored in a memory called a frame buffer, and the pixel data of the stored image is read out in synchronization with the synchronization timing of an output device such as a CRT display and converted into a video signal. Although these processing methods (for example, "Computer Graphics" translated by Atsumi Imamiya, Japan Computer Association (1984)) are described in detail, there are no hidden surface removal methods (for example,
Various methods have been proposed, depending on the ease of implementation in hardware or the Z-buffer (or depth buffer).
A method called method is widely used.

Figure 4 shows an example of a conventional image display device that uses the two-buffer method to remove hidden surfaces.
01 is the object data input from an external device (not shown); 402 is image generation time 1 for generating an image from the input object data 401; 403 is the pixel data of the image generated by the image generation circuit 402; 404 is the pixel data 40
405 is the depth data generated by the image generation circuit 402 406 is the depth buffer that stores the depth data 405 407 is the pixel data read from the frame buffer 404 408 is the pixel data read from the frame buffer 404 409 is a video signal q outputted by the image output circuit 408. 410 is an output device such as a CRT display that displays the video signal.

The operation of the conventional image display device configured as described above will be explained below.Data 401 of an object constituting one frame of an image! The image generation circuit 402 converts the coordinates of the object data into the coordinate system seen from the viewpoint set for each frame based on the input object data 401. A process called clipping removes objects or parts of objects that are outside the field of view, and the final output device 410
In the case of three-dimensional computer graphics, it is converted to a coordinate system called a device coordinate system that corresponds to the display resolution of the object. In order to perform a process called hidden surface removal to remove hidden surfaces, depth-related coordinate data (hereinafter referred to as depth data) may be used in addition to normal two-dimensional coordinate data on the display screen of the output device 410. ζ in computer graphics
Generally, the coordinates on the screen are the X-Y coordinates, and the coordinates in the depth direction perpendicular to the high screen are the Z coordinates, and the LZ coordinates are set so that the closer you are to the viewpoint, the smaller the value becomes. In this paper, the LZ coordinate is assumed to be smaller as it approaches the viewpoint.Secondly, as an example of a processing method for removing hidden surfaces, the above-mentioned document "Computer Graphics Jpp.

The two-buffer method shown in 572 to 573 will be explained below. Image generation circuit 402 Gl First, the first frame buffer 404 and depth buffer 406 of each frame.
During initialization, pixel data 403 indicating the color of the background (infinity) is written to the frame buffer 404.The maximum value of the Z coordinate that can be expressed is written to the depth buffer 406 as depth data 405. signs of
For each object, the pixel data 403 corresponding to that object is calculated. At this time, each pixel data 403
Depth data 405 corresponding to is also obtained.

Image generation circuit 402ζ Determined pixel data 403
Each time, the depth data 405 stored in the position corresponding to the pixel data 403 in the depth buffer 406 is read out and compared with the obtained depth data 405. As a result of the comparison, if the stored depth data 405 is larger ( (If the immediately calculated pixel is closer to the viewpoint)
Then, write the obtained pixel data 403 to the corresponding position of the frame buffer 404, and at the same time write the obtained depth data 405 to the corresponding position of the depth buffer 406. Also, as a result of the comparison, the stored depth data 405 is better than the stored depth data 405. If the comparison results are equal, they can be included in either one of the above. When this process is completed for all objects. The pixel data 407 of the image stored in the frame buffer 404 in this way is sent to the synchronization timing of the output device 410 by the image output circuit 408. Another example of a conventional image display device is an image display that combines and displays images using a method called chromakey. Let me explain about the device.About the principle of chromakey.For example, "Broadcasting Technology Book Color Television" edited by Japan Broadcasting Corporation (1961) pp. 53
Chromakey is a special effect technique used in broadcasting, and is a method for creating a composite image by inserting one of the images taken with two cameras into the other. Another example of a conventional image display device using the principle is shown in FIG. In FIG. 5, 501 and 502 are two images that are the targets of the base, 503 is an image output circuit, and 504 is a composite image.The image composition circuit 503 receives the signals of the two input images 501 and 502. The image is stabilized by selectively switching electrically to output one of the images.

Problem to be Solved by the Invention When displaying a moving image of a three-dimensional computer graphics image, not all objects are always moving, nor is the starting point always moving. % Type between the previous frame and the current frame If the object itself is not moving and the position of the viewpoint has not changed, the processing required to generate an image for the non-moving object is the one before. However, in the conventional image display device of the first example shown in FIG. , each time a frame is input, the image is reprocessed and reproduced, and if all objects are not moving, the process becomes redundant. In the second example of the conventional image display device shown in Figure 5, the images to be synthesized do not have depth information, so the ability to always place one image in front of the other image is important. ＼Always place it at the back or α Only one of the bases could be created. For example, when the two images shown in Figure 6 (a) and (b) are base, the image shown in Figure 6 (c) The joint plate where the base could not be formed.
The present invention takes into consideration this point, since the objects in the two images cannot be seen as if they were moving backwards and forwards because the objects in the two images are intertwined with each other. It is an object of the present invention to provide an image display device that can continuously generate and display moving images of images having depth-related information without performing redundant processing.

Means for Solving the Problems In order to solve the above problems, the present invention provides two frame buffers, a first and a second frame buffer, for storing pixel data of an image, and a frame buffer for storing pixel data of an image. a first depth buffer that stores depth data for each pixel; a second depth buffer that stores depth data for each pixel of the image stored in the second frame buffer; input for each frame; The object data to be generated is classified into two groups, and the pixel data of an image generated from the object data of one group is written to the first frame buffer, and at the same time, the depth data for each pixel is written to the first depth buffer. an image generation circuit that writes pixel data of an image generated from object data of the other group to the second frame buffer, and simultaneously writes depth data for each pixel to the second depth buffer; frame buffer and the second
Read out the pixel data of the image stored in the frame buffer of the image and the depth data stored in the first depth buffer and the second depth buffer. Compare the depth data for each corresponding pixel to obtain a better viewpoint. The present invention provides an image display device characterized by comprising an image synthesis circuit that selectively outputs pixel data of pixels having closer depth data. The input object data is classified into two groups, moving objects and stationary objects, and separate images are generated for each group. Pixel data of the image generated is written into the first and second depth buffers, and depth data corresponding to the pixel data of the respective images is written into the first and second depth buffers. At this time, for a moving object, the image is regenerated every l frames, and for a stationary object, the image is regenerated only when the viewpoint has moved compared to the previous frame. If not, the pixel data stored in the frame buffer is retained without performing image generation processing for a stationary object. Next, the image synthesis circuit combines the pixel data stored in the two frame buffers and the two
Read the depth data stored in the two depth buffers. Compare the depth data for each corresponding pixel of the two images, the image generated from the moving object and the image generated from the stationary object, which is closer to the viewpoint. The pixel data of the pixel that has depth data is selected and output. Through the above, redundant processing for image generation for stationary objects can be reduced, and the depth data stored in the depth buffer can also be used. By doing so, it is possible to synthesize an image of a moving object and an image of a stationary object while taking into account the context of each object. This is a block diagram showing an embodiment. In FIG. 1, 101 is an object data input from an external device (not shown); 102 is an image generation circuit that generates an image from input object data 101;
03 and 105 are pixel data of the image generated by the image generation circuit 102. 104 and 106 are pixel data 103 and 10.
107 and 109 are depth data buffers generated by the image generation circuit 102. 108 and 10 are first and second frame buffers that store depth data 107 and 109, respectively. 11th is a pixel data readout from the first frame buffer 104; 12th is a pixel data readout from the second frame buffer 106; 13th is a depth data readout from the first depth buffer 108;
14th is the depth data read out from the 10th second depth buffer; 15th is the combined image based on the read pixel data 11th and 12th and the 13th and 14th depth data and converted into a video signal. The 16th image generation circuit is the video signal output by the 15th image synthesis circuit.
The seventeenth item is an output device such as a CRT display that displays a video signal.The operation of the image display apparatus of the present invention configured as described above will be described below.Object data 101?
Even if input every il frame, the image generation circuit 102
First, the input object data is classified into two groups: moving objects and stationary objects.For moving objects, as shown in the explanation of the conventional technology above, coordinate transformation, clipping, and hiding are performed. Perform image generation processing such as surface removal 1.1 Pixel data 10 of the generated image
3 to the first frame buffer 104! , knee Also, the depth data 107 corresponding to each pixel of the generated image is stored in the first depth buffer 108. If the position has moved, image generation processing is performed in the same way as in the case of a moving object described above.
X, the pixel data 105 of the generated image is stored in the second frame buffer 106, and the depth data 109 corresponding to each pixel of the generated image is stored in the second depth buffer 10
If the viewpoint position has not moved between the previous frame and the current frame, the second frame buffer 106 and the second depth buffer 10 are stored without performing image generation processing. The image synthesis circuit 15 stores the pixel data 11 and 12 stored in the first and second frame buffers 104 and 106, and the first and second frame buffers 104 and 106. Read the 13th and 14th depth data stored in the 10th and 2nd depth frame buffers 108, compare the 13th and 14th depth data corresponding to each pixel, and select the pixel whose depth data is closer to the viewpoint. FIG. 2 shows a block diagram of an embodiment of the image synthesizing circuit No. 15. In FIG. 2, 201 is a depth data comparison circuit, 202 is a pixel data selection section, and 203 is a pixel data output as a selection result of the selection circuit 202.
4 is a video signal No. 1 corresponding to the pixel data output device No. 17;
205 is a signal for controlling the selection circuit 202. Nak 11th to 14th are 1st
The pixel data and depth data in the figure are the same, the 16th is the same as the video signal in Figure 1, and the 17th is the same as the output device in Figure 1. Data 13 and 14 are compared for each pixel by a comparison circuit 201, and a control signal 205 is output to a selection circuit 2.2 to select the pixel data of the pixel whose depth data is closer to the viewpoint. The selection circuit 202 selects either the eleventh or the twelfth input first and second pixel data according to the instruction of the control signal 205 and outputs it to the signal conversion circuit 204.
The signal conversion circuit 204 converts the input pixel data 204 into
Next, another embodiment of the image display device of the present invention is shown in FIG. 3. In FIG. 3, 301 is a first frame buffer with a capacity capable of storing two frames of pixel data;
302 is a second frame buffer that has a capacity to store two frames of pixel data; 303 is a first depth buffer that has a capacity to store two frames' worth of depth data; 304 stores two frames' worth of depth data. A second depth buffer with a capacity of 101
to 103, 105, 107, 109, and 11th to 17th are the same as those in FIG.
For the sake of convenience, one frame of one frame will be referred to as Ai, and the other one frame will be referred to as B side. Generation circuit 1
02 transfers the generated image to the first frame buffer 301
When storing in either the first depth buffer 303 or the second frame buffer 302 or the second depth buffer 304, write one frame on either the LA side or the B side, and - combine all images. Circuit No. 15 Gi
The image generation circuit 102 reads out the pixel data and depth data stored in one frame on the side to which no writing is being performed.Input object data 101
Only when the image generation process is completed and a new image is generated, the roles of the A side and B side of each buffer 301 to 304 are switched and the process moves on to the next frame. However, if no new image is generated, If the data stored in the buffer and depth buffer are retained as they are, switching is not performed. The explanation is that the image generation process is performed for each group by completely dividing the board into two groups, moving objects and stationary objects. There is no problem even if image generation processing is performed sequentially for each individual object while determining whether the object data is moving or stationary. Hidden surface removal method GEL in the example image generation circuit It is not necessarily limited to the Z-buffer method, but other hidden surface removal methods may be used to generate pixel data and depth data (as described above, the effects of the invention are According to the present invention, when continuously generating and displaying moving images of three-dimensional computer graphics images, image generation processing for a stationary object is performed.
This process does not necessarily have to be performed every frame.The processing time required for image generation can be shortened.The effect of speeding up image generation is that

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the image display device of the present invention. FIG. 2 is a block diagram showing an embodiment of the image synthesis circuit constituting the image display device of the present invention. FIG. 4 is a block diagram showing the configuration of another embodiment of the conventional image display device. FIG. 5 is a block diagram showing the configuration of the first example of the conventional image display device. FIG. 6 is a diagram showing an example of an image for explaining the problems of the conventional image display device.
・Object data 102...image generation circuits 103, 10
5... Pixel data 107, 109... Depth data 104... jll frame buffer, 106...
2nd frame buffer, 108...first depth buffer, 10th...second depth buffer, 11th, 12th...pixel buffer 13th, 14th...depth data buffer 15...Image base cycle 1i 16th...Video signal 17th...Output device 201...Comparison same section 202...Select same section 203.
...Pixel data section 204...Signal conversion circuit section 205...
- Selection circuit control signal 301...first frame buffer, 302...second frame buffer, 303...first depth buffer, 304...second depth buffer.

Claims (4)

[Claims] (1) First and second two that store image pixel data
a first depth buffer that stores depth data for each pixel of the image stored in the first frame buffer; and a first depth buffer that stores depth data for each pixel of the image stored in the second frame buffer; A second depth buffer stores the depth data of the first frame, and the second depth buffer stores the depth data of the first frame.The second depth buffer stores the depth data of the first frame. The depth data for each pixel is written to the first depth buffer at the same time as the depth data for each pixel is written to the buffer, and the depth data for each pixel is written to the second frame buffer at the same time as the pixel data of the image generated from the object data of the other group is written. an image generation circuit that writes depth data into the second depth buffer; pixel data of an image stored in the first frame buffer and the second frame buffer; It is equipped with an image synthesis circuit that reads the depth data stored in the depth buffer, compares the depth data for each corresponding pixel, and selectively outputs the pixel data of the pixel whose depth data is closer to the viewpoint. An image display device characterized by: (2) The object data has information that identifies whether each object is a moving object or a stationary object, and the image generation circuit moves the object data that is input for each frame. The pixel data of the image generated from the object data of the moving object group is classified into two groups: moving objects and stationary objects, and at the same time the pixel data of the image generated from the object data of the moving object group is written to the first frame buffer. The depth data of each pixel is written into the first depth buffer, and the pixel data of an image generated from object data of a group of stationary objects is written into the second frame buffer, and the depth data of each pixel is written into the first depth buffer. The image display device according to claim 1, wherein the image display device writes to a second depth buffer. (3) The object data has information that identifies whether each object is a moving object or a stationary object, and the image generation circuit moves the object data that is input for each frame. The pixel data of the image generated from the object data of the moving object group is classified into two groups: moving objects and stationary objects, and the pixel data of the image generated from the object data of the moving object group is written to the first frame buffer. Depth data is written to the first depth buffer, and pixel data of an image is generated from object data of a group of objects that are stationary only when the viewpoint moves between the previous frame and the current frame. is written to the second frame buffer, and at the same time, the depth data for each pixel is written to the second depth buffer, and if the viewpoint has not moved between the previous frame and the current frame, it remains still. The pixel data of the image stored in the second frame buffer and the depth data stored in the second depth buffer are maintained as they are without generating a new image from the object data of the group of objects in the object group. Claim 1 characterized by
The image display device described. (4) The first and second two frame buffers and the first and second two depth buffers each have a capacity that can store two frames of pixel data and depth data; One of the buffers with a capacity for one frame is used exclusively for writing pixel data and depth data from the image generation circuit, and the other buffer with a capacity for one frame is used for reading pixel data and depth data to the image synthesis circuit. For exclusive use, 1
The write-only side buffer and the read-only side buffer are switched only when a new image is generated for each frame, and the write-only side buffer and the read-only side buffer are switched when no new image is generated. The image display device according to claim 1, wherein the image display device is used without switching.