JPS63184882A - Stereoscopic image display method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a stereoscopic image display method that calculates the brightness of polygons according to a scan line algorithm of three-dimensional computer graphics.

[Conventional technology]

As a conventional stereoscopic image display method, when calculating the brightness of a polygon according to the scan line algorithm of three-dimensional computer graphics, the brightness of each vertex of the polygon is first calculated, and then the inside is interpolated by shading. It is common to adopt °ζ.

[Problem that the invention seeks to solve]

However, the conventional stereoscopic image display method described above has various problems depending on the selection of the number of polygon divisions. That is, when a curved surface is approximated by polygons, each polygon has a different normal vector, so it must be divided into relatively fine polygons, but a particular problem is the number of plane divisions. If it is a plane, the normal vectors of the divided polygons are all equal, but depending on the number of divisions, the following problems arise.

(1) When the number of divisions is small: When the light source is close to the polygon P as shown in Figure 7(a), or when the viewpoint V is close to the polygon P as shown in Figures 7~), If there is a sudden change in brightness at the reflection point R, it is impossible to perform accurate brightness calculations.

(2) When the number of divisions is large The greater the number of divisions, the more accurate brightness calculation becomes possible, but simply increasing the number of divisions requires a huge data area and increases the amount of calculation. do.

Therefore, the present invention has been made by focusing on the problems of the above-mentioned conventional example, and by making it possible to appropriately control the number of polygon divisions depending on the situation, the present invention solves the problems of the above-mentioned conventional example The purpose of this invention is to provide a stereoscopic image display method that can solve the problem.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a three-dimensional image display method in which brightness calculation of polygons is performed according to a scan line algorithm of three-dimensional computer graphics. When calculating the vertex brightness, the subdivision processing means sets a sample point inside the polygon, compares the brightness obtained by shading of the sample point with the actual brightness, and only when the brightness change is large, the sample point is set inside the polygon at the sample point. It is characterized in that a subdivision process is performed to subdivide the polygon, and each of the subdivided polygons is processed again by the subdivision processing means.

[Effect]

In this invention, when calculating the vertex brightness, sample points are provided inside each polygon by the subdivision processing means, and the brightness obtained by shading from the vertex brightness at this sample point is compared with the actual brightness, and the brightness change is large. For example, when the absolute value of the difference between the shading brightness and the actual brightness exceeds a certain darkness value, the polygon is divided at that sample point. Furthermore, by repeating the same process for the divided polygons and dividing only the portions where the brightness changes are large into finer polygons, the number of polygon divisions can be controlled depending on the situation.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the figure, l is an information input device for inputting primitive information such as vertex coordinates of primitives consisting only of planes, and the primitive information input by this information input device l is input to the image processing device 2. This image processing device 2
Stereoscopic image processing is performed at , and the processing results are output to the rusk scan type CRT display 3 and displayed on its display screen.

The image processing device 2 has at least an interface 2a, an arithmetic processing device 2b, and a storage device 2c, and when primitive information representing a solid is input from the information input device 1, the arithmetic processing device 2b performs subdivision as shown in FIG. Execute processing.

That is, in step (2), the normal vector of each polygon constituting the primitive is calculated based on the primitive information.

Next, the process moves to step (2), where each polygon is divided into triangular polygons according to its size, shape, etc., and the addresses CXa, Ys of their vertex coordinates are obtained.

ZA), (Xs, Ys, Z*) and (Xc, Yc,
Zc) is calculated and stored in a predetermined storage area of the storage device 2C as polygon information.

Next, the process proceeds to step (2), where the brightness of each vertex of the divided polygon is calculated and stored together with its address in the primary storage block Bl formed in a predetermined storage area of the storage device 2c.

Next, the process proceeds to step (2), where the variable n is set to "l", and the process proceeds to step (2).

In this step (2), if the triangular polygon stored in the n-th storage block is ΔABC, and its apex luminances are LA, Ll, and LC, the shading luminance at the center of gravity G of ΔABC, that is, the sample point, calculated by glow shading. t and a are calculated according to the following formula (1).

Le = (ta +Ll +Lc) ””””
``''(1) Next, proceed to step 2, and when the actual brightness at the center of gravity G is , /, the difference value between this actual brightness, ,' and the shading brightness by glow shading calculated in step 2, is calculated. The absolute value of ILllLG'l
It is determined whether or not exceeds a preset threshold T. When the judgment result is It,5-LG'l>T, it is judged that the brightness change is large, and the process moves to step Triangle (ΔGAB, ΔGBG, ΔGC
A), the information is stored in the n+1 storage block 87.1 formed in a predetermined storage area of the storage device 2c, and then the process proceeds to step (2), and the determination result is Its-t.
, e'l≦T, it is determined that the luminance change is small and the process directly proceeds to step (2).

In step ■, it is determined whether or not the processing of steps ■ to ■ has been completed for all the triangles stored in the primary storage block B1, and if the processing has not been completed, the process returns to step ■. , When the processing is completed, the process moves to step (3).

In this step ■, the n+1st storage block B,...
Determine whether triangle data is stored in I, and if triangle data is stored, step [phase]
, set the variable n to n+1, and then repeat step ■
Returning to step 1, if no triangle data is stored, the process moves to step (3), where each divided triangle is filled with shading, and the process is completed.

Here, the processing of steps Φ to (2) above corresponds to the subdivision processing means.

Next, the operation of the above embodiment will be explained with reference to FIGS. 3 to 5.

First, polygon information representing the vertex address of each polygon constituting a primitive is created using primitive information input from the information input device 1 and stored in the primitive information storage area PR formed in the storage device 2C. As shown in FIG. 5, the polygon information is stored in the polygon information storage area po formed in the storage device f2c, and
Calculate the normal vector for each polygon (step ■).

Next, if one polygon 5 has a complicated shape as shown in FIG. 3(a), this polygon 5 is divided into a divisible number of triangles as shown in FIG. 6, and the vertices of each divided triangle 6 are A, B, and C, and each vertex address (
Xa, Ya, Za), (XL Yl+ Z++
), (Xc, Yc, Zc) are calculated. In this case, even if the polygon 5 is a triangle as shown in Figure 4(a), if its area is large, it can be divided into triangles 6 by dividing it by line segments connecting the midpoints of each month as shown in Figure 4 (in Figure 4). To divide.

Next, the vertex brightness LA+Lm of each divided triangle 6,
Lc is calculated by a scanning algorithm, and these are converted into their vertex addresses (Xa, yA, za), (xm.

yl, Zs) and (Xc, Yc, Zc) in the primary storage block B+ formed in the storage device 2C as shown in FIG.

Next, as shown in FIG. 6(a), the primary storage block B
The data of each triangle 6 stored in + is read out, and the shading brightness L- at the center of gravity G, which is a sample point in the triangle shown in FIG.

Next, the absolute value ILG-t,,'l of the difference value between the calculated shading luminance L and the actual luminance L6' at the center of gravity G is calculated.
Determine whether or not exceeds a preset threshold T,
If it exceeds (l LG - LG '1>T),
Judging that the luminance change is large, the triangle is divided into 3 parts by line segments connecting the center of gravity G and each vertex, as shown in Figure 6 (C), and three triangles (ΔGAB, ΔGBC, ΔGCA) are created.
), and the vertex addresses and vertex brightness of these three triangles are stored in the secondary storage block B2 formed in the storage device 2c as shown in FIG. 6(d), and then the primary storage block It is determined whether the comparison judgment of the shading brightness L and the actual brightness LG' has been completed for all the triangles stored in B1, and if there is an unprocessed triangle, the shading brightness and the actual brightness are compared. Make comparative judgments.

Further, as a result of comparing and judging the shading luminance L6 and the actual luminance RI,', if ILs-ts'l≦T, it is determined that the luminance change is small and is stored in the \ ゛ primary storage block B. It is determined whether or not the comparison judgment of the shading luminance Ls and the actual luminance L6' has been completed for all the triangles that have been processed, and if there is an unprocessed triangle, the shading luminance and the actual luminance are compared and determined for this triangle. .

Then, for each triangle stored in the primary storage block B1, the shading brightness L6 and the actual brightness are
When the comparison and judgment of
It is determined whether the apex address and vertex brightness of the triangle are stored in block 8, and if they are stored, a comparison judgment process similar to that for the primary storage block B is performed, and this is Repeat up to the primary storage block B. Then, when there is a primary storage block B1 in which the vertex address and vertex brightness of the triangle are not stored, each polygon divided during this time is filled with predetermined shading. and complete the subdivision process.

By doing this, only the parts of the polygon where the brightness changes are large are subdivided, so clear image processing can be performed even with a small number of divisions, and the polygon data capacity can be significantly reduced. Processing speed can be improved.

In the above embodiment, a case has been described in which a sample point within a polygon is used as the center of gravity, but the present invention is not limited to this, and it goes without saying that any other arbitrary point can be used as the sample point.

Furthermore, shading is not limited to glow shading, and other shading may be applied.

〔Effect of the invention〕

As explained above, according to the present invention, the number of polygon divisions is automatically controlled according to changes in brightness, so the number of polygon divisions required to generate a realistic image using the conventional method is reduced. As a result of being able to reduce the number compared to the number of data, it is possible to reduce the memory area for data and also to improve the processing speed for all the data.

In addition, if you divide polygons by determining brightness changes using a threshold value, as in clay figurines, you can make the threshold thicker (by doing so, the number of divisions will be reduced and faster screen processing can be performed; By making the size smaller, parts with large brightness changes are divided into smaller parts, so it is possible to generate a three-dimensional image based on accurate brightness calculation, which has the advantage of making it possible to create a three-dimensional image according to the situation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a flowchart showing an example of the subdivision processing procedure.
Figures (a), (b) and Figure 4 (a) and crest) are explanatory diagrams showing the polygon shape and its subdivision state, respectively.
The figure is an explanatory diagram showing the flow of information for each storage block.
The figure is an explanatory diagram of a division processing procedure to provide a detailed explanation of the present invention, and FIGS. 7(a) and 7) are explanatory diagrams showing the relationship between viewpoints and light sources for polygons, respectively. In the figure, l is an information input device, 2 is an image processing device, 2a is an interface, 2b is an arithmetic processing device, 2C is a storage device,
3 is a rask scan type CRT display, PR is a primitive information storage area, PO is a polygon information storage area, B1 to B are storage blocks, 5 is a polygon, and 6 is a triangle.

Claims (2)

[Claims] (1) In a stereoscopic image display method that calculates the brightness of a polygon according to the scan line algorithm of three-dimensional computer graphics, when calculating the brightness of the vertex of the polygon, sample points are set inside the polygon by a subdivision processing means. , compare the brightness obtained by shading of the sample point and the actual brightness, and only when the brightness change is large, perform subdivision processing to subdivide the polygon at the sample point, and re-divide each subdivided polygon. A stereoscopic image display method characterized by processing by a subdivision processing means. (2) The stereoscopic image display method according to claim 1, wherein the polygon is a triangle, and the center of gravity thereof is used as a sample point.