JP2000057372A - Image processor, image processing method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a more natural image even by a computer system which is comparatively inexpensive and structured with restricted operation speed. SOLUTION: An image processor is provided with a three-dimensional shape storage part 15 to store three-dimensional shape information with normal information on all vertexes, an image storage part 16 for mirror reflection effect to store an image for mirror reflection effect corresponding to the shape of a light source, an input part 14 to specify a position of the three-dimensional shape in the entire space, a position of a viewpoint, a position of the light source in the entire space and a mirror reflection coefficient of the three-dimensional shape and a three-dimensional image generating means to generate a display image of the three-dimensional shape by calculating a sticking position of the image for mirror reflection effect corresponding to the vertexes from the normal information of the vertexes of the three-dimensional shape, the position of the three-dimensional shape in the entire space, the position of the viewpoint, the position of the light source and the mirror reflection coefficient and performing perspective projection of the three-dimensional shape on which the image for mirror reflection effect is stuck according to the sticking position of the image for mirror reflection effect which is calculated for each vertex on a projection plane according to the position of the viewpoint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, a pixel processing method, and a storage medium applied to, for example, a personal computer and a video game machine.

[0002]

2. Description of the Related Art Recently, computer graphics have been widely used, and methods for expressing more realistic images without imposing a burden on hardware and software are being developed every day.

[0003] In computer graphics technology used in relatively inexpensive systems such as personal computers and video game machines, shadow calculation simulates only diffuse reflection, which is called Gouraud shading. Many only support features.

[0004]

For the above-mentioned shadow calculation, instead of the Gouraud shading, a specular reflection is called in accordance with a viewpoint position and a light source position, which is called Phong shading.
There are some that support functions that enable more natural depiction.

[0005] However, the von shading requires a much larger amount of calculation than the Gouraud shading, so that a personal computer or a video game in which moving image processing must be performed with an inexpensive system configuration. It was difficult to perform on machines.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to produce a more natural image even in a computer system having a relatively inexpensive configuration with a limited calculation speed. An image processing device that can be obtained,
An object of the present invention is to provide an image processing method and a storage medium.

[0007]

According to the first aspect of the present invention,
First storage means for storing three-dimensional shape information having normal information of all vertices, second storage means for storing a specular reflection effect image corresponding to the shape of the light source, and the entirety of the three-dimensional shape First designating means for designating a position in a space, second designating means for designating a viewpoint position and a light source position in the whole space, and third designating means for designating a specular reflection coefficient of the three-dimensional shape. A paste position calculation for calculating a paste position of a specular reflection effect image corresponding to the vertex from the normal line information of the vertex of the three-dimensional shape, the position in the whole space, the viewpoint position and the light source position, and the specular reflection coefficient. Means, and a three-dimensional shape in which the specular reflection effect image is pasted in accordance with the pasting position of the specular reflection effect image calculated for each vertex constituting the three-dimensional shape, is projected onto a projection plane in accordance with the viewpoint position. By viewing the projection, characterized by comprising an image producing means for producing a display image of the three-dimensional shape.

With this configuration, even a computer system having only a Gouraud shading function and having a relatively inexpensive configuration with a limited calculation speed can be used.
It is possible to obtain a more natural image with a specular reflection effect.

According to a second aspect of the present invention, in the first aspect of the present invention, the image generating means according to the pasting position of the specular reflection effect image calculated for each vertex constituting the three-dimensional shape. The mirror reflection effect image and the image pattern stored in advance are superimposed and pasted.

With this configuration, in addition to the operation of the first aspect of the present invention, the image for the specular reflection effect and the image of the texture pattern are superimposed and pasted.
Further, a natural and realistic image can be obtained.

According to a third aspect of the present invention, there is provided a first storage process for storing three-dimensional shape information having normal information of all vertices, and a second storage process for storing an image for a mirror reflection effect corresponding to the shape of a light source. Storage processing, a first specification processing for specifying a position of the three-dimensional shape in the entire space, a second specification processing for specifying a viewpoint position and a light source position in the whole space, and a mirror surface of the three-dimensional shape A third specifying process for specifying a reflection coefficient, and a specular reflection effect corresponding to the vertex from the normal line information of the vertex of the three-dimensional shape, the position in the whole space, the viewpoint position and the light source position, and the specular reflection coefficient. Paste position calculation processing for calculating the paste position of the image for use;
The three-dimensional shape, in which the specular reflection effect image is pasted according to the pasting position of the specular reflection effect image calculated for each of the vertices constituting the three-dimensional shape, is perspectively projected on a projection plane in accordance with the viewpoint position. Image generation processing for generating a display image having a two-dimensional shape.

According to this method, even a computer system having only a Gouraud shading function and having a relatively inexpensive configuration with a limited operation speed can be used.
It is possible to draw a more natural image with the mirror reflection effect.

According to a fourth aspect of the present invention, there is provided a first storage step of storing three-dimensional shape information having normal information of all vertices, and a second storage step of storing an image for a mirror reflection effect corresponding to the shape of a light source. , A first designation step of designating the position of the three-dimensional shape in the whole space, a second designation step of designating a viewpoint position and a light source position in the whole space, and a mirror surface of the three-dimensional shape A third specifying step of specifying a reflection coefficient, and a specular reflection effect corresponding to the vertex from the normal line information of the vertex of the three-dimensional shape, the position in the entire space, the viewpoint position and the light source position, and the specular reflection coefficient. A pasting position calculating step of calculating a pasting position of the image for use;
The three-dimensional shape, in which the specular reflection effect image is pasted according to the pasting position of the specular reflection effect image calculated for each of the vertices constituting the three-dimensional shape, is perspectively projected on a projection plane in accordance with the viewpoint position. A computer program for executing an image generation step of generating a display image of a dimensional shape is stored.

With such stored contents, Gouraud
Even a relatively inexpensive computer system having only a shading function and having a limited operation speed can draw a more natural image with the mirror reflection effect.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the circuit configuration, and reference numeral 11 denotes an arithmetic processing unit including a CPU that controls the overall operation. A storage unit 12, a main memory 13, an input unit 14, a three-dimensional shape storage unit 15, an image storage unit 16 for specular reflection effect, and a three-dimensional image generation unit 17 are connected to the arithmetic processing unit 11 via a bus B. You.

The storage section 12 has a removable storage medium 12a storing an operation program of the arithmetic processing section 11, and a main memory 13 stores a part of the operation program and processing data when executing the image generation processing. Store temporarily.

The input unit 14 includes a keyboard and a mouse for receiving input from an operator and its controller, a communication circuit for receiving input from another computer system, and three-dimensional shape data to be processed and image data to be a texture pattern. The input data is sent to the arithmetic processing unit 11.

The three-dimensional shape storage unit 15 is constituted by a memory, and temporarily stores the input three-dimensional shape data to be processed and supplies the data to the arithmetic processing unit 11. The specular reflection effect image storage unit 16 is configured by a memory, and temporarily stores the input image data for the specular reflection effect to be processed and supplies the image data to the arithmetic processing unit 11.

The three-dimensional image generation unit 17 includes a texture image storage unit 18 which is a memory for temporarily storing the image data of the texture pattern sent from the input unit 14 before the start of the rendering process, and a CRT and its driver, for example. Is connected, a rendering process is executed in accordance with an instruction from the arithmetic processing unit 11, and a three-dimensional computer graphics image is generated and displayed on the display unit 19. Here, for example, a personal computer Use the graphics accelerator with Gouraud shading function provided for

By using this graphics accelerator, the display color of each vertex of a two-dimensional polygon obtained by projecting a polygon constituting a three-dimensional shape onto a projection plane can be determined. The display color of each pixel inside the polygon can be determined by interpolating the display color of the vertex of the polygon.

However, when texture mapping is performed on a three-dimensional polygon using the graphics accelerator, the image data of the texture pattern to be pasted and the coordinate values on the image of the texture pattern corresponding to each vertex of the polygon, ie, the pasting position Is specified, the pasting position of the texture pattern to the vertex is interpolated for each pixel inside the two-dimensional polygon on the projection plane, and the pasting position of the texture to the pixel is obtained.

Then, the display color of the texture-mapped polygon pixel is determined from the texel value of the texture pattern corresponding to the pasting position and the display color of the pixel. Note that, depending on the type of the graphics accelerator constituting the three-dimensional image generation unit 17, the calculation for the display color of the pixel and the texel value is performed.
It is good also as what can be arbitrarily selected from several kinds prepared beforehand.

Next, the operation of the above embodiment will be described. FIG. 2 mainly shows a series of processing procedures until a three-dimensional image subjected to a specular reflection effect is displayed by the arithmetic processing unit 11, and at the beginning, the arithmetic processing unit 11
The three-dimensional shape data created by the three-dimensional register creation system is input from the input unit 14 and stored in the three-dimensional shape storage unit 15 (step S1).

Here, the three-dimensional shape data handled includes the following elements: (a) the vertex coordinate values of the polygons forming the three-dimensional shape; (b) the normal vectors (c) of the vertices of the polygons forming the three-dimensional shape. ) Has at least the display color of the polygon forming the three-dimensional shape, and furthermore, when texture mapping is performed on the polygon, the following elements are used: (d) the texture mapped to the polygon forming the three-dimensional shape. Texture ID (e) A pasting position of a texture image to a vertex of a polygon constituting a three-dimensional shape is also required. However, when performing texture mapping, in addition to storing the above-described three-dimensional shape data in the three-dimensional shape storage unit 15, the arithmetic processing unit 11 causes the image of the texture pattern created by another three-dimensional register creation system to be generated. It is necessary to take in data from the input unit 14 and store it in the texture image storage unit 18 via the three-dimensional image generation unit 17.

Next, the arithmetic processing unit 11 takes in the specular reflection effect image created by the other image creating system from the input unit 14, and through the three-dimensional image creating unit 17, in step S 1, the texture image storage unit 18. In addition to the image data of the texture pattern stored in (1), the image data is also stored and held as image data of the texture pattern (step S2).

FIG. 3 shows the texture image storage unit 1 at this time.
8 exemplifies an image for a specular reflection effect stored in 8
Here, a point light source is shown that is created such that the central part is brightest and gradually darkens toward the peripheral part. The attenuation of the brightness is set so as to change in accordance with the curve of the cosine wave, and is created as a black-and-white grayscale image in which “white” is “1” and “black” is “0”. Thus, "0 (black)" is set for all areas that are at least a predetermined distance from the center position.

Thereafter, the position of the three-dimensional shape to be displayed in the whole space is designated by inputting with a keyboard, a mouse or the like of the input unit 14 (step S3).
At this time, it is necessary to specify and input not only the position of the three-dimensional shape in the entire space but also the direction of the three-dimensional shape, that is, which direction the front faces.

Next, in order to create a three-dimensional computer graphics image, viewpoint information and light source information are designated and input by the input unit 14 (step S4). That is, the three-dimensional computer graphics image is an image obtained when the target three-dimensional shape is observed from a predetermined viewpoint, and a three-dimensional computer graphics image cannot be generated unless viewpoint information is clarified. Because.

Here, the viewpoint information is composed of three pieces of information: the position of the viewpoint in the whole space, the direction of the line of sight depending on the direction of the line of sight, and the viewing angle. Of these, the viewing angle corresponds to the angle of view of the camera lens. If the viewing angle is narrow like a telephoto lens, only a narrow range can be observed, but a distant shape can be displayed large. Conversely, if the viewing angle is wide, as in a wide-angle lens, a wide range can be observed, but the drawing of individual shapes in the viewing field will be small. Therefore,
What is important is that the three-dimensional shape to be observed does not deviate from the visual field when the viewpoint information is specified.

In the present embodiment, a parallel light source or the above-described FIG. 3 is used as a graphics accelerator for a personal computer constituting the three-dimensional image generation unit 17.
As shown in the example of the image for the specular reflection effect, only the point light source is targeted, and the light source direction (parallel light source) is used as the light source information.
Alternatively, three pieces of information of the light source position (point light source), the brightness of the light source, and the color of the light source are input and designated.

Here, in the case of a parallel light source, the intensity of light from the light source received by the three-dimensional shape is constant, but in the case of a point light source, the light intensity decreases as the distance from the light source increases. Becomes

Next, the specular reflectance and the specular reflection coefficient are input by the input unit 14 (step S5). This is because when considering a three-dimensional shape that causes specular reflection, the appearance of highlights generated by specular reflection differs depending on the physical characteristics of the surface, and the mirror surface is used as a parameter representing the physical characteristics of the surface of the three-dimensional shape. This is because there is a reflectance and a specular reflection coefficient.

The specular reflectance is a parameter indicating how much of the intensity of light incident on the surface of the object is reflected, and the surface reflection coefficient is how the highlight light generated on the surface is spread. Is a parameter representing

When highlights occur in a wide range, the specular reflection coefficient is small, and when highlights occur only in a narrow range, the specular reflection coefficient is large. Normally, a surface having a smooth texture such as a metal surface has both a large specular reflectance and a large specular reflection coefficient, and a surface having a rough texture has both a small specular reflectance and a small specular reflection coefficient.

The specular reflectance and the specular reflection coefficient may not be input from the input unit 14 but may be added in advance as a part of the three-dimensional shape data. Since the input and designation of various data and information have been completed, the arithmetic processing unit 11 instructs the three-dimensional image generation unit 17 to perform specular reflection corresponding to each vertex of the three-dimensional surface polygon. The sticking position on the effect image is calculated (step S6).

Hereinafter, a method of calculating the sticking position will be described. As shown in FIG. 4, a normal vector N is given to each vertex of the surface polygon in advance. A viewpoint direction vector V given from the vertex to the viewpoint direction is obtained. next,
A reflection direction vector R forming the same angle as the angle θ between the normal vector N and the viewpoint direction vector V with respect to the normal vector N
Ask for. Here, it is assumed that the normal vector N, the viewpoint direction vector V, and the reflection direction vector R are on the same plane. If these three vectors are unit vectors,
The reflection direction vector R can be obtained by the following equation.
That is, R = 2 ^* (cos (θ) ^* N−V) + V = 2 ^* (N · V) ^{* −} V (1) (However, (N · V): inner product of vectors N and V.) Therefore, the smaller the angle δ between the reflection direction vector R and the light source direction vector L, the greater the effect of specular reflection.

Next, consider a light source direction coordinate system in which the light source direction vector L is the Z-axis direction as shown in FIG. Considering the unit vectors Lx, Ly, and Lz of the global coordinate system corresponding to the respective coordinate axes of the light source direction coordinate system, the unit vector Lz in the Z-axis direction is equivalent to the light source direction vector L.
Here, the unit vector Y in the Y-axis direction of the global coordinate system is
[0,1,0], Lx = | (Y × L) |, Ly = (L × Lx), Lz = L (2) (where (Y × L): the outer product of Y and L, | V |: a unit vector of V.) The following matrix Lm, that is,

[0038]

(Equation 1) Assuming that the reflection direction vector on the light source direction coordinate system corresponding to the reflection direction vector R in the overall coordinate system is Rl, it is clear that the reflection direction vector R and the vector Rl have the following relationship. That is, R = Lm ^* Rl (4) Therefore, the vector Rl is obtained by the following equation. That is, Rl = Lm- ^{1 *} R (5) The polar coordinate value (α, β) of the vector Rl can be obtained by the following equation. That is,

[0039]

(Equation 2)

Therefore, the sticking position T = [s, t] of the vertex on the specular reflection effect image can be represented by a function of the polar coordinate value and the specular reflection coefficient n as shown in FIG. That is, s = f (α, n), t = f (β, n) (8) The brightness becomes “0” from the center of the specular reflection effect image, that is, the position of “1” where the brightness is the highest. Distance to le
Assuming ngth, the specular reflection coefficient k is determined by the following equation. That is, k = length ^* 2 / π (9) The function f (X, n) of the above equation (8) is given by the following equation. That is, f (X, n) = cos ^-1 (cos ⁿ (X)) (10) However, a graphics accelerator for a personal computer that needs to process the above equations (7) and (10) in real time If the calculation is performed by using, the amount of calculation becomes enormous compared to the calculation speed, and it cannot be processed very much. Therefore, the approximate expression is usually used to reduce the amount of calculation.

In this way, the pasting position of the vertex of the surface polygon with respect to the specular reflection effect image can be obtained by the above-described method. Next, the three-dimensional image generation unit 17
Creates a three-dimensional display image to which a mirror reflection effect has been applied (step S7).

At this time, first, a surface polygon to be drawn based on the viewpoint information is projected on a projection plane, and the following operation is performed on the projected surface polygon. First, the reflected light intensity of each vertex of the display polygon is obtained. At this time, the reflected light of the object due to the ambient light and the diffuse reflection follows the Lambert model, and the reflected light I at the vertex of the surface polygon is given by the following equation. That is, Id = Ia ^* ka + Il ^* kd · cos ((L · N)) (11) (where Ia: ambient light intensity, ka: converted reflection coefficient of ambient light, Il: incident light intensity, kd: Diffuse reflectance.) The thus obtained reflected light becomes the display color of the object. In the surface polygon, the magnitude of the reflected light at each vertex has a different value because the normal vector of the vertex is different. Since the three-dimensional image generation unit 17 has a Gouraud shading function, when rendering a surface polygon, it is necessary to interpolate the display color of the pixels inside the polygon and the reflected light intensity of the vertices constituting the polygon. And calculate the value as Id
Let p.

The pasting position of the specular reflection effect image corresponding to the pixel can also be obtained by interpolating the pasting position of each vertex. Here, the value of the texel of the image for specular reflection effect corresponding to the pasting position is Tsp.
Then, the display color Ip of the pixel is determined by the following equation. That is, Ip = Idp + Il ^* ks ^* Tsp (12) (where ks is the specular reflectance) Since the incident light intensity Il and the specular reflectance ks in this equation (12) are known in advance, the product is calculated. If so, the calculation can be performed by the three-dimensional image generation unit 17.

Further, when a texture pattern is attached to the surface polygon, it is necessary to take the value of the texture pattern into consideration. In this case, the pasting position of the texture pattern to the surface polygon is given in advance, and the pasting position for the pixel can be obtained by interpolating the pasting position of the vertex. Therefore, assuming that the value of the texel corresponding to the pixel is Tp, the display color Ip of the pixel can be obtained by the following colors. That is, Ip = Idp ^* Tp + Il ^* ks ^* Tsp (13) By performing this procedure for all the pixels constituting the surface polygon, the projected surface polygon can be colored with the mirror reflection effect. It becomes something.

The image data of the surface polygon colored by applying the specular reflection effect is sent to the display unit 19, stored in an image storage memory called a frame buffer, and displayed and output (step S8).

By sequentially executing the above processing procedures, a graphics accelerator for a personal computer having only the Gouraud shading function and not having the Phong shading function is constructed.
Even the two-dimensional image generation unit 17 can display a three-dimensional image with a specular reflection effect. It should be noted that the present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the gist thereof.

[0047]

According to the first aspect of the present invention, even a computer system having only the function of Gouraud shading and having a relatively inexpensive configuration with a limited operation speed is provided with a mirror reflection effect. Natural images can be obtained.

According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the image for the specular reflection effect and the image of the texture pattern are superimposed and pasted, thereby realizing a more natural picture. Image can be obtained.

According to the third and fourth aspects of the present invention, even a computer system having only the function of Gouraud shading and having a relatively inexpensive configuration with a limited operation speed is provided with a mirror reflection effect. It is possible to draw a natural image.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration according to an embodiment of the present invention.

FIG. 2 is an exemplary flowchart showing an operation processing procedure according to the embodiment;

FIG. 3 is a view exemplifying an image for a specular reflection effect by the point light source according to the embodiment;

FIG. 4 is a view showing various vectors for a surface polygon according to the embodiment;

FIG. 5 is a view showing a light source direction coordinate system according to the embodiment;

FIG. 6 is a diagram showing a function of a polar coordinate value and a specular reflection coefficient according to the embodiment;

[Explanation of symbols]

 Reference Signs List 11 arithmetic processing unit 12 storage unit 12a storage medium 13 main memory 14 input unit 15 three-dimensional shape storage unit 16 mirror reflection effect image storage unit 17 three-dimensional image generation unit 18 texture image storage unit 19: Display B: Bus

Claims (4)

[Claims] A first storage unit for storing three-dimensional shape information having normal information of all vertices; a second storage unit for storing an image for a mirror reflection effect corresponding to a shape of a light source; First designating means for designating the position of the three-dimensional shape in the whole space; second designating means for designating the viewpoint position and light source position in the whole space; and second designating means for designating the specular reflection coefficient of the three-dimensional shape. 3 and the normal position information of the vertices of the three-dimensional shape, the position in the whole space, the viewpoint position, the light source position, and the specular reflection coefficient to determine the paste position of the image for the specular reflection effect corresponding to the vertex. An attaching position calculating means for calculating, and a three-dimensional shape obtained by attaching an image for specular reflection effect according to an attaching position of the image for specular reflection effect calculated for each vertex constituting the three-dimensional shape, to the viewpoint position. Accordingly, an image processing apparatus comprising: an image generating unit that generates the three-dimensional display image by performing perspective projection on a projection plane. 2. The image generating means according to claim 1, wherein the image for specular reflection effect and the image pattern stored in advance are stored in accordance with the position of the image for specular reflection effect calculated for each vertex of the three-dimensional shape. The image processing apparatus according to claim 1, wherein the image processing apparatus is superimposed and attached. 3. A first storage process for storing three-dimensional shape information having normal information of all vertices, a second storage process for storing an image for a mirror reflection effect corresponding to a shape of a light source, A first designation process of designating a position of the three-dimensional shape in the whole space; a second designation process of designating a viewpoint position and a light source position in the whole space; and a second designation process of designating a specular reflection coefficient of the three-dimensional shape. 3 and, based on the normal information of the vertices of the three-dimensional shape, the position in the whole space, the viewpoint position and the light source position, and the specular reflection coefficient, determine the paste position of the image for the specular reflection effect corresponding to the vertex. Calculating a pasting position calculation process, and setting the three-dimensional shape obtained by pasting the specular reflection effect image according to the pasting position of the specular reflection effect image calculated for each vertex constituting the three-dimensional shape to the viewpoint position. Accordingly, there is provided an image processing method for generating a three-dimensional display image by performing perspective projection on a projection plane. 4. A first storage step of storing three-dimensional shape information having normal information of all vertices, a second storage step of storing an image for a mirror reflection effect corresponding to a shape of a light source, A first designation step of designating a position of the three-dimensional shape in the whole space, a second designation step of designating a viewpoint position and a light source position in the whole space, and a second designation step of designating a specular reflection coefficient of the three-dimensional shape. 3 specifying the normal position information of the vertices of the three-dimensional shape, the position in the whole space, the viewpoint position and the light source position, and the specular reflection effect image corresponding to the vertex, based on the specular reflection coefficient. Calculating a pasting position calculating step, and setting the three-dimensional shape obtained by pasting the specular reflection effect image according to the pasting position of the specular reflection effect image calculated for each vertex of the three-dimensional shape to the viewpoint position. Therefore, a storage medium storing a computer program for executing the image generating step of generating the three-dimensional display image by performing perspective projection on a projection plane.