JP2004102900A - Image generating method and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a high quality image with partially different quality with less number of processing steps. <P>SOLUTION: The lengths of normal vectors on a normal map are differentiated according to the difference of the quality of a corresponding texture image. A write vector is multiplied by the texture image to generate a rendering image by diffuse light, the inner product of a half angle vector by the normal vector on the normal map corresponding to the texture image is calculated, and the inner product value is multiplied by a specified specular color to generate the rendering image by specular light. Then, the rendering image by the diffuse light and the rendering image by the specular light are added to each other to generate an output image. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image generation method and an apparatus for generating an image when a three-dimensional model is viewed from a viewpoint by setting a three-dimensional model, a light source, and a viewpoint in a three-dimensional space, and in particular, a bump mapping technique using a normal map. The present invention relates to a method and an apparatus for generating images having partially different textures by applying the method.
[0002]
[Prior art]
For example, a virtual reality (VR) system includes various three-dimensional models in a three-dimensional coordinate system three-dimensional space virtually represented by three coordinate axes (X, Y, and Z axes) orthogonal to each other in a computer. Setting a light source, setting a viewpoint that can freely move in the three-dimensional space by an input signal from an input device, generating an image of the three-dimensional space viewed from this viewpoint, and displaying the image on a screen such as a screen or a display. Thus, the viewer can get into the virtual space and feel as if he / she is looking at the three-dimensional model.
[0003]
By the way, the surface of the three-dimensional model has various patterns. These patterns are stored in advance in a storage device in a computer as image data called a texture. Then, at the time of image generation, the texture image is pasted on the surface of the corresponding three-dimensional model, shaded (shaded) depending on the viewpoint and the position of the light source, and displayed on the screen.
[0004]
In addition, a more realistic image may be obtained by giving a sense of unevenness to the pattern. It is also possible by shading to make a texture image having no unevenness look as if it has unevenness. Such shading is called bump mapping. As the bump mapping, a technique using a normal map is generally used.
[0005]
FIG. 13 shows an example of the normal map 1. This normal map 1 is created corresponding to the image of the texture 2 shown in FIG. As shown in FIG. 15, the normal map 1 indicates the direction of a pixel p with respect to a three-dimensional coordinate system including the X axis, the Y axis, and the Z axis by using a normal vector S (X, Y, Z (Consisting of vector values), and the vector values of X, Y, and Z are converted into R (Red), G (Green), and B (Blue) values, respectively, and set for each pixel p. ing. Here, the lengths of the normal vectors S are all normalized to “1”. Therefore, the magnitude of the gradient of the normal vector S is in the range of −1.0 to 1.0, but since the color intensity is 0 to 255, for example, the normal vector S (X, Y, Z) becomes ( A flat portion of (0.0, 0.0, 1.0) becomes (R, G, B) = (127, 127, 255) and is expressed in blue.
[0006]
FIG. 16 is a flowchart showing a procedure of a conventional bump map process executed by an image generating apparatus that generates this type of image. That is, the image generation device acquires from the storage unit the texture 2 of the image to be pasted on the surface of the three-dimensional model and the normal map 1 created corresponding to the image of the texture 2 (ST1, ST2).
[0007]
Next, the image generation device calculates, for each pixel p, a light vector indicating the direction of the surface in the light source direction from the direction of the surface of the three-dimensional model to which the image of the texture 2 is pasted and the position of the light source ( ST3). Next, the image generation device calculates, for each pixel p, an inner product of the light vector and the normal vector S of the normal map 1 corresponding to the image of the texture 2 to obtain a diffuse (diffuse). A luminance value of each pixel p with respect to light is obtained (ST4). Thereafter, the image of the texture 2 is multiplied by the luminance value of each pixel p, which is the inner product operation result (inner product value), to generate a rendered image by diffuse light (ST5).
[0008]
Further, the image generation device calculates, based on the orientation of the surface of the three-dimensional model to which the image of the texture 2 is pasted and the positions of the light source and the viewpoint, the sum of the light direction from the light source on the surface and the line-of-sight direction from the viewpoint. A half-angle vector indicating the direction is calculated for each pixel p (ST6). Next, the image generation device calculates an inner product of the half-angle vector and the normal vector S of the normal map 1 for each pixel p, and calculates a luminance value of each pixel p with respect to specular (specular) light. (ST7). Thereafter, a predetermined specular color is multiplied by the luminance value of each pixel p, which is the result of the inner product operation, to generate a rendered image using specular light (ST8). Note that the specular color is determined by the type of light source that illuminates the surface on which the image of the texture 2 is to be pasted.
[0009]
When the rendering image by the diffuse light and the rendering image by the specular light are generated in this way, the image generating apparatus adds both rendering images to obtain a final output image (ST9). Then, the image generating apparatus outputs the final output image to the display device (ST10), and displays the final output image on a screen or a display screen.
[0010]
Either the rendering image generation process using the diffuse light in ST3 to ST5 or the rendering image generation process using the specular light in ST6 to ST8 may be performed first, or may be performed in parallel. Things.
[0011]
FIG. 17 shows an example of an image which has been subjected to shading by the conventional bump map processing. This image is obtained by pasting the image of texture 2 shown in FIG. 14 on the surface of a three-dimensional model showing a sliding door at the center of the screen. The image of texture 2 has gold foil pasted on parts other than pine. The bump map processing is applied to enhance the glossiness of the gold leaf. However, in the conventional bump map processing, the glossiness of the entire sliding picture is uniform, so that the entire sliding picture is expressed as glossy, and the gold foil portion is not noticeable.
[0012]
Therefore, as shown in FIG. 18, a texture 3 of a mask image in which a pine portion having no glossiness of a sliding door picture is blackened is prepared. Then, as shown by the broken line in FIG. 16, the image generation device multiplies the rendering image by the specular light by the image for mask to lower the luminance value of the mask portion (ST11), and then renders the rendering image by the diffuse light. The addition is performed (ST9) to obtain a final output image (ST10). By doing so, the luster of the pine portion where no gold leaf is stuck is suppressed, and the glossiness of the gold leaf is enhanced.
[0013]
Incidentally, in the case where the image shown in FIG. 17 is generated, FIG. 19 shows a rendering image of the specular light before applying the texture 3 of the mask image, and FIG. 19 shows a rendering image of the specular light after applying the texture 3 of the mask image. FIG. 20 shows the rendered image.
[0014]
[Problems to be solved by the invention]
However, when the texture 3 of the mask image is applied because the glossiness of the texture image is partially different, the complexity of creating the texture 3 of the mask image from the texture 2 image in advance is reduced. In addition, in addition to the texture 2 and the normal map 1, a storage area for storing and holding the texture 3 of the mask image is also required, and there is a problem that the storage capacity becomes large. In addition, since a processing step of multiplying the masked image by the rendered image by specular light is added, the processing is time-consuming, and it is necessary to generate images one after another in a very short time like a virtual reality system. Was unsuitable.
[0015]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an image generation method and an image generation method that can generate an image having a partially different texture with high quality in a small number of processing steps and can also save storage capacity. It is intended to provide such a device.
[0016]
[Means for Solving the Problems]
The present invention solves such a problem, and the invention corresponding to claim 1 sets a light source and a viewpoint, respectively, in a three-dimensional space, a three-dimensional model in which the texture of an image having a partially different texture is pasted, An image generation method for generating an image when a three-dimensional model is viewed from a viewpoint, wherein the texture image is multiplied by a light vector indicating a direction of a surface to which a texture image of the three-dimensional model is attached in a light source direction, and diffuse light is obtained. Generating a rendered image by using a half-angle vector indicating the sum of the light direction from the light source on the surface to which the texture image of the three-dimensional model is to be pasted and the line of sight from the viewpoint, and a normal map corresponding to the texture image Calculates the inner product with the normal vector of this, multiplies this inner product value by the specified specular color, and renders the image with specular light. Generating the output image by adding the rendered image by the diffuse light and the rendered image by the specular light, and calculates the length of the normal vector of the normal map by It is made different depending on the difference in texture.
[0017]
In the image generation method according to the first aspect of the present invention, the length of each normal vector set for each pixel of the normal map differs depending on the texture of the corresponding texture image. Therefore, the rendered image by the specular light is generated by calculating the inner product of the half-angle vector and the normal vector of the normal map and multiplying the inner product value by a predetermined specular color. , The brightness value of the specular light varies, and the difference in texture is expressed with high quality. If the lengths of the normal vectors are not uniform, the image information of the texture is lost at the time of calculating the diffuse light, resulting in darkening. Therefore, in the present invention, a rendering image by diffuse light is generated by simply multiplying the image data of the texture by the component in the height direction of the light vector so that the normal vector is not considered in the calculation of diffuse light. .
[0018]
The invention corresponding to claim 2 of the present invention is the invention according to claim 1, wherein the normal map corresponding to the texture of the image having a partially different glossiness is each normal vector set for each pixel. Among them, the normal vector of the pixel corresponding to the image whose glossiness is suppressed in the corresponding texture image is shorter than the normal vectors of the other pixels.
[0019]
In the image generating method according to the second aspect of the present invention, the normal vector of the normal map is the normal vector of the pixel corresponding to the image whose glossiness is suppressed in the corresponding texture image. It is shorter than the line vector. Therefore, in the rendered image by the specular light, the luminance of the specular light is reduced correspondingly in the portion where the normal vector is short, so that the glossiness of the image corresponding to this portion is suppressed.
[0020]
According to a third aspect of the present invention, in an image generating apparatus that sets a stereo model, a light source, and a viewpoint in a stereo space and generates an image when the stereo model is viewed from the viewpoint, the image generation apparatus pastes the stereo model. A storage unit for storing a texture image and a normal map corresponding to the texture image; and, when the texture image is an image having uneven glossiness, the direction of the surface on which the texture image of the three-dimensional model is pasted in the light source direction is determined. Diffuse light rendering means for multiplying the texture image by the indicated light vector to generate a rendered image by diffuse light; and when the texture image is an image with uneven glossiness, a texture image of a three-dimensional model is pasted. A half-angle vector indicating the direction of the sum of the light direction from the light source on the surface to be viewed and the viewing direction from the viewpoint A specular light rendering means for calculating an inner product of the normal map corresponding to the texture image and a normal vector, multiplying the inner product value by a predetermined specular color to generate a rendered image by specular light, and a diffuse light rendering means Output image generating means for generating an output image by adding the rendered image by the diffuse light generated by the method and the rendered image by the specular light generated by the specular light rendering means, wherein the normal map is a normal vector Are different depending on the difference in texture of the corresponding texture images.
[0021]
In the image generating apparatus according to the third aspect of the present invention, the storage means stores the texture image to be pasted on the three-dimensional model and the normal map corresponding to the texture image by the storage means. Here, in the normal map, the length of the normal vector differs depending on the difference in the texture of the corresponding texture image.
[0022]
The rendered image by the diffuse light is generated by multiplying the component of the light vector in the height direction by the texture image. On the other hand, a rendered image by specular light is generated by calculating an inner product of a half-angle vector and a normal vector of a normal map corresponding to the texture image, and multiplying the inner product value by a specular color. Thus, the rendered image by the diffuse light and the rendered image by the specular light are added to generate an output image having a partially different texture depending on the length of the normal vector.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In this embodiment, a case will be described in which a stereoscopic space image displayed by a virtual reality system is generated.
[0024]
FIG. 1 is a block diagram illustrating a main configuration of an image generation device 10 according to the present embodiment. The image generation device 10 is configured by a computer such as a personal computer or a workstation.
[0025]
The image generation device 10 converts various signals input from the input device 20 into input commands having the corresponding contents, an input signal conversion unit 11 that supplies the input commands to the image generation calculation unit 13, and a model file 121. , A light source file 122, a texture file 123, a normal map file 124, etc., a data storage unit 12 as storage means for storing and storing various data files, and the data storage according to an input command given from the input signal conversion unit 11. An image generation operation unit 13 that generates a stereoscopic space image using the data of the unit 12, a frame memory 14 that stores data of the stereoscopic image generated by the image generation operation unit 13, and a storage in the frame memory 14. D / A (D / A) that reads out the converted image data, converts it into an analog video signal, and outputs it to the display device 30. And a digital / analog) converter unit 15.
[0026]
The input device 20 is for moving the position of the viewpoint and the direction of the line of sight set in the three-dimensional space. The display device 30 projects and displays a stereoscopic space image on a screen such as a screen or a display.
[0027]
The model file 121 stores data relating to the shape, position, and the like of various three-dimensional models set in the three-dimensional space. FIG. 2 shows an example of the data record 41 stored and saved in the model file 121. In FIG. 2, the item “model ID” is a unique code set for each model in order to uniquely identify various three-dimensional models. For example, the file name may be a uniquely determined file name for each model. The item “shape data” is data indicating the coordinates of each vertex of the three-dimensional shape of the three-dimensional model to which the corresponding model ID is set. In the item “position coordinates”, a three-dimensional model with a corresponding model ID is installed in a three-dimensional coordinate system three-dimensional space virtually represented by three coordinate axes (X axis, Y axis, and Z axis) orthogonal to each other. This is data indicating position coordinates. The item “texture No” is an identification symbol for specifying a texture image to be pasted on the surface of the three-dimensional model to which the corresponding model ID is set. This identification symbol may be, for example, the file name of the texture image.
[0028]
The light source file 122 stores data relating to various light sources set in the three-dimensional space. FIG. 3 shows an example of the data record 42 stored in the light source file 122. In FIG. 3, the item “light source ID” is a unique code uniquely set for each light source to identify various light sources. The item “type” is data indicating the type of light source (infinite light source, point light source, line light source, environmental light, etc.) for which the corresponding light source ID is set. The item “position coordinates” is data indicating the position coordinates where the light source of the corresponding light source ID is installed in the three-dimensional space of the three-dimensional coordinate system.
[0029]
The texture file 123 stores and stores texture data indicating a pattern, a material, and the like to be pasted on the surface of each of the three-dimensional models. FIG. 4 shows an example of a data record stored and saved in the texture file 123. In FIG. 4, the item “texture No.” is a unique identification symbol set for each texture to identify each texture data. For example, the texture No. may be a file name of the texture data. The item “image data” is image data of a texture in which a corresponding texture number is set. The item “normal map No.” is an identification symbol that specifies a normal map created from the texture image of the corresponding texture No. For example, the normal map number may be a file name of the normal map data. The item “gloss flag” is data for identifying whether or not the texture image of the corresponding texture No. is an image having uneven glossiness.
[0030]
Further, the texture file 123 may include an item called “rendering instruction”. The rendering instruction describes an instruction for rendering the surface of the model. For example, the rendering instruction is a normal bump mapping for the model A, a normal map A and a normal map B for the model B, a normal map B for the model C, and a normal map B for the model D. A three-dimensional model is associated with a method, such as a normal map E required for implementing the present invention. By describing such a rendering instruction in a file, it is possible to associate different solid models with the same technique such as a normal map. This eliminates the need to record duplicate normal maps.
[0031]
The normal map file 124 stores data relating to a normal map generated from various texture images. FIG. 5 shows an example of a data record stored in the normal map file 124. In FIG. 5, the item "normal map No." is a unique identification symbol set for each normal map to identify each normal map. Each "normal map data" is a normal vector of each pixel of the normal map to which the corresponding normal map No. is set.
[0032]
Further, the records of the various files in FIGS. 2 to 5 may be aggregated into one file and one record. In this case, duplicate items are omitted.
[0033]
Here, in the present embodiment, the constraint of normalizing the length of each normal vector performed by the conventional method to 1 is removed, and the normal vector of each normal vector set for each pixel of the normal map is removed. The size differs depending on the difference in the texture of the corresponding texture image. Such a normal vector is calculated by, for example, the following equation (1).
[0034]
(R, G, B) = [(r, g, b) − (127, 127, 127)] × α + (127, 127, 127) (1)
Here, r, g, and b are RGB values respectively corresponding to the X, Y, and Z vectors when the normal vector is normalized to 1. α is optional within the range of 0 ≦ α ≦ 1.
[0035]
Now, in the image generation device having such a configuration, the image generation calculation unit 13 sets various solid models set in the model file 121 and various light sources set in the light source file 122 in the three-dimensional space of the three-dimensional coordinate system. When the position of the viewpoint and the direction of the line of sight are determined by an input signal from the input device 20, an image of a three-dimensional space viewed from the viewpoint is generated. At this time, the image generation calculation unit 13 performs a bump map process on a predetermined three-dimensional model, and pastes a texture image having a sense of unevenness on the surface of the three-dimensional model.
[0036]
FIG. 6 is a flowchart illustrating a procedure of the bump map process executed by the image generation calculation unit 13. First, when acquiring the texture number of the image data of the texture to be attached to the model from the data record 41 relating to the three-dimensional model acquired from the model file 21, the image generation calculation unit 13 reads the data record of the texture number from the texture file 123 as ST 21. Read 43.
[0037]
Next, the image generation calculation unit 13 detects the normal map number from the texture data record 43 in ST22, and reads the data record 44 of the normal map number from the normal map file 124.
[0038]
Next, the image generation calculation unit 13 checks the gloss flag of the texture data record. When the gloss flag indicates that the image has an uneven glossiness, a rendering image generation process using diffuse light shown in ST24 and ST25 and a rendering image generation process using specular light shown in ST26 to ST28 are executed. This processing may be performed first, or both may be processed in parallel.
[0039]
That is, the image generation calculation unit 13 calculates, for each pixel p, a light vector indicating the direction of the surface in the light source direction from the orientation of the surface of the three-dimensional model to which the texture image is pasted and the position of the light source in ST24. . In step ST25, the image generation calculation unit 13 converts the height component of the light vector (normally, the Z-axis component of the light vector) into the image data (texture image data) of the texture data record 43 read from the texture file 123. ) To generate a rendered image by diffuse light (diffuse light rendering means).
[0040]
Further, the image generation calculation unit 13 determines the light direction from the light source on the surface and the line-of-sight direction from the viewpoint from the orientation of the surface of the three-dimensional model to which the texture image data is pasted and the positions of the light source and the viewpoint in ST26. Is calculated for each pixel. Next, the image generation operation unit 13 calculates an inner product of the half-angle vector and the normal map data (normal vector S) of the normal map data record 44 read from the normal map file 124 for each pixel. Then, an inner product value of each pixel with respect to the specular light, that is, a luminance value is obtained. Then, a predetermined specular color is multiplied by a luminance value of each pixel, which is a result of the inner product operation, to generate a rendering image by specular light. The specular color is determined by the type of light source that illuminates the surface on which the texture image is to be pasted.
[0041]
After the rendering image by the diffuse light and the rendering image by the specular light are generated in this way, the image generation calculation unit 13 adds both rendering images to obtain a final output image in ST29. Then, the image generation calculation unit 13 draws and outputs this final output image to the frame memory 14 in ST30.
[0042]
The image data of the final output image drawn in the frame memory 14 is converted into an analog video signal by the D / A converter 15 and displayed on the screen such as a screen or a display by the display device 32. .
[0043]
In the present embodiment configured as described above, for example, when the three-dimensional space image shown in FIG. 12 is generated, the texture of the fusuma picture to be pasted on the surface of the three-dimensional model forming the fusuma at the center of the screen is used in advance. 7 is stored in the texture file 123, and as a normal map corresponding to the texture 2 image, as shown in FIG. The normal map 1 ′ in which the normal vector is shorter than the normal vector of the pixel corresponding to the glossy gold foil portion is stored in the normal map file 124.
[0044]
Then, when the image generation operation unit 13 executes the bump map process on the three-dimensional model, a light vector as shown in FIG. 8 is calculated, and the height component of the light vector is added to the image data of the texture 2. The multiplication is performed to generate a rendering image by the diffuse light as shown in FIG. Also, a half angle vector as shown in FIG. 9 is calculated, and an inner product of the half angle vector and the normal vector of the normal map 1 'is calculated. Is multiplied to generate a rendering image by specular light as shown in FIG. Then, the rendering image by the diffuse light and the rendering image by the specular light are added to obtain a final output image as shown in FIG. In this final output image, the glossiness of the portion where the normal vector of the normal map 1 'is short, that is, the pine portion having no glossiness is suppressed, and conversely, the portion where the normal vector is long, that is, the gold foil is attached. The glossiness of the part where it is located is enhanced, and an image with a quality equal to or close to that obtained when texture 3 of the conventional mask image is used is obtained.
[0045]
Therefore, according to the present embodiment, since the texture 3 of the mask image can be made unnecessary, it is possible to eliminate the trouble of creating the texture 3 of the mask image and to store the texture of the mask image. The storage capacity of the unit can also be saved. Further, the processing step of multiplying the rendering image by the specular light by the texture 3 of the mask image becomes unnecessary, and the number of processing steps is reduced, so that the processing time can be reduced.
[0046]
In addition, if the lengths of the normal vectors are not uniform, there is a possibility that the image information of the texture may be damaged and darkened during the calculation of the diffuse light. Since the rendering image by the diffuse light is generated only by multiplying the image component of the texture by the component in the height direction of the light vector so as not to consider the above, such a problem cannot occur.
[0047]
The present invention is not limited to the image generation technology in the virtual reality system, and can be applied to, for example, generating a three-dimensional space image in a CG animation or a TV game.
[0048]
The present invention is also effectively applied to generation of an image having a different texture other than the gold foil portion.
[0049]
Further, in the prior art, the luminance value of the diffuse light is obtained by calculating the inner product of the light vector and the normal vector, but in the present invention, the normal vector is vertically upward (0, 0) in all pixels. , 1), the luminance value is obtained only from the height component of the light vector. Therefore, according to the present invention, if the three-dimensional space image is a flat surface that receives light uniformly, it is possible to produce even more texture and glossiness.
[0050]
【The invention's effect】
As described in detail above, according to the invention corresponding to the first aspect, it is possible to provide an image generation method that can generate an image having a partially different texture with high quality in a small number of processing steps and can also save storage capacity.
[0051]
According to the second aspect of the present invention, it is possible to provide an image generating method capable of generating an image having a partially different glossiness with high quality in a small number of processing steps and saving storage capacity.
[0052]
According to the third aspect of the present invention, it is possible to provide an image generating apparatus that can generate an image having a partially different texture with high quality in a small number of processing steps and can save storage capacity.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of an image generating apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing an example of a data record stored in a model file of the image generation device according to the embodiment.
FIG. 3 is a schematic diagram showing an example of a data record stored in a light source file of the image generation device according to the embodiment.
FIG. 4 is a schematic diagram showing an example of a data record stored in a texture file of the image generation device according to the embodiment.
FIG. 5 is a schematic diagram showing an example of a data record stored in a normal map file of the image generating apparatus according to the embodiment.
FIG. 6 is a flowchart showing a main procedure of a bump map process executed by an image generation calculation unit of the image generation device according to the embodiment.
FIG. 7 is an image showing a normal map used in the embodiment.
FIG. 8 is a conceptual diagram of a light vector calculated in the embodiment.
FIG. 9 is a conceptual diagram of a half-angle vector calculated in the embodiment.
FIG. 10 is a rendering image using diffuse light generated in the embodiment.
FIG. 11 is a rendering image by specular light generated in the embodiment.
FIG. 12 is a final output image generated in the embodiment.
FIG. 13 is an image showing a normal map used in the conventional description.
FIG. 14 is an image showing a texture used in the embodiment and the conventional description.
FIG. 15 is a conceptual diagram used for describing a normal map.
FIG. 16 is a flowchart showing main steps of a conventional bump map process performed at the time of image generation.
FIG. 17 is an output image generated by a conventional bump map process.
FIG. 18 is an image for mask used conventionally.
FIG. 19 is a rendering image by specular light generated by a conventional bump map process.
FIG. 20 is a rendering image using specular light generated by a bump map process using a conventional mask image.
[Explanation of symbols]
1, 1 '... normal map
2. Texture
10 ... Image generation device
11 Input signal conversion unit
12 Data storage unit
13 ... Image generation operation unit
14. Frame memory
15 D / A converter
20 input device
30 Display device
121 ... Model file
122: Light source file
123 ... texture file
124 ... Normal map file

Claims (3)

An image generation method for setting a three-dimensional model in which texture of an image having a partially different texture is pasted in a three-dimensional space, a light source, and a viewpoint, and generating an image when the three-dimensional model is viewed from the viewpoint. ,
Generating a rendering image by diffuse light by multiplying the texture image by a light vector indicating the direction of the light source direction of the surface on which the texture image of the three-dimensional model is pasted;
A half-angle vector indicating the direction of the sum of the light direction from the light source and the line-of-sight direction from the viewpoint on the surface of the three-dimensional model to which the texture image is pasted, and a normal vector of a normal map corresponding to the texture image Calculating a dot product of the specular color and multiplying the dot product value by a predetermined specular color to generate a rendered image by specular light;
Generating an output image by adding the rendered image by the diffuse light and the rendered image by the specular light,
An image generation method, wherein the length of a normal vector of the normal map is varied depending on a difference in texture of a corresponding texture image. The image generation method according to claim 1,
The normal map corresponding to the texture of an image having a partially different glossiness is a normal vector of a pixel corresponding to an image in which the glossiness is suppressed in the corresponding texture image among the normal vectors set for each pixel. An image generation method, wherein a vector is shorter than a normal vector of another pixel. In an image generating apparatus that sets a stereo model, a light source, and a viewpoint in a stereo space, and generates an image when the stereo model is viewed from the viewpoint,
Storage means for storing a texture image to be pasted on the three-dimensional model and a normal map corresponding to the texture image;
When the texture image is an image with uneven glossiness, the texture image is multiplied by a light vector indicating the direction of the surface of the three-dimensional model to which the texture image is pasted, in the direction of the light source, and diffuse light is used. Diffuse light rendering means for generating a rendered image;
When the texture image is an image having unevenness in glossiness, a half indicating the sum of the light direction from the light source and the line of sight from the viewpoint on the surface of the three-dimensional model to which the texture image is pasted Specular light rendering means for calculating an inner product of an angle vector and a normal vector of a normal map corresponding to the texture image, and multiplying the inner product value by a predetermined specular color to generate a rendered image by specular light,
Output image generating means for generating an output image by adding a rendered image by diffuse light generated by the diffuse light rendering means and a rendered image by specular light generated by the specular light rendering means,
The image generating apparatus according to claim 1, wherein the normal map is obtained by changing the length of a normal vector according to a difference in texture of a corresponding texture image.

Images