JP2000172873A - Method for displaying picture of object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for displaying picture of object by which the color of an object can be expressed faithfully. SOLUTION: The spectral solid-angle reflectance of an object is inputted or measured (100) and the spectral distribution of a main light source is found by using the solid-angle reflectance (102). Then the main light source is found (104) and the spectral distributions of the other light sources are found by using the solid-angle reflectance (106). In addition, the other light is found (108) and the complex index of refraction of the object is found by using an ellipsometer (110). Thereafter, the Fresnel coefficients rs and rp of the object are found by using the complex index of refraction (112) and, after finding the regular reflectance (f) of the object (114), the regular reflected light from the object is found (116). Then, the color of the object is computed by using the main light source, the other light, and regular reflected light (118).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object image display method and, more particularly, to an object image display method for faithfully reproducing the surface color when displaying the surface color of an object on a display device.

[0002]

2. Description of the Related Art In the field of computer graphics (so-called CG), which is capable of presenting an image display or the like with color on a computer and printing the image, an image such as a pattern or figure with various colors is displayed on a screen. In some cases, the displayed image is printed or the displayed color image is printed. When an object is to be displayed as an image with color, the principle of light reflection is modeled and expressed by the luminance of light, but the expression of the object by luminance alone is not enough to express the color of the object. It was difficult to express a substantial color (color reproduction).

In recent years, it has become possible to output an image of a real object, for example, an image of an automobile, using computer graphics. By actually measuring both the reflectance of the light source and the material outdoors, the appearance of the object under arbitrary weather can be accurately expressed. This technology can be used effectively in the design field to evaluate shapes and colors.

[0004] The present applicant has proposed a color graphic apparatus as an apparatus that has attempted to reproduce the color of an object (see Japanese Patent No. 2806003). This color graphic apparatus attempts to reproduce colors, that is, faithfully reproduce the color of an object, in consideration of changes in the appearance of colors due to the environment such as weather and time, and differences in the spectral distribution of the light source.

[0005]

However, objects often have a large difference in transmittance and reflectance, which greatly affect the appearance depending on the composition, physical properties, and surface shape inherent to the object. For example, the surface of an object such as a vehicle body may have a gloss, and may be expressed as a color having a different appearance depending on the gloss. In some cases, such a glossy object surface cannot be expressed as a desired paint color (a color having a sense of reality) intended by a user, a designer, or the like.

An object of the present invention is to provide an object image display method capable of faithfully expressing the color of an object in consideration of the above fact.

[0007]

Means for solving the problem The appearance of an object is mainly
The colors can be classified into the ground color and the reflection color, and the ground color can be accurately represented by measuring the diffuse reflectance. On the other hand, the reflected color can be accurately represented by measuring the regular reflectance, but measuring the regular reflectance is more difficult than measuring the diffuse reflectance. The present inventor pays attention to this regular reflectance, and the regular reflectance of the glass or the painted surface of an automobile is substantially the same because it does not include internal absorption, that is, the refractive index is 1.5.
It has been found that the reflection coefficient coincides with the Fresnel reflection coefficient of about 3.

However, since metal platings and resins, which are common in automobile parts, have internal absorption, they are clearly different from the regular reflectance of glass and painted surfaces, and need to be determined accurately.

Therefore, the present inventor has extended the conventional expression of the refractive index to a complex number in order to take into account the absorption inside the material with respect to the regular reflectance related to the reflected color.
That is, the real part is represented by the refractive index and the imaginary part is represented by the absorption coefficient.

In the object image display method according to the first aspect of the present invention, a spectral solid angle reflectance of an object is input, and a spectral distribution of a main light source illuminating the object is determined based on the spectral solid angle reflectance. In addition, the spectral distribution of the light source other than the main light source was determined, refractive index information including internal absorption of the surface material of the object was input, and the spectral distribution of specularly reflected light was determined and determined using the refractive index information. The display data of the object is created based on the spectral distribution of the main light source, the spectral distribution of another light source, and the spectral distribution of specular reflection light, and an image of the object is displayed based on the display data.

According to a second aspect of the present invention, there is provided the object image display method according to the first aspect, wherein the refractive index information includes a real part indicating a refractive index of a surface material of the object and an internal absorption of the surface material. A complex refractive index composed of an imaginary part representing is input.

According to a third aspect of the present invention, there is provided the object image displaying method according to the second aspect, wherein the complex index of refraction is a difference between an incident angle of light and a phase difference between s-wave and p-wave of polarized light. It is characterized in that a relationship is determined in advance and is determined based on the relationship.

In the present invention, the spectral solid angle reflectance of an object is input. The spectral solid angle reflectance can be measured by a spectral solid angle reflectance measuring device. Based on the spectral solid angle reflectance, a spectral distribution of a main light source (for example, sunlight) illuminating the object is obtained. At the same time, the spectral distribution of the light source other than the main light source is obtained. Next, in order to obtain the spectral distribution of light when the object is actually visually observed, it is necessary to obtain regular reflection light.
Conventionally, the regular reflectance of glass was used as the regular reflectance required to determine the regular reflection light, but in the present invention, the internal absorption of the surface material of the object is included to take into account the internal absorption. Enter the refractive index information. Next, the spectral distribution of the specularly reflected light is determined using the refractive index information. Then, display data of the object is created based on the obtained spectral distribution of the main light source, the spectral distribution of the other light source, and the spectral distribution of the specularly reflected light, and an image of the object is displayed based on the created display data. By doing so, an object having a regular reflectance different from that of glass, such as a metal or a resin having gloss, can be faithfully represented.

The refractive index information may employ a complex refractive index composed of a real part representing the refractive index of the surface material of the object and an imaginary part representing the internal absorption of the surface material. The regular reflectance can be expressed by elliptically polarized light, and the calculation is facilitated by the complex number expression based on the description of s-wave and p-wave of elliptically polarized light.

Further, the complex refractive index is defined by an incident angle of light,
The relationship between the polarization s-wave and the phase difference between the p-waves can be determined in advance, and the relationship can be determined based on the relationship. That is, the elliptically polarized light is the amplitude reflectance of s-wave and p-wave according to Fresnel's law,
And the phase difference of each component of the s-wave and the p-wave, and the complex refractive index can be easily obtained from these relationships.

The complex refractive index can also be obtained by using a polarization analyzer (so-called ellipsometer).
That is, the complex refractive index in such a representation can be obtained by a polarization analysis method from reflected light measured by a polarization analyzer such as a spectroscopic ellipsometer, and an accurate Fresnel reflection coefficient of an object can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the present embodiment, the present invention is applied to an expression when designing an object having a color such as a paint color (outer plate color) of an exterior of an automobile as an image output of the automobile.

That is, in the present embodiment, in order to improve the sense of reality of a car image output with a sense of reality using computer graphics (CG), parts of the car are accurately represented. In the present embodiment, accurate reflection is calculated by measuring the complex refractive index of the component using a spectral ellipsometer and calculating the reflection coefficient of Fresnel based on the measured complex refractive index.

The color of the outer panel of an automobile is roughly classified into a solid paint containing a color pigment as a main component, a color pigment, and a metallic paint containing a glitter material as a main component. The solid paint exhibits a substantially constant color irrespective of the direction in which light is irradiated or viewed. On the other hand, metallic paints are characterized by the fact that the color (especially the brightness) changes depending on the direction of light irradiation and the direction of viewing, and the behavior of the color change due to this direction is important for the paint (on design). Characteristics. In recent years, with the development of a new glittering material, the variation in the behavior of color change depending on the direction is increasing, and the ratio of metallic paints is also increasing in the automobile market. The computer graphics device of the present embodiment provides a method of accurately reproducing (displaying) a painted object (metallic paint) on a CRT, and can support the design of paint and the development of paint materials.

Considering the coating texture of the coating object from the optical characteristics, the appearance of the coating object is determined by the light reflection characteristic (spectral reflectance) of the coating film, which is a specular reflection component (specular reflection component) and an intra-layer diffuse reflection component. (Diffuse reflection component).

In the embodiment of the present invention, in order to reproduce an object color, the spectral reflectance of the object surface is used as a physical quantity for handling the object color. Note that this spectral reflectance is
In the case of a sample having a complicated shape, for example, in the case of a surface such as a fiber or a metallic coating, measurement may be performed at different values depending on the light receiving direction of the measuring instrument. The spectral solid angle reflectance, which is a three-dimensional spectral reflectance obtained by changing a light receiving angle or the like to a light receiving element that receives light, is used.

As shown in FIG. 2, the computer graphics device for expressing the object color includes a personal computer 16. This personal computer 1
Reference numeral 6 denotes a keyboard 10 for inputting color data and the like, and a computer main body 1 for calculating related data for expressing a desired object color in accordance with a program stored in advance.
2 and a CRT 14 for displaying an object color or the like, which is a calculation result of the computer main body 12. The computer main body 12 includes a CPU, a ROM, and a RAM, and further has a memory for storing data such as a spectral solid angle reflectance described later.

First, the outline of the present invention will be described. The color of the object can be obtained from the spectral distribution (spectral radiance) of the light incident on the eyeball when the object is visually observed. The spectral radiance I (λ) can be determined from three lights, for example, a main light source such as the sun (hereinafter, referred to as a main light source), specularly reflected light, and other light (details will be described later). Actual measured values can be used for the spectral solid angle reflectance required for obtaining the main light source and other light.

On the other hand, in order to obtain the specular reflection light, the regular reflectance is necessary. However, it is difficult to measure the regular reflection light, and conventionally, the specular reflectance of glass which can be calculated theoretically is used instead. I was However, since a metal, a glossy resin, or the like has a regular reflectance different from that of glass, it is difficult to reproduce the expression by using the regular reflectance of the glass instead. That is,
Specular reflection is also reflection that determines the degree of reflection of a glossy object, and also greatly contributes to the realism when the object is displayed as an image.

Therefore, the present inventor introduces the concept of a complex refractive index in order to accurately determine the regular reflectance, and can calculate an accurate reflection by determining the Fresnel reflection coefficient.

That is, in order to output a realistic image of a car by computer graphics (CG), the present inventor measured both the light source and the reflectance of a material outdoors to obtain an image of a car under arbitrary weather conditions. We have confirmed that we can accurately represent the appearance of things on the screen. This can be used effectively for evaluation of shapes and colors in the field of design. When such a CG image is presented and used as a substitute for an advertising catalog or the like, it is necessary to express small parts such as automobile parts in the same way as an actual vehicle to enhance the overall sense of reality.

The appearance of objects can be mainly classified into the ground color and the reflected color, and the ground color can be accurately represented by measuring the diffuse reflectance. On the other hand, the reflected color can be accurately represented by measuring the regular reflectance, but measuring the regular reflectance is generally more difficult than measuring the diffuse reflectance. Paying attention to the regular reflectance, the regular reflectance of the glass or painted surface of an automobile is almost the same because it does not include internal absorption.
That is, the refractive index coincides with the reflection coefficient of Fresnel around 1.53. However, since metal platings and resins, which are often present in automotive parts, have internal absorption, they are clearly different from the regular reflectance of glass and painted surfaces, and it is important to accurately determine this.

In order to consider the regular reflectance related to the color of reflection including the absorption inside the material, the expression of the refractive index is represented by introducing the concept of a complex number. That is, the real part was represented by the same refractive index as the conventional one, and the imaginary part was represented by the absorption coefficient.
The complex refractive index was determined from the reflected light measured by a spectroscopic ellipsometer by ellipsometry. As a result, it has been found that an accurate Fresnel reflection coefficient of an automobile part can be obtained.

Here, in the present embodiment, a reflection equation is used for the appearance of an object. This reflection equation will be described. Here, a reflection equation using the previously measured spectral solid angle reflectance R (λ) and the regular reflectance f will be described. Further, as shown in FIG. 7, the spectral solid angle reflectance R (λ) refers to the reflectance measured while changing the angle φ with respect to the regular reflection direction.

As shown in FIG. 3A, the incident light L (λ) irradiated from the range of the solid angle Δωs is reflected on the object surface (Object).
When reflected at ct), the spectral radiance of the light incident on the line of sight is Ls (λ), that is, the line of sight light Ls (λ) with respect to the incident light at the solid angle Δωs can be expressed by the following equation (1).

[0031]

(Equation 1)

Where β (λ) is the spectral radiance factor

As shown in FIG. 3B, when the object surface is replaced with a perfect diffuse reflecting surface, the spectral radiance J _S (λ) of light reflected by the perfect reflecting diffuser is , Can be expressed by the following equation (2).

[0034]

(Equation 2)

Here, since the above-mentioned spectral radiance factor β (λ) is an ideal value, it cannot be actually measured. Therefore, a measurable spectral solid angle reflectance R (λ) is used instead of the spectral radiance factor β (λ). In equation (1), β (λ) is R
Substituting equation (2) for (λ), the following equation (3) is obtained.

[0036]

(Equation 3)

Where L (λ), Js (λ), Ls (λ)
The unit of (W · sr^-1・ M^-2・ Nm ^-1).

In the above equation (3), the solid angle Δω _S is defined as dω _S
Then, by integrating the right side, the spectral radiance I (λ) of the line-of-sight light with respect to the incident light at the solid angle Ω can be obtained, and this spectral radiance I (λ) (W · sr−1 · m−2 · nm)
-1) can be expressed by the following equation (4).

[0039]

(Equation 4)

Here, ε (λ) is a general necessary term as light emitted from the object itself, but ε (λ) = 0 can be set since the painted surface does not emit light by itself. Since the same applies to transmission, only reflection is considered for the sake of simplicity, and mathematical expressions and descriptions relating to transmission are omitted.

As shown in FIG. 4, the solid angle Ω is converted into three solid angles Ω _R in the regular reflection direction, solid angle Ω _S in the main light source (here, the sun) direction, and solid angles Ω _{G in} the other directions. If considered separately, it can be expressed by the following equation.

[0042]

(Equation 5)

Here, the suffixes R, S, and G mean the reflectance and the light source for the light sources in the regular reflection direction, the main light source direction, and other directions, respectively. As described above, three types of light, the main light source, the specular reflection light, and the other light can be considered.

Here, if f (λ) is the regular reflectance at the incident angle θ _R , the regular reflectance f (λ) is the spectral radiance L _R ^O
Since (λ) is divided by the spectral radiance L _R (λ) of the incident light, it can be formally transformed into the following equation (5).

[0045]

(Equation 6)

However, R _R (λ) shown in the following equation (6)
According to the definition, the regular reflectance f (λ) can be expressed by Expression (7).

[0047]

(Equation 7)

Therefore, the spectral radiance I (λ) of the line-of-sight light
Can be expressed by the following equation (8).

[0049]

(Equation 8)

Here, on the painted surface, the regular reflectance f (λ) does not depend on the wavelength, and can be determined by the following equation (9). On the other hand, for metal and colored glass, f (λ) depends on the wavelength.

F (λ) ≡f (9) As described above, the measured spectral solid angle reflectance and the light source can be accurately incorporated into the present reflection equation. Therefore, the color of the object can be accurately calculated.

Next, ray tracing, which is known as a geometrical technique for finding an intersection with the object plane by tracing in the direction of the line of sight from the viewpoint, will be described.

Here, the wavelength λ is omitted for the sake of simplicity. As shown in FIG.
3,. . . , I,. . . , And regular reflection, and
Assuming that the line-of-sight light is I ₁ , the following equation (10) holds for the surface 1.

[0054]

(Equation 9)

Similarly, the following equation (11) holds for the surface i.

[0056]

(Equation 10)

Therefore, the following equation (13) can be obtained by sequentially calculating the line-of-sight light I ₁ from the above equations (10) and (11).

[0058]

[Equation 11]

From the above, the spectral distribution I ₁ of the line of sight light is obtained.
(Λ) can be obtained. By the way, if attention is paid only to the color, the line-of-sight light does not need to be in the form of a spectral distribution. For example, when represented by tristimulus values XYZ, the data amount is only three from the number of wavelength divisions (usually around 30). Easy. Therefore, when the tristimulus value XYZ is calculated from the line-of-sight light I ₁ (λ) according to the defining equation, it can be expressed by the following equation (14).

[0060]

(Equation 12)

The following formulas (15) and (16) are used to define the main light source direction and the light source directions such as these, and if these are calculated in advance, the above formula (14) is calculated every time. ,
The calculation can be performed faster than performing the spectral calculation for each wavelength. If the line of sight does not move and only the object color is changed, for example, the color of the vehicle body (15)
Since it is only necessary to recalculate the expression (16), the efficiency of the calculation can be improved.

[0062]

(Equation 13)

As described above, while the conventional ray tracing calculates the light intensity on the object at each node, the above method calculates the tristimulus value, so that the calculation load increases. The color can be calculated accurately without having to do it.

Next, the regular reflectance will be described. The regular reflectance of the glossy object surface can be expressed by the following equation (17) which is an extension of the Fresnel equation.

[0065]

[Equation 14]

Here, s is the energy of the s-wave, and p means the energy of the p-wave (light vibrates perpendicularly to its traveling direction, but the p-wave vibrates horizontally on the incident surface. S-wave is a wave that oscillates perpendicular to the plane of incidence).

[0067] However, and the case of a glass of colorless and transparent, in the case of a painted surface (approximately painted surface), r _s, r _p is, the following (1
8) and (19).

[0068]

(Equation 15)

Here, it is assumed that light travels from the medium 1 to the medium 2, and n ₁ and n ₂ are the refractive indexes of the medium 1 and the medium 2, respectively. theta ₁ is at an angle of incidence to the surface of the object incident light, theta ₂ is a transmission angle of the object inside surface of the transmitted light. θ ₁ and θ ₂ are given by the following (20)
It follows Snell's law shown in the equation.

[0070]

(Equation 16)

[0071] With this (20), the following equation Fresnel reflectance r _s, the r _p, respectively (21), can be expressed by equation (22).

[0072]

[Equation 17]

FIG. 6 shows the relationship between the angle and the reflectance with respect to the Fresnel equation. The dashed-dotted line is the bisector of the Fresnel equation for the p-wave and the s-wave, which is the conventional regular reflectance. It can be understood that the regular reflectance for the polarized light is an internal dividing point of the Fresnel equation of the p-wave and the s-wave, and an error occurs in the conventional equation.

However, many objects such as metal and resin do not conform to the above. In response to this,
In the method according to representations of measurement and automotive parts of the complex refractive index by spectroscopic ellipsometer, r _s, determine the r _p, we obtain the regular reflectance f.

Next, the measurement of the complex refractive index by a spectroscopic ellipsometer and the expression of an automobile part will be described.

The ellipsometer is also called an ellipsometer, and measuring a sample using an ellipsometer and obtaining a film thickness or a refractive index by an ellipsometry is called ellipsometry. The principle will be briefly described below.

When light is incident on the material surface (boundary surface) of the medium 1 from the medium 1, the polarization state of the specularly reflected light changes. Here, when the light E is incident on the material surface at an incident angle θ ₁ , the regular reflection light f becomes elliptically polarized light represented by the following equation (23).

[0078]

(Equation 18)

[0079] Here, r _s, r _p is s-wave according to the laws of the Fresnel and p-wave amplitude reflectance of, tan is amplitude reflectance ratio, delta is the phase difference between the s-component and p-component. This incident angle θ
_The ellipsometer measures ₁ and the phase difference Δ with high accuracy. From the following equations (24) and (25) representing the relationship between this and the optical constants n and κ of the substance, the optical constants n ₂ ,
it is possible to obtain the κ _2.

[0080]

[Equation 19]

For a surface with a coating, the reflection coefficient ratio ρ is
It can be expressed by the following equation (26).

[0082]

(Equation 20)

However, the reflection coefficient ratio δ is a phase delay caused by one round trip of the film, and can be expressed by the following equation (27).

Δ = 4πdn ₂ cos θ ₂ (27) where d: thickness of the thin film θ ₂ : refraction angle of the medium 2 From these, the thickness and the refractive index of the film can be obtained.
The above is the principle of ellipsometry.

Next, a method for calculating the Fresnel reflection coefficient from the complex refractive index will be described. In the present embodiment, the complex refractive indexes of the medium 1 and the medium 2 are defined by the following equations (28) and (29), respectively.

M ₁ = n ₁ −iκ ₁ (28) m ₂ = n ₂ −iκ ₂ (29) where n ₁ and n ₂ are the complex refractive indexes of the medium 1 and the medium 2, respectively. The real part, κ ₁ and κ ₂ are the imaginary parts of the complex refractive index of the medium 1 and the medium 2, respectively, and are called extinction coefficients and the like. i is an imaginary number unit (i ² = −1). Further, θ ₁ is an incident angle of a light beam from the medium 1 to the medium 2, and θ ₂ is a refraction angle of the light beam in the medium 2.

At this time, Equation (31) can be derived by Snell's law expressed by the following Equation (30).

[0088]

(Equation 21)

When the real part and the imaginary part of the right side of the above equation (31) are defined as the following equations (32) and (33), (3)
Equation (1) can be expressed by equation (34).

[0090]

(Equation 22)

Therefore, it can be transformed into the following equation (35).

[0092]

(Equation 23)

Thus, from the above equation (35), (3
8) and (39).

[0094]

(Equation 24)

In the equation (39), the right-hand side term is expressed as (4
If defined as (0) and (41), equation (39) can be expressed by equation (42).

[0096]

(Equation 25)

At this time, by using the expressions (34) and (42), the expression (43) can be derived, and the following expression (44) can be derived.

[0098]

(Equation 26)

On the other hand, r _p can be expressed by the following equation (47).

[0100]

[Equation 27]

Here, if a part of the right-hand side term of the equation (47) is replaced by the equation (48) and the equations (34) and (42) are used, the equation (49) can be derived.

[0102]

[Equation 28]

Then, the right side term of the equation (49) is changed to the following (5)
0) is defined.

[0104]

(Equation 29)

As a result, r _p can be expressed by the following equation (53), and the following equation (54) can be derived.

[0106]

[Equation 30]

The operation of the present embodiment will be described according to the outline and theory described above. When the power of the computer graphics device is turned on and the personal computer 16 starts operating, the processing routine shown in FIG. In step 100, the spectral solid angle reflectance of the object is input. The spectral solid angle reflectance of this object may be measured by a spectral solid angle reflectometer,
Further, the data storing the measured values may be read, or may be input from a keyboard. Next step 102
Then, the spectral distribution of the main light source is determined using the spectral solid angle reflectance input in step 100, and the main light source is determined in the next step 104.

In the next step 106, step 100
The spectral distribution of the other light source is determined using the spectral solid angle reflectance input in step (1), and other light is determined in the next step. In the next step 110, the complex refractive index is measured using an ellipsometer, and the measured value is input. The value of the complex refractive index to be input may be obtained by reading data that stores measurement values measured by an ellipsometer in advance,
Alternatively, it may be input from a keyboard. Next Step 11
In 2, the Fresnel coefficients r _s using a complex refractive index input in step 110, determine the r _p. Next, after obtaining the regular reflectance f in step 114, step 11
In step 6, specular reflection light is obtained. In the next step 118, the color of the object is calculated using the main light source, the other light, and the specularly reflected light obtained as described above, and this routine ends.

In the above step 110, (2
8) and (29) the refractive index of the medium 1 shown formula and the refractive index of the medium 2, and inputs the incident angle theta ₁ of the light beam from the medium 1 to the medium 2. In step 112, the A value of equation (32),
B value in equation (33), γ value in equation (36), ψ in equation (37)
Value, C value of expression (40), D value of expression (41), E value of expression (45), F value of expression (46), G value of expression (51), (5
2) Find the H value in the equation. Then, equation (44) s-wave energy reflectance of the (r _s), and determines and outputs the energy reflectance r _p of p wave (54) below.

As described above, in the present embodiment, since accurate reflection can be calculated by calculating the reflection coefficient of Fresnel using the complex refractive index of the automobile component, the glossy automobile component can be calculated. However, the parts can be accurately represented, and a computer image (CG) can be used to output a realistic image of an automobile.

Next, the result of comparison between the color of the object obtained by the computer graphics of the present embodiment and the conventional color will be described. This comparison shows the results of an experiment conducted on an example of a metal part among automobile parts. Table 1 shows the optical constants n and κ for certain wavelengths of the metal parts for automobiles. Here, silver plating used for grills and the like and gold plating used for emblems and the like were adopted.

[0112]

[Table 1]

FIGS. 8 and 9 show silver plating 11CR0, respectively.
1 is the spectral complex refractive index and the Fresnel reflectance. FIG.
0 and FIG. 11 show the spectral complex refractive index and Fresnel reflectance of the silver plating 11CR01, respectively.

[0114]

As described above, according to the present invention, the spectral distributions of the main light source and other light sources are determined based on the spectral solid angle reflectivity which is easily measured, and the object light is taken into consideration in consideration of internal absorption. Since the display data of the object is created from the specularly reflected light obtained based on the refractive index information including the internal absorption of the surface material, it can be used for objects having a regular reflectance different from that of glass, such as metals and glossy resins. Even if there is, there is an effect that it can be faithfully expressed.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing flow of a computer graphics device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a computer graphics device for reproducing an object color including a personal computer.

FIG. 3 is an image diagram for explaining gaze light;
(A) shows the reflection on the object surface, and (B) shows the reflection on the perfect diffuse reflection surface.

FIG. 4 is an explanatory diagram for explaining solid angle separation.

FIG. 5 is an explanatory diagram for explaining ray tracing.

FIG. 6 is a diagram for explaining Fresnel's equation.

FIG. 7 is an image diagram for explaining spectral solid angle reflectance.

FIG. 8 is a diagram showing characteristics of optical constants related to a complex refractive index.

FIG. 9 is a diagram showing characteristics related to the reflectance of Fresnel.

FIG. 10 is a diagram showing characteristics of optical constants related to a complex refractive index.

FIG. 11 is a diagram showing characteristics related to the reflectance of Fresnel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Keyboard 12 Computer main body 14 CRT 16 Personal computer

Claims (3)

[Claims] 1. A spectral solid angle reflectance of an object is input, and a spectral distribution of a main light source illuminating the object is determined based on the spectral solid angle reflectance, and a spectral distribution of another light source other than the main light source is obtained. The refractive index information including the internal absorption of the surface material of the object is input, and the spectral distribution of the specularly reflected light is determined using the refractive index information.The calculated spectral distribution of the main light source, the spectral distribution of the other light source and An object image display method, comprising: creating display data of the object based on a spectral distribution of specular reflection light; and displaying an image of the object based on the display data. 2. The method according to claim 1, wherein the refractive index information includes a complex refractive index including a real part representing a refractive index of a surface material of the object and an imaginary part representing an internal absorption of the surface material. 2. The object image display method according to 1. 3. The complex refractive index according to claim 2, wherein the relationship between the incident angle of light and the phase difference between the s-wave and the p-wave of polarized light is determined in advance, and the complex refractive index is determined based on the relationship. Object image display method.