JP2003331318A - Object data generator - Google Patents

Abstract

(57) [Problem] To appropriately set color data and reflection characteristic data for minute elements constituting three-dimensional shape data with simple and small work, and to faithfully reproduce color and texture. SOLUTION: Three-dimensional shape data in which color data is set in advance to minute elements is input to minute element selection means 12, and among minute elements constituting the three-dimensional shape data, minute rays in which light is vertically incident are included. Select an element as a representative microelement. The reflection characteristic data setting means 13 sets the reflection characteristic data for the representative microelement. The microelement grouping means 14 compares the color data of the representative microelement with the color data of the surrounding microelements, and if the hue values are substantially equal, puts them into the same group. Data duplication means 1
Reference numeral 5 copies and sets the color data and the reflection characteristic data set as the representative minute elements in all minute elements constituting the group. The generated data is sent to the stereoscopic image generation device 22 and output from the result output device 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object data generating apparatus for generating data used for drawing a three-dimensional image of an object on a two-dimensional plane, and more particularly to an apparatus for faithfully reproducing the color and texture of the surface of an object. Regarding

[0002]

2. Description of the Related Art In recent years, the speeding up of workstations and personal computers has made it possible to generate three-dimensional computer graphics (hereinafter referred to as three-dimensional CG) without using expensive equipment. Therefore, three-dimensional CG has begun to be used in fields other than movies and commercial production. For example, it is a virtual store or museum provided on the network. In stores and museums provided on these networks, the following work is performed in order to create a three-dimensional CG of a product or a relic (hereinafter collectively referred to as an object). (1) As shown in FIG. 14, an actually existing capture target object 100 is read by a three-dimensional scanner main body 101 such as a range finder, or from a developed view of the object,
Generate three-dimensional shape data of the object. (2) In order to determine the surface color of the generated three-dimensional shape data, as shown in FIG. 15, the object is photographed by a digital camera or the like, and the generated images 1 and 2 are the three-dimensional obtained in (1) above. It is assigned to each surface of the shape data and used as the surface color data.

[0003]

However, the conventional method has the following two problems. The first is for each minute element (polygon, voxel, etc.) of 3D shape data,
This is a problem in which it is impossible to set reflection characteristic data such as a reflection model representing a reflection method of an object and attribute values accompanying the reflection model. In a digital camera, when a certain part reflects or emits red light, that part outputs an image as "red". However, it is not possible to record what kind of material the red part is made of. For example, it is impossible to determine whether the part is a metal painted in red, a paper printed in red, or a plastic mixed with a coloring material that develops red. Therefore, although color data can be set for each minute element, reflection characteristic data cannot be set or default settings remain. If the reflection characteristic data is not set, the three-dimensional CG cannot be generated. Further, when the default setting remains as it is, for example, when the default setting is uniform diffusion, both the metal and the other material show the reflection characteristic similar to that of the matte plastic, which is an unnatural result. Either way, you will not get a satisfactory result.

The second problem is that the conditions under which an image is taken remain fixed. For example, when an object is photographed with a spotlight, the part where the light is strongly illuminated becomes brighter than the surroundings. When this is assigned to a three-dimensional shape model to generate a three-dimensional CG, this brightened portion remains bright regardless of the light source setting at the time of generating the three-dimensional CG. In other words, it looks as if the object had it from the beginning.

The above two problems are, for each microelement, the color of the color emitted when light is vertically incident on the material of the portion where the microelement is located (hereinafter referred to as the material represented by the microelement). It is possible to solve by setting the data and the reflection characteristic data of the material one by one. However, the number of minute elements forming the three-dimensional shape data is usually very large, and the work of setting values for all the minute elements is a very troublesome operation. The object of the present invention is to solve the above problems by setting appropriate color data and reflection characteristic data for minute elements that constitute the three-dimensional shape data with a simple and little work so as to faithfully match the color and texture of the object surface. It is to reproduce.

[0006]

In order to achieve the above-mentioned object, in the present invention, 3 composed of a plurality of minute elements is used.
In the object data generation device 10 for generating data used for drawing a three-dimensional image of an object on a two-dimensional plane according to the dimensional shape data, the color data set for the minute elements, and the reflection characteristic data, as shown in FIG. As shown, the three-dimensional shape data inputting means 11 for inputting the three-dimensional shape data in which the color data is set in advance in the minute elements, and the light entering vertically in the minute elements constituting the three-dimensional shape data A minute element selecting means 12 for selecting a minute element as a representative minute element, a reflection characteristic data setting means 13 for setting reflection characteristic data to the representative minute element, color data of the representative minute element, and a minute amount around the representative minute element. Compare with the color data of the element,
When the hue values are substantially the same, the minute element grouping means 14 that collects the same group, and the color data and the reflection characteristic data set as the representative minute elements are copied and set to all the minute elements that form the group. Data duplication means 15 is provided.

The minute element grouping means 14 extracts the brightest color data among the color data set for all the minute elements constituting the three-dimensional shape data, and the brightest color data with the representative minute element color data. On a plane surrounded by three straight lines, a straight line connecting color data, a straight line connecting color data of the representative microelements and black color data, and a straight line connecting the brightest color data and black color data, The minute elements having the color data positioned so as to be almost overlapped are put together in the same group. Further, the minute element selection means 12 is a three-dimensional shape data pre-display means for displaying a three-dimensional frame image of an object according to the three-dimensional shape data, and a position designation means for indicating a certain point in the displayed image. Further, when the minute element is displayed at the position designated by the position designation means, the minute element is set as the selected minute element. Further, the minute element selecting means 12 selects a plurality of minute elements from the three-dimensional shape data, and selects a minute element having color data with the highest saturation from the selected plurality of minute elements. , As a representative minute element.

In the minute element grouping means 14 of the object data generating device, when performing grouping, the color data assigned to each minute element is referred to. However, the determination as to whether or not to add to the group cannot be made based on the difference between the color data of the representative minute element and the color data of the minute element being judged. This is because the color of the material changes depending on how the light hits and is not fixed. However, for almost all substances, possible color data can be calculated if the illumination conditions and observation conditions are determined. For example, according to IPSJ Transactions, Vol. 34, No. 2, "Realistic Generation and Evaluation of Object Color in Three-Dimensional Space", inhomogeneous objects (most objects such as plastic and tree leaves are applicable) The possible colors can be expressed as in the following Expression 1 using the notation based on the spectral distribution.

[0009]

[Equation 1]

In the above equation, the first term on the right side represents the color due to diffuse reflection, and the second term represents the color due to specular reflection. Thus, for an inhomogeneous object, color is determined by the sum of diffuse and specular reflection. Also important is that the specular reflectance Ss of the object is not a function of wavelength λ. This means that the color of specular reflection matches the color of the illumination light. Based on the above, if Equation 1 is rewritten, Equation 2 is obtained.

[0011]

[Equation 2]

When the range of colors that can be taken by an inhomogeneous object is represented in the XYZ color space according to the above equation 2, it becomes as shown in FIG. In this way, the range of possible colors of an inhomogeneous object is specular reflection color 1, black 2, diffuse reflection color 3 when light is vertically incident on the object surface, and color 1 and color 3 are added together. It becomes a plane 4 surrounded by four points of color 6. Of these, the color 1 of specular reflection is equal to the color of the light source, so the line connecting the color 1 of specular reflection and the black 2 overlaps the achromatic axis 5. Therefore, it can be seen that the plane 4 is completely included in one of the equal hue planes radiating from the achromatic axis, and the surface color of the heterogeneous object has the same hue value regardless of the environmental conditions. Note that specular reflection is often much higher in intensity than diffuse reflection, so that color 1 and color 6 are almost the same color. Therefore, the possible color range of the inhomogeneous object can be approximated to the plane 7 surrounded by the colors 1, 2, and 3, as shown in FIG. Next, according to the above document, the color of the metal surface, which is a representative object other than the inhomogeneous object, is expressed by Equation 3.

[0013]

[Equation 3]

Further, according to the above-mentioned document, it is stated that, in an arbitrary object, when F (π / 2, λ) = 1, that is, when illumination light is horizontally incident on a metal, the color of the reflected light becomes equal to the incident light. There is. By rewriting Equation 3 based on this condition, Equation 4 is obtained.

[0015]

[Equation 4]

According to the equation (4), the possible range of the metal color is expressed in the XYZ color space as shown in FIG. in this way,
The possible range of the color of the metal is a plane 14 surrounded by three points: a color 11 when light is horizontally incident on the metal, a black 12 and a color 13 when light is horizontally incident on the metal. . Of these, the color 11 is the same as the color of the light source, so the line connecting the colors 11 and 12 overlaps the achromatic axis 15. Therefore, plane 1
4 is completely included in one of the equal hue planes that radiate from the achromatic axis. Therefore, the color of the surface of a certain metal is
It will have the same hue value regardless of the environmental conditions.

Therefore, the minute element grouping means 14
Then, when extracting the material represented by the representative minute element and the minute element representing the same material, the hue values of the color data of both are compared, and if they are substantially equal, they are grouped as the same material. As mentioned above, in the case of non-homogeneous objects that occupy most of objects and metals that are typical of other objects,
The hue value of the surface color data does not change regardless of the environment. Therefore, by referring to this hue value, it is possible to group minute elements that represent the same material without omission. This is a simple calculation that just compares the hue values, so
Processing can be performed at high speed.

Further, the minute element grouping means 1 of the present invention
In step 4, all the color data of all the minute elements are searched, and the color data with the highest brightness is extracted. When photographing an object with a digital camera or the like, some kind of illumination is always applied, and a highlight portion is formed on the surface of the object accordingly. In most cases, the highlight part represents the color of the lighting itself. Therefore, the plane created by connecting the color data, the black color data, and the color data of the representative microelements matches the area where the color of the object changes. Therefore, when it is determined whether or not a certain minute element represents the same material as the representative minute element, whether or not it is included in the plane defined by these three data, only the hue values are compared. It is possible to make a more accurate determination than to do. Therefore, it is possible to perform accurate grouping without omission and without erroneous addition.

Further, in the minute element selection means 12 of the present invention, when selecting a minute element, the three-dimensional shape of the object is displayed on the display means such as a CRT display based on the three-dimensional shape data inputted previously. Display the wireframe image shown. Then, the position specifying means such as a pointing device is used to point and select the minute element in the wire frame image of the displayed object. Since the work can be done visually, it is possible to easily select the minute element desired by the operator. Further, in the minute element selecting means 12 of the present invention, a plurality of minute elements are selected, and the minute element having color data with the highest saturation is selected as the representative minute element. Even in the case of minute elements representing the same material in both heterogeneous substances and metals, color data changes depending on the environmental conditions of the minute elements. Therefore, there is a possibility that a single selection cannot select a micro element located in a portion where the illumination light vertically strikes, which is a condition of the representative micro element.
In a certain material, the part where the illumination light strikes vertically is the part where the saturation is highest. for that reason,
When selecting a representative microelement, select a plurality of microelements and search for the color data with the highest saturation to find a microelement that meets the necessary conditions as a representative microelement. It can be an element.

[0020]

1 is a block diagram of an embodiment of the present invention. In FIG. 1, a portion 10 surrounded by a dotted line is an object data generation device, and devices outside the frame of the dotted line operate together with the object data generation device to capture and output an object. The capture device 21 generates three-dimensional shape data with color data. The capture device 21 has conventionally been an object 3
It is a three-dimensional scanner that has been used to acquire a three-dimensional shape, with a function for adding a color value added. The three-dimensional shape data with color data captured by the capturing device 21 is passed to the object data generating device 10.

As described above, the object data generating device 10 includes the three-dimensional shape data inputting means 11 with color data, the microscopic element selecting means 12 for selecting the microscopic element on which light is vertically incident as a representative microscopic element, Reflection characteristic data setting means 13 for setting reflection characteristic data to the representative minute element,
When the hue values of the representative minute elements are compared with the color data of the minute elements around the representative minute elements and the hue values are substantially equal to each other, the minute element grouping means 14 that collects them as the same group,
The data duplication unit 15 is configured to copy and set the color data and the reflection characteristic data set as the representative microelements to all the microelements constituting the group, and as described above, the grouped microelements are The color data and the reflection characteristic data set in the representative minute element are copied and set, and the three-dimensional shape data with the color data and the reflection characteristic data is generated. The three-dimensional shape data with color data and reflection characteristic data set by the object data generation device 10 is sent to the three-dimensional image generation device 22 to generate a three-dimensional CG. The generated three-dimensional CG is sent to and output by the result output device 23 such as a CRT display or a printer.

The object data generating device 10, the three-dimensional image generating device 22, the result output device 23, etc. are composed of a CPU, a memory,
It can be realized by a processing device such as a personal computer including an external storage device, a keyboard, a mouse, a CRT display, an input / output device such as a printer, and a communication control device.
A program for generating the three-dimensional shape data with the color data and the reflection characteristic data, a program for generating the three-dimensional CG, and the three-dimensional shape data to be processed are stored in the external storage device, etc. The program and the like are stored in the memory, and the generation process of the three-dimensional shape data with the color data and the reflection characteristic data and the generation process of the three-dimensional CG are performed.

The processing in each section of the embodiment shown in FIG. 1 will be described in detail below. (1) Capture Device The capture device 21 generates three-dimensional shape data with color data. The capture device 21 is a three-dimensional scanner that has been conventionally used to acquire the three-dimensional shape of an object, and a device that adds a color value to the three-dimensional shape data. Details of the three-dimensional shape data with color data captured by the capturing device 21 are shown in FIGS. 3 with color data
The dimensional shape data is composed of two databases as shown in FIG. The first is surface coordinate data having coordinate values in a three-dimensional space (x, y, z) as shown in FIG. The second is, as shown in FIG.
It is minute element data having the number of surface coordinates of the four corners of the minute element and the color data of the minute element. The surface coordinate data shown in FIG. 5 (a) is the x-axis, y-axis for the object to be captured.
The axes and z axes are set, and the positions of certain parts of the surface of the object with respect to the xyz axes are listed. The surface coordinate data depends on the size and shape of the object, but is usually a large number of hundreds to tens of thousands. Further, it is general that the portion where the shape changes drastically becomes dense and the portion where the shape changes gently becomes sparse.

The minute element data shown in FIG. 5B represents a minute surface portion of the object surrounded by the above surface coordinates. This data is, as a value, the number of the surface coordinates surrounding the minute element and the color data of that portion (X in this embodiment).
YZ value). This color data is used in the image generated by shooting an object captured by a digital camera,
It is the color data of the pixel corresponding to the position of the minute element. FIG. 6 shows the surface coordinates and a diagram of the minute elements.
A method of adding color data to minute elements in the capture device 21 will be described. First, as shown in FIG. 7A, the acquisition target object 100 is scanned by a three-dimensional scanner to generate three-dimensional shape data 110. Next, as shown in FIG. 7B, from the image 111 generated by capturing the capture target object 100 with a digital camera, the part 112 in which the object is captured is hollowed out to generate the pasting area image 113. Attached area image 11
As shown in FIG. 8C, 3 is 114 in the same figure in accordance with the element of the surface of the three-dimensional shape data to be pasted.
It is divided as shown in. Finally, as shown in FIG. 8D, the color data of each part of the divided image 114 is used as the color data of the corresponding minute element of the three-dimensional shape data 115. The three-dimensional shape data with color data obtained as described above is passed from the capturing device 21 to the three-dimensional shape data input means 11 of the object data generating device 10.

(2) Minute element selection means Three-dimensional shape data input means 11 is provided with the above-mentioned color data-added means 3
The dimensional shape data is passed to the minute element selection means 12. Figure 9
FIG. 3 is a block diagram showing the details of the minute element selecting means 12. As shown in the figure, the minute element selection means 12 is a three-dimensional shape data pre-display means 12a for drawing the shape of an object and the position of each minute element on a display device in accordance with the three-dimensional shape data with color data. The position specifying means 12b for allowing the operator to select a plurality of minute elements on the three-dimensional shape data by a pointing device or the like, and the minute element having the most saturated color data is selected from the selected minute elements. It is composed of the representative minute element determining means 12c. Upon receiving the three-dimensional shape data with color data, the minute element selection means 12 first passes this data to the three-dimensional shape data pre-display means 12a. As shown in FIG. 10, the three-dimensional shape data pre-display means 12a is a CRT.
The display device 121 such as a display has 3 color data
A wire frame image 123 in which the shape of the object and the position of each minute element are drawn according to the dimensional shape data is displayed. Then, the three-dimensional shape data preliminary display means 12a is
At which position (or not) is each minute element displayed on the screen of the display device 121?
The display position information on the screen of the minute element, which indicates, is passed to the position specifying means 12b.

The position specifying means 12b allows the operator to select a plurality of minute elements for the same material portion of the target object. Specifically, the cursor 129 is moved according to the movement of the pointing device 125 operated by the operator. Then, the button 1 attached to the pointing device 125
The display device 12 of the cursor 129 when 27 is imprinted
Get the position at 1. Next, the minute element selected by the operator is specified from the display position information of the minute element and the cursor position when the button is impressed, and the number of the minute element is recorded. This operation is repeated a plurality of times according to the operator's request, and each minute element number is recorded. Then, the numbers of the selected plurality of minute elements are sent to the representative minute element determination means 12c. The representative minute element determining means 12c selects a minute element having color data with the highest saturation from the selected plurality of minute elements. The saturation value C ^* is obtained by the following equation 5 when the color data of the light source is the XYZ value (Xw, Yw, Zw) and the color data of each minute element is the XYZ value (Xs, Ys, Zs).

[0027]

[Equation 5]

The saturation values C ^* of all the minute elements selected by the above equation 5 are calculated, and the minute element having the highest saturation is determined as the representative minute element. In this embodiment, the XYZ value is once converted into the L ^* u ^* v ^* value to obtain the chroma value C ^* _uv , and this value is used as the saturation value. However, the XYZ value is L ^* a ^* b.
^The chroma value C ^* _ab may be obtained by converting the value into a ^* value, and this value may be used as the saturation value. The representative minute element number obtained as described above is sent to the minute element grouping means 14.

(3) Microelement grouping means The microelement grouping means 14 extracts all microelements of the same material as the material represented by the representative microelement. The microelements of the same material as the representative microelements have the same hue value as the color data of the representative microelements, and the colors included in the plane surrounded by the color data of the illumination, the black color data, and the color data of the representative microelements. Have data. Therefore, the color data of the representative microelements are compared with the color data of the other microelements one by one, and the microelements that satisfy the conditions are grouped as microelements that represent the same material as the representative microelements. First, the hue values are compared. The formula for calculating the hue value h (degrees) from the XYZ values is as the following formula 6.

[0030]

[Equation 6]

If the hue values of the representative microelements and the color data of the microelements are compared, and the difference is 5 degrees or more, and it is determined that the hue values are different even if an error is taken into consideration, the microelements are the representative microelements. It does not belong to the group because it represents a different material. For the microelements whose hue values are judged to be substantially equal to the representative microelements, further judgment is carried out. That is, as shown in FIG. 11, the color data 163 of the minute elements is
However, the black color data 155 and the representative microelement color data 15
If it is included in the region 161 above the straight line 157 connecting 1 and below the straight line 159 connecting the color data 151 of the illumination and the color data 151 of the representative minute element, the minute element is made of the same material as the representative minute element. It can be judged that it represents. The values of the color data of the representative minute elements are XYZ values (Xr, Yr, Z
y), the value of the color data of the minute element for which the determination is made is XY
Z values (Xs, Ys, Zs), values of illumination color data are XY
Z value (Xw, Yw, Zw), the value of black color data is XYZ
If the value is (0, 0, 0), it can be determined that the representative minute element and the minute element represent the same material if the following Expression 7 is satisfied.

[0032]

[Equation 7]

This determination is performed for all the minute elements, and the minute element numbers of the minute elements that represent the same material as the representative minute element are collected as a group. The collected data is sent to the data duplication means as a group microelement database.

(4) Reflection Characteristic Data Setting Unit The reflection characteristic data setting unit 13 allows the operator to input the reflection characteristic data of the material represented by the minute elements included in the group. The number of reflection characteristic data will be enormous if exact coincidence with the real thing such as the reflection model type and its associated coefficient is sought. In this embodiment, as an example, a case where only the reflection model type is input as the reflection characteristic data will be described. The reflection model of an object is generally
There are the following: Lambert model (matte inhomogeneous object) Phong model (shiny inhomogeneous object) Cook trans model (metal) Specifically, a reflection model selection window as shown in FIG. 12 is displayed on the display device 121. Determine the reflection characteristic data of the group. The determined reflection characteristic data is sent to the data copying means 15.

(5) Data duplicating means The data duplicating means 15 sets the color data of the same value as the color data of the representative microelements to the microelements contained in the group microelement database. Further, the reflection characteristic data sent from the reflection characteristic data setting means 13 is set to the reflection characteristic data of the minute elements. In FIG. 13, as an example, the minute element number 3 is selected as a representative minute element, the reflection data of this minute element is set as a phon model, and the minute element numbers 1, 2, and
The modified minute element data when 4 was included is shown. The color data and the reflection characteristic data are appropriately set for the minute elements included in the group by the minute element selecting means 12 to the data copying means 15. further,
When there is a minute element whose value is not set in the reflection characteristic data in the three-dimensional shape data, the minute element selecting means 12
Repeat a series of operations from to until there are no small elements for which values are not set. When the reflection characteristic data is set for all the minute elements, the completed three-dimensional shape data with color data and reflection characteristic data is sent to the stereoscopic image generation device 22.

(6) Stereoscopic Image Generating Device and Result Outputting Device The stereoscopic image generating device 22 is generally commercially available software such as rendering software, shading software or renderer. This device takes in three-dimensional shape data with color data and reflection characteristic data, and uses a ray tracing method or the like to generate a three-dimensional CG.
The generated three-dimensional CG is output from the result output device 23 such as a CRT display or a printer.

[0037]

As described above, according to the present invention,
Appropriate color data and reflection characteristic data can be set to the minute elements forming the three-dimensional shape data with a simple and small operation, and the color and texture of the object surface can be faithfully reproduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration and a data flow of an embodiment of the present invention.

FIG. 2 is a diagram showing a possible color range of an inhomogeneous object.

FIG. 3 is a diagram showing an approximate range of colors of an inhomogeneous object.

FIG. 4 is a diagram showing a possible color range of a metal color.

FIG. 5 is a diagram illustrating an example of three-dimensional shape data with color data.

FIG. 6 is a diagram specifically illustrating a minute element and surface coordinates surrounding the minute element.

FIG. 7 is a diagram (1) showing an example of a method of assigning color data to minute elements.

FIG. 8 is a diagram (2) showing an example of a method of assigning color data to minute elements.

FIG. 9 is a detailed block diagram of the minute element selecting means of the embodiment of the present invention.

FIG. 10 is a diagram concretely showing a three-dimensional shape data pre-display means and a position designation means.

FIG. 11 is a diagram showing a region taken by color data in the case where the minute element is the same as the material of the representative minute element.

FIG. 12 is an example of a dialog displayed on a display device when an operator inputs a reflection model.

FIG. 13 is a diagram showing minute element data (one of data forming three-dimensional shape data) in which reflection characteristic data is input and color data is also reset.

FIG. 14 is a diagram illustrating reading of three-dimensional data by a general three-dimensional scanner.

FIG. 15 is a diagram showing the concept of assigning an image to three-dimensional data.

[Explanation of symbols]

10 Object data generator 11 Three-dimensional shape data input means 12 Minor element selection means 12a 3D shape data pre-display means 12b Position designation means 12c Representative minute element determining means 13 Reflection characteristic data setting means 14 Small element grouping means 15 Data replication means 21 Capture device 22 Stereoscopic image generator 23 Result output device

Claims (5)

[Claims] 1. Use for drawing a three-dimensional image of an object on a two-dimensional plane according to three-dimensional shape data composed of a plurality of microelements, color data and reflection characteristic data set for the microelements. An object data generation device for generating data, comprising: three-dimensional shape data input means for inputting three-dimensional shape data in which color data is set in advance for minute elements; and representative minute elements from the three-dimensional shape data. The minute element selection means to be selected, the representative minute elements and the color data of the minute elements around them are compared, and if the hue values are almost the same, the minute element grouping means to group them as the same group, and the representative minute elements , When the reflection characteristic data is set, copy and set the color data and the reflection characteristic data set for the representative minute elements to all the minute elements that make up the group. Object data generating apparatus characterized by having a data replication means. 2. The minute element grouping means extracts the brightest color data from the color data set for all the minute elements constituting the three-dimensional shape data, and extracts the color data of the representative minute elements. A plane surrounded by three straight lines: a straight line connecting the brightest color data, a straight line connecting the color data of the representative minute elements and black color data, and a straight line connecting the brightest color data and black color data 2. The object data generation device according to claim 1, wherein the minute elements having color data positioned so as to substantially overlap each other are grouped into the same group. 3. The three-dimensional shape data pre-display means for displaying a three-dimensional frame image of an object in accordance with the three-dimensional shape data, and a minute element in the displayed three-dimensional frame image. 3. The object data generation device according to claim 1 or 2, further comprising: a representative minute element determining means for determining a representative minute element from the instructed minute elements. 4. The representative minute element determining means selects a plurality of minute elements from the three-dimensional shape data, and has color data with the highest saturation among the selected plurality of minute elements. The object data generation device according to claim 3, wherein the minute element is a representative minute element. 5. Data for drawing a three-dimensional image of an object on a two-dimensional plane according to three-dimensional shape data composed of a plurality of minute elements and color data and reflection characteristic data set for the minute elements. An object data generation program to be generated, wherein when the three-dimensional shape data in which color data is set in advance is input to the minute elements, the program selects a representative minute element from the three-dimensional shape data. When the color values of the representative microelements and the microelements around them are compared, and the hue values are almost the same, grouping processing is performed to group them as the same group, and when the reflection characteristic data is set, the above group is configured. The color data and the reflection characteristic data set as the representative minute elements are copied to all the minute elements to be executed by the computer. Object data generation program characterized.