JPH11203498A - Method and device for generating texture coordinate by using normal vector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a texture coordinate generating device using a normal vector capable of reducing the recalculation frequency of texture coordinate data due to a change in a visual point even when a plane-like texture image is stuck to a three-dimerasinal(3D) graphic. SOLUTION: A coordinate data input means 11 inputs the coordinate data of a polygon to a coodinate data transformation means 12X which transforms the polygon coordinate data into texture coodinate data and a normal data input means 13 inputs the polygon coordinate data to a coordinate correction means 14. The means 14 corrects the texture coordinate data by using the vector value of normal data of the polygon so that the interval ratio of respective points on a 3D graphic is close to an interval ratio of respective stores projected to a texture image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional graphics process, in which the texture coordinate data converted from the coordinates of a polygon (polyhedron) is converted to the interval ratio of each point on the three-dimensional figure by the vector value of the normal data of the polygon. And a texture coordinate generation method and apparatus using a normal vector that corrects in a direction in which an interval ratio after being projected on a texture image becomes closer.

[0002]

2. Description of the Related Art In computer graphics, when a three-dimensional figure is displayed using polygons, texture mapping is often used to realistically express the texture of the surface. Regarding this texture mapping, for example, Japanese Unexamined Patent Publication No. 05-46775 discloses that the resolution of a texture is determined in accordance with an assumed relative positional relationship between a camera screen and a subject, and is defined as a vector value function on a two-dimensional plane. It is disclosed that a texture having a resolution determined from a generated texture pattern is generated, and a captured image assumed to be captured on a camera screen of a subject coordinated with the generated texture is generated.

Japanese Patent Application Laid-Open No. 06-176129 discloses that a texture image for mapping is superimposed on a development view obtained by developing a plurality of polygons constituting a three-dimensional shape of an object surface, and the development view and the texture image are compared with each other. It is disclosed to interactively perform the registration of the images and produce a projection image based on the mapped development view. Further, Japanese Patent Application Laid-Open No. 09-190550 discloses a polygon that captures a set of images covering the entire periphery of an observation position in a three-dimensional space and recently expresses the shape of a sphere centered on the observation position. It is disclosed that a plane model is created, and a texture image to be attached to each polygon plane of each polygon plane model of the polygon plane model is generated based on the captured image group.

[0004] Texture mapping is a technique for expressing a pattern by pasting image data in which irregularities and patterns are drawn in advance on polygons, instead of expressing fine irregularities and patterns on the surface of a figure by subdivided polygons. is there. When expressing the texture of the surface of a three-dimensional figure by performing texture mapping, it is necessary to give texture coordinates to vertices of a polygon to be written. Further, it is necessary to prepare a plurality of pieces of texture data to be pasted according to the viewpoint overlooking the three-dimensional figure.

[0005] These texture images are generally generated from planar data such as photographs, and the pasting of the texture is performed as if the texture image was projected onto a figure. As described above, when a planar texture image is used, there is a problem that the texture image on the side surface of the graphic is distorted when the starting point for looking over the graphic is changed. As a method for solving this, a method of preparing a large number of texture images corresponding to individual cases in which the viewpoint overlooking the figure is changed, a method of preparing a three-dimensional texture image using a three-dimensional digitizer, or a method of 08-24949
As described in Japanese Patent Laid-Open No. 1 (Kokai) No. 1, a method of giving a thickness to a texture image has been proposed.

[0006]

However, the above-mentioned prior art has two problems as described below.
That is, the first problem is that the cost of generating the texture image data itself increases with the increase in the number of three-dimensional figures to be drawn due to the recent demand for three-dimensional graphics, The cost of generating the texture image data increases. The second problem is that it is based on a flat texture image,
Since there is always a viewpoint overlooking the figure in a direction parallel to the plane, the distortion of the texture image data due to the change of the viewpoint is large. However, this does not apply to the case where a three-dimensional texture image is created in the related art.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. Even when a planar texture image is pasted on a three-dimensional figure, the frequency of recalculation of texture coordinate data due to a change in viewpoint is changed. Coordinate generation method using a normal vector, which can reduce the number of texture image data required in the three-dimensional graphics system, and can reduce the capacity of the texture data storage unit in the three-dimensional graphics system. The purpose is to provide.

In order to achieve the above object, a texture coordinate generation method using a normal vector according to the present invention converts polygon coordinate data into texture coordinate data, and converts the texture coordinate data into a vector of polygon normal data. The value is corrected in such a direction that the interval ratio of each point on the three-dimensional figure and the interval ratio after being projected on the texture image become closer.

A texture coordinate generating apparatus using a normal vector according to the present invention comprises: coordinate data converting means for converting coordinate data of a polygon input by coordinate data input means into texture coordinate data; And inputting the texture coordinate data to the interval ratio of each point on the three-dimensional figure and the texture image by the vector value of the normal data of the polygon input by the normal data input means. And a coordinate correcting means for correcting the distance ratio after the projection becomes closer.

According to the texture coordinate generation method using normal vectors of the present invention, coordinate data of a polygon is converted into texture coordinate data. With the texture coordinate data as it is, the resulting image in which the texture image is pasted on the larger polygon, either the direction of the polygon on the three-dimensional figure or the direction of the texture image, is compared with the polygon closer to the texture image. Causes large distortion.
Therefore, the texture coordinate data is corrected using the vector values of the normal data of the polygon so that the interval ratio of each point on the three-dimensional figure and the interval ratio projected on the texture image become closer, so that less texture original data is obtained. Texture image data that can be stuck all over the three-dimensional image is generated from the image.

According to the texture coordinate generating apparatus using normal vectors of the present invention, when the coordinate data of the polygon is input to the coordinate data converting means by the coordinate data inputting means, the coordinate data converting means sets the normal line of the polygon. Convert the data to texture coordinate data. If the texture coordinate data converted by the texture coordinate data is used as is, the resulting image obtained by pasting the texture image on the polygon, which is either the direction of the polygon on the three-dimensional figure or the direction of the texture image, is the direction of the texture image. Large distortion occurs as compared to polygons close to. In order to eliminate this distortion, normal line data of the polygon is input by the normal line data input means and output to the coordinate correction means. The coordinate correcting means converts the texture coordinate data converted by the coordinate data converting means into an interval ratio of each point on the three-dimensional figure using a vector value of normal data of the polygon and an interval ratio after being projected on the texture image. Is corrected so as to be closer to the original image, and texture image data that can be stuck all around the three-dimensional image is generated from the original texture image.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a texture coordinate generating apparatus using a normal vector according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment. In FIG. 1, the coordinate data input means 11 inputs coordinate data of a polygon to a coordinate data conversion means 12, and the coordinate data conversion means 12 converts the input coordinate data of the polygon into a predetermined means ( For example, a widely known high-speed conversion means includes a primary conversion, etc.), and the data is converted into texture coordinate data.

When converting the texture coordinates,
For example, when a primary transformation is used as the transformation means of the coordinate data, the texture image is placed on a virtual plane, and the three-dimensional figure is mapped on the plane by projection. If the texture coordinate data converted by the coordinate data converting means 12 is used as it is, an image obtained as a result of pasting the texture image on a polygon, which is either the direction of the polygon on the three-dimensional figure or the direction of the texture image, is larger. Large distortion occurs compared to a polygon close to the direction of the texture image. Therefore, when the figure is viewed from another viewpoint, unnaturalness is conspicuous. Therefore, it is necessary to recalculate the texture coordinates.

In the first embodiment, in order to reduce the frequency of recalculation of the texture coordinates, the texture coordinate data is corrected using the vector values of the normal data. This is one of the features of the embodiment. Therefore, the texture coordinate data converted by the coordinate data conversion means 12 is sent to the coordinate correction means 14, and the conversion formula data is also input to the coordinate correction means 14. Further, the normal data of the polygon is input to the coordinate correcting means 14 by the normal data input means 13.

The coordinate correcting means 14 corrects the texture coordinate data converted by the coordinate data converting means 12 by using the vector value of the normal data of the polygon. By using the value, the correction is made in such a direction that the interval ratio between the points on the three-dimensional figure and the interval ratio after being projected on the texture image become closer. In this way, it is possible to generate texture coordinate data that reduces the distortion of the texture image that is mapped to the side surface of the three-dimensional figure when using the linear transformation, and to reduce the number of texture images around the three-dimensional image from the fewer texture images. Since texture coordinate data that can be stuck all over can be generated, it is possible to suppress the frequency of recalculating the texture coordinate data when the viewpoint is changed.

Next, the internal configuration of the coordinate correcting means 14 will be described. FIG. 2 is a block diagram showing the configuration of the coordinate correcting means 14. The conversion formula data is inputted to the conversion formula storage means 21. The conversion formula storage means 21 stores a conversion formula for performing an appropriate correction conversion using a vector value of normal data on the texture coordinate data calculated using an appropriate conversion. The data is output to the correction calculating means 22. This conversion formula can be arbitrarily changed from outside.

The correction calculating means 22 receives texture coordinate data and vector values of polygon normal data in addition to the conversion formula stored in the conversion formula storage means 21. The correction operation unit 22 performs a correction operation for correcting the texture coordinate data by the vector value of the normal data using the conversion formula stored in the conversion formula storage unit 21. Correction calculation means 2
2 is output to the correction data output means 23.

Next, the operation of the first embodiment configured as described above will be described with reference to the flowchart of FIG. The description of this operation also serves as the description of the first embodiment of the texture coordinate generation method using the normal vector according to the present invention. First, the conversion formula data used for the correction calculation for the texture coordinate correction is input to the conversion formula storage unit 21 of the coordinate correction unit 14 (step A1). Next, the coordinate data of the polygon is inputted by the coordinate data input means 11 (step A2).
The coordinate data conversion means 12 is supplied with the coordinate data of the polygon as required by the coordinate data input means 11, and generates texture coordinate data by appropriate conversion (step A3).

Next, the normal data of the polygon is inputted by the normal data input means 13 (step A4), and is inputted to the correction calculating means 22 of the coordinate correcting means 14. The correction operation unit 22 performs the correction operation using the texture coordinate data generated by the coordinate data conversion unit 12, the normal data supplied from the normal data input unit 13, and the conversion formula supplied from the conversion formula storage unit 21. To correct the texture coordinate data (step A5), and output the corrected texture coordinate data to the correction data output means 23. The correction data output unit 23 outputs the corrected texture coordinate data in response to a request from outside the apparatus of the present invention (step A6), and determines whether the texture coordinates have been corrected for all polygons. Is determined (step A7).

If the result of this determination is that all polygons have not been processed, the process returns from step A7 to step A2. When the processing for all polygons is completed in step A7,
The processing of the apparatus of the present invention ends.

Next, the operation of the first embodiment will be described using a concrete example in comparison with a conventional example. FIG.
0 is a perspective view, and as shown by an arrow y1 in FIG.
FIG. 5 shows a schematic diagram of the texture pasting in a case where the cylinder 100 is looked down in the negative direction of the y-axis as an example.
(In the case of the present invention), as shown in FIG. 9 (in the case of the conventional example). In FIG. 9, it is assumed that a texture is pasted on a cylinder 100 having a radius r whose center axis coincides with the y-axis.
Since the same applies to the V coordinate, for simplification, only the U coordinate will be considered as the texture coordinate.

In FIG. 9, point A is a point on the Z-axis, and points B, C, and D are points rotated on the circumference of the cylinder 100 by 20 degrees from the center of the cylinder 100, respectively. In this case, for example, the U coordinate is converted to u
= X / r, and a conversion equation based on a normal vector N = (a, b, c) is assumed to be u1 here.
= × (a + 4) / 5 (step A1). The U coordinates before correction at points A, B, C, and D are 0, 0.232, 0.642, and 0.866, respectively (steps A2 and A3). The ratio of these intervals is 1: 0.877: 0.655, and the distortion of the texture image increases toward the end of the cylinder.
When the viewpoint is moved, the unnaturalness of the texture image becomes conspicuous, and it is necessary to recalculate the texture coordinates.

On the other hand, in the case of the first embodiment, the result of correcting the texture coordinate data by the normal vector is as shown in FIG. FIG. 5 is also a diagram when looking down in the negative direction of the Y-axis of the cylinder 100 shown in FIG. 4, as in the case of FIG. 9, and the points A, B, and The corrected U1 coordinates at point C and point D are 0, 0.296, 0.596, and 0.893, respectively.
(Step A4 and Step A5). The ratio of these intervals is 1.00: 1.00: 1.00,
The distortion has been corrected.

The result of this correction is output as required (step A6). Finally, a condition judgment is made as to whether or not processing has been completed for all polygons, and processing is performed for all polygons (step A7). With this correction result, the distortion of the texture image can be reduced when the viewpoint is moved, and the frequency of recalculation of the texture coordinates is reduced.

Next, a second embodiment of a coordinate generating apparatus using a normal vector according to the present invention will be described with reference to FIGS. FIG. 6 is a block diagram showing the configuration of the second embodiment. 6, in description of the configuration, portions corresponding to those in FIG. 1 are denoted by reference numerals in their forties, and the first digit is denoted by the same reference numeral, and redundant description is omitted.

As is clear from the comparison of FIG. 6 with FIG.
6, a normal data conversion unit 44 is newly added to the configuration of the first embodiment shown in FIG. The normal data conversion means 44 is for performing an appropriate conversion of the normal data of the polygon used for correcting the texture coordinate data before the correction processing. Further, the coordinate correction conversion means 45 is denoted by reference numeral 45, and the internal configuration of the coordinate correction conversion means 45 is the same as that of FIG. 2, and the parts corresponding to FIG. In the first digit, the same reference numerals are given and duplicate explanations are omitted.
Is added, the vector value of the converted normal data, which is the conversion result of the normal data conversion means 44, is used. Other configurations are the same as those of the first embodiment.

Next, the operation of the second embodiment will be described with reference to the flowchart of FIG. The description of this operation also serves as the description of the second embodiment of the texture coordinate generation method using the normal vector according to the present invention. First, the conversion formula data used for the correction calculation for the texture coordinate correction is input to the conversion formula storage means 51 of the coordinate correction means 45 (step B1). The coordinate data is input to the apparatus of the present invention by the coordinate data input means 41 (step B2).

The coordinate data converting means 42 receives the coordinate data from the coordinate data input means 41 as necessary, and generates texture coordinate data by appropriate conversion (step B3). Normal line data input means 4
3 to input to the apparatus of the present invention (step B)
4). The normal data conversion unit 44 receives the normal data from the normal data input unit 43 as necessary, and generates converted normal data by appropriate conversion (step B).
5).

The correction calculating means 52 receives the texture coordinate data generated by the coordinate data converting means 42, the vector value of the converted normal data supplied from the normal data converting means 44, and the conversion formula storing means 51. The correction of the texture coordinate data is performed by the correction operation using the converted equation, and the corrected texture coordinate data is output to the correction data output means 53 (step B6). The correction data output means 53 outputs the corrected texture coordinate data in response to a request from outside the apparatus of the present invention (step B7), and determines whether the texture coordinates have been corrected for all polygons. Is determined (step B8).

If the result of this determination is that processing has not been completed for all polygons, the processing procedure is returned from the processing step of step B8 to the processing step of step B2, and the same processing as described above is executed. . If the processing for all the polygons has been completed in the processing step of step B8, a series of processing steps in the apparatus of the present invention is completed.

[0031]

As described above, according to the present invention, the texture coordinate data obtained by converting the coordinate data of the polygon by the predetermined means is determined by the vector ratio of the normal data of the polygon to the interval ratio of each point on the three-dimensional figure. Since the distance ratio after projection on the texture image is corrected so that it becomes closer, even if the planar texture image data is pasted on a three-dimensional figure, the texture coordinate data associated with the change of the viewpoint is re-created. The calculation frequency can be reduced.
Accordingly, the angle of change of the viewpoint requiring new texture image data becomes larger than that of the conventional texture image pasting method, so that the required number of pieces of texture image data can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a texture coordinate generation device using a normal vector according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a coordinate correction unit in the texture coordinate generation device using the normal vectors of FIG. 1;

FIG. 3 is a flowchart showing an operation flow of the texture coordinate generation device using the normal vector of FIG. 1;

FIG. 4 is a perspective view of a cylinder to which texture pasting is applied by the coordinate correction unit of FIG. 2;

FIG. 5 is a schematic diagram of texture pasting for explaining a texture coordinate generating apparatus using a normal vector according to the present invention when looking down in the negative direction of the Y-axis of the cylinder shown in FIG. 4;

FIG. 6 is a block diagram illustrating a configuration of a second embodiment of a texture coordinate generation device using normal vectors according to the present invention.

FIG. 7 is a block diagram illustrating a configuration of a coordinate correcting unit in the texture coordinate generation device using the normal vectors of FIG. 6;

8 is a flowchart showing an operation flow of the texture coordinate generation device using the normal vector of FIG.

FIG. 9 is a schematic diagram of texture pasting for describing a conventional texture coordinate generation device when looking down in the negative direction of the Y axis of the cylinder shown in FIG. 4;

[Explanation of symbols]

11, 41 ... coordinate data input means, 12, 42 ... coordinate data conversion and conversion means, 13, 43 ... normal data input means, 14, 45 ... coordinate correction means, 21, 51 ... conversion formula storage means , 22, 52 ... Correction calculation means, 23, 5
3 ... Correction data output means, 44 ... Normal data conversion means.

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[Procedure amendment]

[Submission date] February 4, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 8

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 10

[Correction method] Change

[Correction contents]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005] These texture images are generally generated from planar data such as photographs, and the pasting of the texture is performed as if the texture image was projected onto a figure. As described above, when a planar texture image is used, there is a problem that the texture image on the side surface of the graphic is distorted when the viewpoint overlooking the graphic is changed. As a method for solving this, a method of preparing a large number of texture images corresponding to individual cases in which the viewpoint overlooking the figure is changed, a method of preparing a three-dimensional texture image using a three-dimensional digitizer, or a method of 08-24949
As described in Japanese Patent Laid-Open No. 1 (Kokai) No. 1, a method of giving a thickness to a texture image has been proposed.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. Even when a planar texture image is pasted on a three-dimensional figure, the frequency of recalculation of texture coordinate data accompanying a change in viewpoint is changed. And a texture coordinate generation method using a normal vector, which can reduce the number of texture image data required in a three-dimensional graphic system, and can reduce the number of required texture image data. The purpose is to do.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

Next, the operation of the first embodiment will be described using a concrete example in comparison with a conventional example. Figure 4 shows the cylinder 1
FIG. 5 is a perspective view of texture sticking, as shown by a thick line arrow in FIG. 4, taking a case where the cylinder 100 is looked down in the negative direction of the y-axis as an example. ) And FIG. 9 (in the case of the conventional example). In FIG. 9, it is assumed that a texture is pasted on a circle 100 having a radius r whose center axis coincides with the y-axis. Since the same applies to the V coordinate, for simplification, only the U coordinate will be considered as the texture coordinate.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

In FIG. 9, point A is a point on the Z axis, and points B, C, and D are points that are rotated on the circumference of the cylinder 100 by 20 degrees from the center of the circle note 100, respectively. . In this case, for example, the U coordinate is converted to u
= X / r, and a conversion equation based on a normal vector N = (a, b, c) is assumed to be u1 here.
= U × (a + 4) / 5 (step A1). The U coordinates before correction at points A, B, C, and D are 0, 0.232, 0.642, and 0.866, respectively (steps A2 and A3). The ratio of these intervals is 1: 0.877: 0.655, and the distortion of the texture image increases toward the end of the cylinder, so that the unnaturalness of the texture image is noticeable when the viewpoint is moved, Recalculation of texture coordinates is required.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

Next, a second embodiment of the texture coordinate generating apparatus using normal vectors according to the present invention will be described with reference to FIGS. FIG. 6 is a block diagram showing the configuration of the second embodiment. 6, in the description of the configuration, portions corresponding to those in FIG. 1 are denoted by reference numerals in their forties, and the first digit is denoted by the same reference numeral to avoid redundant description.

Claims (10)

[Claims] 1. After converting coordinate data of a polygon into texture coordinate data, the texture coordinate data is projected on a texture image by an interval ratio of each point on a three-dimensional figure by a vector value of normal data of the polygon. A texture coordinate generation method using a normal vector, wherein the texture ratio is corrected in a direction in which the interval ratio of the texture coordinates becomes closer. 2. The texture coordinate generation method using a normal vector according to claim 1, wherein the texture coordinate data is converted from coordinate data of a polygon by a primary conversion. 3. The texture coordinate data includes: a conversion formula for performing correction conversion on the texture coordinate data using a vector of normal data; texture coordinate data;
2. The method according to claim 1, wherein an interval ratio between each point on the three-dimensional figure and an interval ratio after being projected on a texture image are corrected by a vector value of normal data of a polygon. Texture coordinate generation method using the normal vector of. 4. The texture coordinate data is corrected in such a direction that the interval ratio between points on a three-dimensional figure and the interval ratio after being projected on a texture image become closer by a vector value of converted normal data of a polygon. 2. A texture coordinate generation method using a normal vector according to claim 1, wherein: 5. The texture coordinate data includes a conversion formula for performing correction conversion on the texture coordinate data by using a vector value of normal data, a texture coordinate data, and a vector value of converted normal data of a polygon. 2. A texture using a normal vector according to claim 1, wherein the correction is performed in such a manner that the interval ratio between the points on the three-dimensional figure and the interval ratio after being projected on the texture image become closer. Coordinate generation method. 6. A coordinate data converting means for converting coordinate data of a polygon inputted by a coordinate data input means into texture coordinate data; a normal data input means for inputting normal data of a polygon; Coordinates to be corrected in a direction in which the interval ratio of each point on the three-dimensional figure and the interval ratio after being projected on the texture image become closer according to the vector value of the normal data of the polygon input by the normal data input means. A texture coordinate generation device using a normal vector, comprising: a correction unit. 7. The texture coordinate generation device using normal vectors according to claim 6, wherein said coordinate data conversion means converts said coordinate data into texture coordinate data by a primary conversion. 8. A conversion formula storage means for storing a conversion formula for performing correction conversion on the texture coordinate data using a vector value of normal data,
Correction calculating means for inputting the conversion formula, the texture coordinate data, and the vector value of the normal data and performing the conversion to correct the texture coordinate data by the vector value of the normal data; and 7. The texture coordinate generating apparatus using a normal vector according to claim 6, further comprising: correction data output means for outputting texture coordinate data which has been corrected by a calculation means. 9. The coordinate correction means according to claim 6, wherein the vector ratio of the converted normal data of the polygon makes the interval ratio of each point on the three-dimensional figure closer to the interval ratio after being projected on the texture image. The texture coordinate generating apparatus using a normal vector according to claim 6, wherein the texture coordinate data is corrected. 10. A conversion formula storage means for storing a conversion formula for performing correction conversion on the texture coordinate data using a vector value of normal data, the conversion formula storage device, A correction operation unit that inputs the texture coordinate data and the vector value of the converted normal data, and corrects the texture coordinate data by the conversion by the vector value of the normal data; 7. A texture coordinate generating apparatus using a normal vector according to claim 6, further comprising correction data output means for outputting vertical texture coordinate data.