JPH0997343A - Method and device for texture data generation and computer controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate photography for preparing a texture source image and eliminate a waste when a necessary area is extracted from the texture source image. SOLUTION: A source image that a texture is based on is read in through an input/output interface (step S201) and the necessary area is specified on the texture source image that the texture is based on with feature points at sticking destination (step S202); and quadrangles encircling the specified area is generated according to a specific rule and the quadrangle of the least area among generated quadrangles is extracted (steps S203-S207). Then the image encircled with the extracted quadrangle is converted into a quadrangular image of desired size (steps S208-S212) and the specific area (feature points) is converted into an area on a rectangular image (step S213). The obtained rectangular image and data on the feature points specifying the area are outputted as texture data (step S214).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for generating texture data in computer graphics.

[0002]

2. Description of the Related Art 3 in Computer Graphics
As a method of drawing a three-dimensional scene, there is a method of preparing a surface pattern as texture data and pasting the texture data to shape data of a three-dimensional scene. An image obtained by shooting a natural image can be applied as the texture data.

As described above, when a natural image is used as texture data, there are conventionally two methods of generating the texture data as follows.

(1) An image is taken according to the shape and size of an image to be texture data to obtain an original texture image, and a point (vertex etc.) corresponding to the shape of the pasting destination.
Is set on the original texture image. Then, the image is pasted while associating the given point and the pasting point on the original texture image.

(2) A desired rectangle is set on the original image of the texture obtained by photographing, and a necessary area is cut out from the original texture image as a rectangle. The cut-out rectangular image is used as a texture original image and the image is pasted by the same procedure (setting and pasting of vertices) as in the above (1).

[0006]

However, the conventional texture data generation method described above has the following problems. First, in the above method (1), the object to be used as a texture must be photographed according to its shape and size. In other words, it is desirable to capture the image as large as possible while including the entire target to be used as the texture, and the image capturing cannot be performed easily. Here, the reason why the object used as a texture is photographed as much as possible is to improve the reproducibility of the details of the texture after pasting.

Further, for example, when an image of a flat surface is taken as an object of texture, if the image is taken from an oblique direction, the pattern of the surface appears to be partially shrunk in the result of the image pickup. Therefore, a high resolution is required to represent the details of the contracted portion, and the amount of texture data increases. Therefore, it is desirable to shoot from directly above the object used as a texture, which is another factor that makes shooting difficult.

Further, in the above method (2), the necessary area in the original image of the texture is not necessarily in the shape of a rectangle, so that there is a possibility that a lot of useless areas may be left. there were. Further, when the object used as the texture is photographed from an angle, the same problem as in the case of the above (1) occurs.

The present invention has been made in view of the above problems, and simplifies photographing when preparing a texture original image,
Another object of the present invention is to provide a texture data generation method and apparatus capable of eliminating waste (reducing unnecessary areas) when extracting a necessary area from a texture original image.

[0010]

The texture data generating apparatus of the present invention for achieving the above object has the following configuration. That is, a texture data generation device for generating texture data used for computer graphics, in which a designating unit designating a required region and a region designated by the designating unit are provided on a texture original image which is a basis of a texture. Generating means for generating a quadrangle surrounding the quadrangle based on a predetermined rule and extracting the quadrangle having the smallest area, and first converting an image enclosed by the quadrangle extracted by the generating means into a rectangular image of a desired size. Conversion means,
Second conversion means for converting the specified area specified by the specifying means into an area on the rectangular image, the rectangular image obtained by the first converting means, and the specified area obtained by the second converting means are shown. And output means for outputting information as texture data.

Preferably, the designating means designates a required area by designating a plurality of feature points representing the shape of the pasting image on the texture image, and the second converting means , Converting the plurality of feature points designated by the designation means into feature points at corresponding positions on the rectangular image. Since the feature points (vertices, control points, etc.) of the pasting destination are specified, it is not necessary to designate the feature points again for the obtained rectangular image, and the operability is improved. The operation was cumbersome because the rectangular image was cut out from the original texture image and the feature points were specified separately.

[0012] Preferably, the generating means forms a convex hull polygon surrounding the plurality of feature points, and has a minimum area of a quadrangle formed by a straight line including four sides of the convex hull polygon. Extract the quadrangle that becomes.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the schematic arrangement of a computer device according to this embodiment. In the figure, 101
Is a CPU and executes various processes including the procedure of the present embodiment. 102 is a memory, which is a ROM 102a, RA
Including M102b. The ROM 102a stores the control program executed by the CPU 101 and various data, and the RAM 1
02b provides a work area for the CPU 101 to execute various controls.

Reference numeral 103 denotes a storage device, which is composed of, for example, a hard disk or a floppy disk. Storage device 1
Various data such as texture original image data is stored in 03.

Reference numeral 104 denotes an input / output interface for inputting or outputting data to be processed from outside the device. For example, a texture original image obtained by shooting with a camera can be read by a scanner and can be captured via the input / output interface 104. A keyboard 105 is used for selecting data and inputting procedures. Reference numeral 106 is a pointing device for designating a pointing point on the display device, and is constituted by, for example, a mouse. A display device 107 displays a processing status, a processing result, a processing process, and processing data.

Next, the texture data generation processing of this embodiment, which is realized by the computer device having the above-mentioned configuration, will be described. FIG. 2 is a flowchart showing the procedure of the texture data generation process of this embodiment.

In step S201, the texture original image which is the source of the texture to be generated is read through the input / output interface 104 and stored in the storage device 103 as the texture original image. Here, the texture original image is a normal color or grayscale image containing a texture to be generated. Then, by the following processing, using the image data of a part of the area of the original texture image,
An image serving as texture data will be generated.

In step S202, an area required as texture data is designated on the original texture image. This step is performed by designating a plurality of points where the vertices and control points of the patch data (plane or curved surface) where the texture is pasted are located on the original texture image. This point is designated by displaying the original texture image stored in the storage device 103 on the display device 107 and using the mouse 106 on the display screen. Characteristic points such as designated vertices and control points are stored in the storage device 103 as designated point information data.

Next, in step S203, step S
A convex hull that encloses a region defined as required for the texture data is generated by the designated point on the texture original image designated by 202. For example, when the patch is a plane patch (polygon), a convex hull enclosing the specified point that is the vertex may be generated. In the case of a curved surface patch, for example, a control point that defines a curved surface to which a texture is to be attached is specified on the original texture image, and a convex hull enclosing the curved surface defined by the control point is generated. In this case, the control points are not always included in the convex hull. More specifically, the curved surface patch in the space defined by the control points is drawn on the plane of the original texture image, and the convex hull including the drawn curved surface patch is formed.

Next, in step S204, four sides are selected from the sides forming the convex hull generated in step S203. Then, in step S205,
A quadrangle is generated by a straight line including the selected four sides. At this time, a quadrangle that does not include the entire convex hull is excluded, and only a quadrangle that includes the entire convex hull is generated. If the area of the generated quadrangle is the smallest (the smallest that has been generated so far), the quadrangle is stored in the RAM 102b as the quadrangle S. In step S207, step S207 is performed for all combinations of four sides of the convex hull.
It is checked whether the processes of 204 to S206 have been performed, and these steps are performed for all combinations of four sides. This makes it possible to generate the quadrangle S having the smallest area among the quadrangles including the convex hull. The concept of the processing so far is shown in FIG.

FIG. 3 is a diagram for explaining the procedure for generating the convex hull and the quadrangle S in the original texture image. FIG. 3 (a)
Indicates a vertex or a control point specified in the original texture image. In this way, the regions required as texture data in the original texture image are set by the vertices and control points. In (b), a state in which a convex hull figure is generated based on the points set in the original texture image is shown. The convex hull figure is a polygon formed by connecting some of the set vertices / control points, as shown in FIG.
It is a polygon that includes all vertices and control points and has the largest area.

When a convex hull figure is obtained as shown in FIG. 3B, the quadrangle S formed by the straight lines including any four sides of the convex hull figure having the smallest area is determined as the quadrangle S. ((C) of FIG. 3).

Using the quadrangle S generated as described above, texture data is generated in step S208 and the subsequent steps.

In step S208, a certain coordinate rectangle R is assumed, and a first coordinate conversion system for converting the rectangle S into the rectangle R is generated. FIG. 4 is a diagram for explaining the correspondence between the quadrangle S and the rectangle R. Further, FIG. 5 is a diagram for explaining the correspondence between points inside the quadrangle S and the rectangle R. In the first coordinate conversion system, as shown in FIG. 4, the vertices S and the vertices of the rectangle R are associated with each other, and as shown in FIG.
Bilinear interpolation is used to make the point (u, v) inside the quadrangle S correspond to the point (s, t) inside the rectangle R (where 0 ≦ s ≦ 1, 0 ≦ t ≦ 1). Then, the following equation u = (1-t). {(1-s) .x1 + s.x2} + t. {(1-s) .x4 + s.x3.s} v = (1-t). {(1- s) · y1 + s · y2} + t · {(1-s) · y4 + s · y3 · s}. Where (x1, y1), (x
2, y2), (x3, y3), (x4, y4) are the vertex coordinates of the quadrangle P1, P2, P3, P4, respectively. As described above, in the generation of the first coordinate conversion system, a conversion system in which (u, v) is obtained by substituting (s, t) is generated.

Similarly, in step S209, a second coordinate transformation system for transforming the rectangle R into the quadrangle S, which is the inverse transformation of the transformation, is generated. This is the above equation (s, t)
If it is regarded as a simultaneous equation of and is solved for (s, t), it becomes a conversion formula for obtaining the (s, t) value from the (u, v) value. The reason why such a second coordinate transformation system is necessary is
As shown in FIG. 3, where the vertices (control points) of the shape correspond to in the image is specified. If this image is transformed into a rectangle, what is that point? The reason is that you don't understand. That is, the designated point corresponding to the vertex at the designated time is the quadrangle S
It is on the top and is given by (u, v). If it is not determined where these designated points correspond on the rectangle R, the deformed image and the shape cannot be associated. Therefore, a conversion system for obtaining (s, t) on the rectangle R corresponding to the point (u, v) on the quadrangle S is required.

Next, in step S210, the rectangle R is regarded as an image of a certain resolution, and an area for storing the image data of this rectangle R is secured in the storage device 103. Then, the position P (s,
t) is converted by the first coordinate conversion system, and the position P ′ (u, v) on the original texture image is calculated. Here, the position P is not the value of the pixel position itself of the image of the rectangle R, but the normalized value in each of the vertical and horizontal directions, and (s, t)
It is represented by. Next, in step S211, the pixel of the texture original image closest to the position P ′ on the texture original image thus obtained is found, and the pixel value is stored as the pixel A in the image data in the storage device 301. The above steps S210 to S211 are performed on all pixels of the image of the rectangle R (step S21).
2). In this way, the image data of the rectangle R is obtained, and this is stored in the storage device 103 as image data.

Further, to which position on the rectangle R the designated point used for the region designation such as the vertices / control points designated in step S202 corresponds, that is, step S21.
The position on the image generated in 0 to S212 is calculated using the second coordinate conversion system (step S2).
13). The obtained pointing point is also stored in the storage device 103 as pointing point information data. Finally, step S
The images generated up to 212 and the position of the designated point calculated in step S213 on the image are output as texture data. By this, image data for texture,
Both the information such as vertices and control points on the side where the texture is pasted (patch etc.) can be acquired.

6 and 7 show examples of results obtained by applying the present embodiment. FIG. 6 is a diagram in which an area required in step S202 is specified in the texture original image read in step S201. The points indicated by crosses correspond to the vertices of the patch. Based on this, steps S203 to S21
The process up to 4 is performed and the output result is shown in FIG. Image data that cuts out only the required area, and
The data of the designated point is thus obtained. Note that FIG.
FIG. 7 is a color grayscale image.

FIG. 6 is a photograph of the entrance of the house, where the floor surrounded by the crosses has a net-like pattern unwound. In FIG. 6, since the floor portion that is the target of this texture data is photographed from an obliquely upper direction,
The pattern seems to shrink as it goes up in the drawing. If such a texture image is cut out using a conventional rectangular area, a high resolution is required to reproduce the finer pattern in the upper part, resulting in an increase in the amount of texture data. Alternatively, when the resolution is limited, the image partially deteriorates.

On the other hand, in the present embodiment, the data is converted into a rectangle as shown in FIG. 7, a substantially uniform pattern (close to the actual pattern) is reproduced, and this is used as texture data, so it is unnecessary. It is not necessary to have a high resolution, and the amount of texture data can be reduced. Further, since the texture data is generated so as to include the necessary area as large as possible, useless data included in the texture data can be reduced and the data amount of the texture data can be reduced. The aspect ratio of the rectangle in FIG. 7 is preferably set according to the three-dimensional shape. For example, in order to restore the contracted pattern in the upper portion of FIG. 6, it is preferable that the aspect ratio of the rectangle R in FIG. 7 matches the aspect ratio of the actual entrance floor.

As described above, according to the present embodiment, in shooting an object used as a texture, the size of the object and the degree of freedom in the shooting direction are increased, so that the shooting of the original texture image is simplified. In addition, when extracting a necessary area from the original texture image, useless areas are effectively excluded, so that the data capacity of the texture data can be reduced.

Further, even if the image to be used as a texture is partially fine as shown in FIG. 6 due to the influence of the photographing direction, the resolution is not increased unnecessarily, Moreover, the texture data can be generated without causing deterioration of the image.

The object of the present invention achieved by the function of the above apparatus or the function of the method can also be achieved by the storage medium in which the program of the above-mentioned embodiment is stored. That is,
This is because the storage medium is mounted on the device and the program itself read from the storage medium achieves the novel function of the present invention. In this case, in the configuration of FIG. 1, for example, the storage device 103 can be configured by a floppy disk and the program can be supplied from the floppy disk. The program supplied from the floppy disk is R
It is loaded into the AM 102b and executed by the CPU 101. The structural characteristics of the program according to the present invention for this purpose are as shown in FIG.

FIG. 8A is a diagram showing a procedure of control execution by a program. Reference numeral 80 denotes a reading process, which reads an original image that is the basis of the texture through the input / output interface and stores it in the storage device 103 (step S201 in FIG. 2). Reference numeral 81 is a designation process, which designates a necessary area on the texture original image which is the basis of the texture, by the vertices or control points of the patch of the pasting destination (step S202). Reference numeral 82 denotes a generation process, which generates a quadrangle surrounding the area designated in the designation process 81 based on a predetermined rule, and extracts a quadrangle having the smallest area from the generated quadrilaterals (steps S203 to S207). .

Reference numeral 83 denotes a first conversion process, which is a generation process 82.
The image surrounded by the quadrangle extracted in step S4 is converted into a rectangular image of a desired size (step S208 to step S2).
12). Further, 84 is a second conversion process, which converts the specified area (feature point) specified in the previous specification processing 81 into an area on the rectangular image (step S213).
Then, 85 is an output process, which outputs the rectangular image obtained by the first conversion process 83 and the information indicating the designated area obtained by the second conversion process 84 as texture data (step S214).

FIG. 8B is a memory map showing the storage state of the program module for executing each of the above processes in the storage medium. Read processing module 80 ',
Designation processing module 81 ', generation processing module 8
2 ′, the first conversion processing module 83 ′, the second conversion processing module 84 ′, and the output processing module 85 ′ respectively include a reading processing 80, a designation processing 81, a generation processing 82, and a first processing.
It is a program module for executing the conversion process 83, the second conversion process 84, and the output process 85.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus. In this case, the storage medium storing the program according to the present invention constitutes the present invention. Then, by reading the program from the storage medium to the system or device, the system or device operates in a predetermined manner.

[0039]

As described above, according to the present invention,
It is possible to simplify the shooting when preparing the texture original image and eliminate waste (reduce unnecessary areas) when extracting a necessary area from the texture original image.

[0040]

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a computer device according to the present embodiment.

FIG. 2 is a flowchart showing a procedure of texture data generation processing according to the present embodiment.

FIG. 3 is a diagram illustrating a procedure for generating a convex hull and a quadrangle S in a texture original image.

FIG. 4 is a diagram illustrating a correspondence between a quadrangle S and a rectangle R.

FIG. 5 is a diagram illustrating correspondence between points inside a rectangle S and a rectangle R;

FIG. 6 is a diagram showing an example of a texture original image and a state in which an area is designated.

7 is a diagram showing texture data obtained from the original texture image of FIG.

FIG. 8 is a diagram illustrating a configuration of a storage medium that stores a control program for realizing the control of the present embodiment.

[Explanation of symbols]

 101 CPU 102 Storage Device 2 103 Storage Device 1 104 Input / Output Interface 105 Keyboard 106 Mouse 107 Display Device

Claims (7)

[Claims] 1. A texture data generation device for generating texture data used for computer graphics, comprising: a designating unit for designating a required area on a texture original image which is a basis of a texture; and a designating unit designated by the designating unit. Generating means for generating a quadrangle surrounding the region based on a predetermined rule and extracting the quadrangle having the smallest area; and converting the image enclosed by the quadrangle extracted by the generating means into a rectangular image of a desired size. A first conversion means, a second conversion means for converting the designated area designated by the designation means into an area on the rectangular image, and the rectangular image obtained by the first transformation means and the second conversion means. An output unit that outputs the obtained information indicating the specified area as texture data. 2. The designating unit designates a required area by designating a plurality of feature points representing a shape of an image to be pasted on a texture image, and the second converting unit designates the designating region. The texture data generation device according to claim 1, wherein the plurality of feature points designated by the means are converted into feature points at corresponding positions on the rectangular image. 3. The generating means forms a convex hull polygon surrounding the plurality of feature points, and a quadrangle having the smallest area among quadrangles formed by straight lines including four sides of the convex hull polygon. The texture data generation device according to claim 2, wherein 4. A texture data generation method for generating texture data used for computer graphics, comprising: a designating step of designating a required area on a texture original image which is a basis of texture; and a designating step designated by the designating step. Generating a quadrangle surrounding the region based on a predetermined rule and extracting the quadrangle having the smallest area; and converting the image enclosed by the quadrangle extracted in the generating step into a rectangular image of a desired size. A first conversion step, a second conversion step of converting the specified area specified in the specification step into an area on the rectangular image, and the rectangular image obtained in the first conversion step and the second conversion step. An output step of outputting the obtained information indicating the designated area as texture data. 5. The designating step designates a required area by designating a plurality of feature points representing the shape of an image to be pasted on the texture image, and the second converting step comprises designating the designated area. The texture data generation method according to claim 4, wherein the plurality of feature points designated in the step are converted into feature points at corresponding positions on the rectangular image. 6. The generating step forms a convex hull polygon surrounding the plurality of feature points, and a quadrangle having the smallest area among quadrangles formed by straight lines including four sides of the convex hull polygon. The texture data generating method according to claim 5, wherein the texture data is extracted. 7. A computer control device for controlling a computer by reading a predetermined program from a memory medium, wherein the memory medium designates a necessary area on a texture original image which is a basis of a texture. The procedure code of the process, the procedure code of the generation process of generating a quadrangle surrounding the area designated in the designation process based on a predetermined rule, and extracting the quadrangle having the smallest area, and the procedure code of the generation process. Procedure code of a first conversion step for converting an image surrounded by a rectangle into a rectangular image of a desired size, and a procedure of a second conversion step for converting a designated area designated in the designation step into an area on the rectangular image An output process that outputs, as texture data, a code, a rectangular image obtained in the first conversion step, and information indicating the designated area obtained in the second conversion step. Computer controller, characterized in that it comprises a procedure code.