JPH02148273A - Method for two-dimensionally expressing three-dimensional object - Google Patents

Abstract

PURPOSE:To easily two-dimensionally express a three-dimensional object having surface information by repeatedly allocating a desired unit pattern to a desired object area of the surface of the three-dimensional object in a three-dimensional coordinate system and two-dimensionally projecting it. CONSTITUTION:A CAD device 1, a format converter 2, an operation processing device 3, a color scanner 4, a surface information storage device 5, and a graphic display device 6 are provided. The three-dimensional object is designed on the three-dimensional coordinate system to obtain shape data of the three- dimensional object, and it is displayed with wire frames on a two-dimensional plane, and a partial area of the surface is designated as the object area, and the unit pattern taken in by the scanner 4 is repeatedly allocated to the designated object area to obtain three-dimensional shape data of the three-dimensional object having surface information, and a two-dimensional picture is obtained by two-dimensional projection. Thus, the three-dimensional object having surface information is efficiently displayed two-dimensionally.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a two-dimensional representation method of a three-dimensional object, and particularly to a two-dimensional representation method of a three-dimensional object using image processing by a computer.

[Conventional technology]

In architecture and interior design, it is necessary to draw exterior and interior drawings and present them to customers. Such drawings include
Various three-dimensional objects such as doors, windows, and furniture will be drawn, and these three-dimensional objects have surface information such as wood grain patterns, fabrics, and metal surfaces. In the past, the creation of such drawings had to be done manually by a designer, but in recent years, methods using computer systems using CAD have been attempted.

[Problem to be solved by the invention]

However, the manual method by the designer requires a lot of effort and time, and has the problem of poor work efficiency. In addition, with the currently known methods using CAD, efficient methods are being realized for designing three-dimensional shapes, but methods for forming two-dimensional images of three-dimensional objects with surface information are not efficient. The situation is that no good method has been proposed. In particular, there is no known efficient method for producing two-dimensional displays that give a sense of simplicity, such as wood grain patterns, cloth, and metal surfaces.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method that can efficiently display a three-dimensional object having surface information in two dimensions.

[Means to solve the problem]

The present invention provides a method for expressing a three-dimensional object with surface information on a two-dimensional plane, which includes the steps of designing a three-dimensional object on a three-dimensional coordinate system and obtaining shape data of the three-dimensional object; A stage of displaying a wire frame of a three-dimensional object on a two-dimensional plane based on the shape data, a stage of inputting a unit pattern that can be repeatedly arranged on a two-dimensional plane, and a stage of displaying a three-dimensional object on a two-dimensional plane based on the wire frame display. A step of specifying a part of the surface of the original object as a target area, and repeating the assignment of a unit pattern to the specified target area on a 3D coordinate system to generate 3D shape data of the 3D object with surface information. and a step of two-dimensionally projecting the three-dimensional shape data obtained in the previous step to obtain a two-dimensional image.

In addition, after the unit pattern allocation, a waveform correction line is defined along the boundary line of each unit pattern, and data is corrected so that a continuous pattern can be obtained within the closed area surrounded by this waveform correction line. This is how it was done.

Furthermore, for each pixel on the waveform correction line, the pixel value of each pixel is corrected based on the pixel values of surrounding pixels.

[For production]

In the method according to the present invention, a desired pattern is allocated to a desired target area on the surface of a three-dimensional object on a three-dimensional coordinate system.

Since the layout is done on a three-dimensional coordinate system, the prepared pattern can be laid out exactly as it is. Further, since the pattern may be any information as long as it is a two-dimensional image, any pattern inputted by a color scanner or the like can be used. Furthermore, since the patterns can be repeatedly arranged on a two-dimensional plane, even if the target area is wider than the prepared pattern, it is possible to repeatedly allocate the prepared pattern. A two-dimensional image can be easily obtained by two-dimensionally projecting a three-dimensional object to which a pattern has been allocated in this manner. In addition, by correcting data using waveform correction lines, it is possible to make discontinuities in patterns that may occur between unit patterns less noticeable, and for pixels on waveform correction lines, the pixel value is calculated based on the surrounding pixels. If you correct
Discontinuities can be made less noticeable.

〔Example〕

The present invention will be described below based on illustrated embodiments. 1st
The figure is a flowchart of a method according to an embodiment of the present invention, and the second
The figure is a block diagram showing the configuration of an apparatus for carrying out the procedures in this flowchart. First, the block diagram shown in FIG. 2 will be explained. The CAD device 1 is a device capable of designing a general three-dimensional shape, and a desired three-dimensional shape is defined in a three-dimensional coordinate system by this device. The three-dimensional shape data defined here is given to the arithmetic processing device 3 via the format conversion device 2. This arithmetic processing device 3 is specifically constituted by a processing system within a host computer. The format conversion device 2 has a function of converting three-dimensional shape data created in the data format in the CAD device 1 to the data format in the arithmetic processing device 3.

On the other hand, the color scanner 4 functions to input surface information to be assigned to the object surface. For example, when a wood grain pattern is captured by this color scanner 4, the data of the captured wood grain pattern is transferred to the arithmetic processing unit 3 as two-dimensional image data.
sent to. This wood grain pattern data can be stored in the surface information storage device 5 and read out by the arithmetic processing device 3 whenever necessary. In the present invention,
As will be described in detail later, the color scanner 4 receives a pattern that can be repeatedly arranged. The arithmetic processing unit 3 has the function of executing various processes to be described later, displays the processing progress on a graphic display 6 to provide necessary information to the operator, and inputs instructions from the operator from the peripheral input device 7. do. As the peripheral input device 7, a tablet, a function key, a dial input device, or the like is used. The two-dimensional image finally obtained by the arithmetic processing unit 3 is outputted by a color hard copy device 8, and a hard copy is obtained.

Next, the processing according to the present invention will be explained with reference to the flowchart of FIG. First, in step S1, the shape of the three-dimensional object is designed. This is a work performed by the CAD device 1, and a three-dimensional object is defined on a three-dimensional coordinate system. Specifically, shape data is generated as a set of coordinate values in a two-dimensional coordinate system. For example, if the cube is as shown in Figure 3, 1. Part 8
Shape data is data indicating the relationship between the set of three-dimensional coordinate values of one vertex and these eight vertices. The method for generating this shape data is well known as a general CAD technique, so its explanation will be omitted here.

Next, in step S2, format conversion of the generated shape data is performed. This is because the CAD device 1 and the arithmetic processing device 2 generally have different data formats. This process is not necessary if the data format is common. The format-converted shape data is taken into the arithmetic processing unit 3.

Subsequent steps S3 and subsequent steps are processed by the arithmetic processing unit 3. First, in step S3, a wire frame display is performed based on the given shape data. This display is made on the graphic display 6.

FIG. 4 is a diagram showing an example of a display screen of the graphic display 6. As shown in FIG.

Here, the display screen is divided into an object display area 61, a surface information display area 62, and a command display area 63. The object display area 61 displays a two-dimensional projected image of a three-dimensional object to be processed, the surface information display area 62 displays a two-dimensional image to be assigned to the object surface, and the command display area 63 displays a two-dimensional projected image of a three-dimensional object to be processed. The various commands needed to do this will be displayed.

Let us now continue the explanation assuming that a cubic shape as shown in FIG. 3 is generated in step S1. A wire frame display is obtained by determining a viewpoint on a three-dimensional coordinate system and two-dimensionally projecting a three-dimensional object from this viewpoint position. Therefore, the wire frame display for the cubic shape as shown in FIG.
)become that way. If the operator does not like this display, he can obtain a different display by changing the viewpoint position using commands in the command display area 63. Note that various methods are known for projecting an object in a three-dimensional coordinate system onto a two-dimensional coordinate system based on a predetermined viewpoint position.

Once the wire frame is displayed, hidden line removal processing is performed in step S4. That is, the image shown in FIG. 4(b) is obtained from the image shown in FIG. 4(a). Since various methods for eliminating hidden lines are known, their explanation will be omitted here.

Next, in step S5, whether to allocate a pattern or not,
Decide whether to perform coloring treatment. The operator will specify one of them by inputting a command. After specifying the pattern layout, a pattern is selected in step S6. This selection may be made by displaying several patterns in the surface information display area 62, as shown in FIG. 4(C). The picture displayed here is based on image information input by the color scanner 4 and stored in the surface information storage device 5. The operator selects a desired pattern, such as a wood grain pattern or a polka dot pattern, from among the displayed patterns. This selection is easy to operate if the desired pattern is specified using the cursor C1 within the surface information display area 62, as shown in FIG. 4(d).

Next, in step S7, a layout plane is specified. This specifies which surface of the object the pattern is to be allocated to. Since the object is already displayed as a wire frame on the display screen, it is only necessary to designate the closed area surrounded by the wire as the layout plane. Specifically, as shown in FIG. 4Cd), the object display area 61
A cursor C2 is displayed within the screen, and by moving the cursor C2, a desired layout surface can be specified. Same ff1(d)
In the example, layout plane 81 is designated by cursor C2.

After a picture is selected in step S6 and a layout surface is specified in step S7, layout processing is performed in step s8. However, this allocation is performed on a three-dimensional coordinate system as follows. First, as shown in FIG. 5(a), a layout plane s1 is extracted on a three-dimensional coordinate system, and a plurality of pixels are defined on this layout plane S1. Each pixel has a three-dimensional coordinate value indicating its position. For example, in Figure 5 (a
) also has the coordinates (x, y, z) p
p p one. Note that in the figure, for convenience of explanation, one pixel is shown as a large closed area, but in reality, one pixel is a small area that is recognized as a point.

On the other hand, as shown in FIG. 5(b), the pattern E to be allocated
is originally formed as a set of pixels (R), and each pixel has a two-dimensional coordinate value. For example, pixel Q is (
It has coordinate values (x, y). If the pixels on the layout surface Sl and the pixels on the pattern E are arranged at the same pitch, a one-to-one correspondence will be established between the two pixels. For example, Fig. 5(a)
The pixel P in the figure corresponds to the pixel Q in FIG. This correspondence relationship can be determined by calculation from the coordinate values of each pixel.

Incidentally, each pixel Q constituting the picture E should be given some color value. Therefore, the color value of any pixel P on the layout surface Sl can be determined based on the color value given to the corresponding pixel Q on the pattern E. If necessary, the final color value can also be determined by assuming a light source in a three-dimensional coordinate system and taking into account the position of this light source and the color of the light source. Such a method for determining color values is described in, for example, Japanese Patent Application Laid-Open No. 1988-1.0774.

When such color value determination is performed for all pixels on the layout surface S1, the layout process is completed. When the layout process is completed, a set of pixels on a three-dimensional coordinate system having each color value is two-dimensionally projected and displayed on the graphic display 6, thereby obtaining an image as shown in FIG. 4(e). The above pattern assignment can be performed not only on flat surfaces but also on curved surfaces. For specific methods, please refer to the above publication.

The basic principle of the pattern allocation process performed in step S8 has been described above, but in the present invention, a repeating pattern is actually used as a pattern, and this pattern is repeatedly allocated. A method for performing this repeated allocation will be explained with reference to FIG. First, let's start with Part 6.
A printing material 9 made of an arbitrary material as shown in FIG. 9(a) is prepared.

Marks M (so-called register marks) for limiting the area as shown in FIG. 6(b) are then written on this printing material 9. Here, the area limited by this mark M (the part surrounded by the broken line in the figure) is made to constitute one pattern that can be repeatedly arranged. In other words, when the same pattern is arranged vertically and horizontally on a two-dimensional plane, the pattern is made to appear continuous and natural at each boundary. For example, the pattern on the right side and the pattern on the left side of the part surrounded by the broken line in FIG. 6(b) match, and the pattern on the top side and the pattern on the bottom side match. If the printed matter originally has a repeating pattern, an area corresponding to one pitch of this pattern may be designated by the mark M. If a discrepancy occurs, the pattern at the border is corrected to create a continuous pattern. Subsequently, as shown in FIG. 6(C), this print 9 is photographed with a camera 10.

The film 11 obtained as a result is pasted on the drum 41 of the color scanner 4, as shown in FIG. 6(d)i.
input into the scanner. At this time, the area surrounded by the mark M is the input target. In this way, unit patterns as shown in FIG. 6(e) are stored in the surface information storage device 5. Note that if information on the actual size of the unit pattern is also input when inputting with the scanner, the layout can sometimes be done based on the principle.

FIG. 6(r) shows the principle of repeated allocation. Now, the layout surface S1 is designed as a square with actual size information of length a on one side, and the unit pattern shown in FIG.
It is assumed that the square is input as a square with actual size information of side length b (b<a).

In this case, the allocation surface s1 is divided into squares with side length b using the reference point O as a reference, and each divided square is divided into
) The work of assigning the +1 symbols shown in ) will be repeated. By adopting this method of repeatedly allocating unit patterns, the amount of information of the pattern can be reduced, and the memory capacity required for image processing can be kept small.

By the way, when unit pictures are repeatedly allocated, discontinuity may occur between the unit pictures. For example, in the example shown in FIG. 7, the unit patterns U1 and U2 are misaligned and are discontinuous.

Such discontinuity is due to the scanner input accuracy when pasting the pattern onto the drum 41 of the scanner 4 and inputting it. In order to deal with such discontinuities, the following processing may be performed. First, as shown in Figure 8(a),
A waveform correction line f1 having a sinusoidal waveform that vibrates vertically around the upper side H1 of one unit picture is defined. continue,
A waveform correction line f2 having the same amplitude and phase as this fl,
It is defined at a position that vibrates around the horizontal line g near the lower side H2 of the unit pattern. Note that the position of the horizontal line g is determined so that the lowest point of the waveform correction line f2 is exactly on the lower side H2. Then, the image of the lower half period of the waveform correction line f1 (the area indicated by dots in the figure) is replaced with the image of the lower half cycle of the waveform correction line f2 (the area indicated by diagonal lines in the figure). That's what I do. This completes the processing on the upper side. Similar processing is performed for the bottom, right, and left sides. This situation is shown in FIG. Here, (a) in the same figure is an original image, and (b) in the same figure is a corrected image after processing.

The upper side areas A' and B' shown in FIG.
It has been replaced by images of areas A and B near the lower side shown in FIG. This is because the processing explained in FIG. 8 was performed. Similarly, the lower side region C' shown in FIG.
) is replaced by the upper side neighborhood region C shown in (b) of the same figure.
The right side area D′ shown in FIG.
The left side area E shown in FIG.
', F' are the right side neighborhood area E shown in FIG.
Replaced by F. Note that areas A' and E' in Figure (b) are partially overlapping areas (indicated by hatching).
However, such an area may be replaced by a composite image of area A and area E. For example, it may be replaced with a pixel whose pixel value is the average value of the pixel value of area A and the pixel value of area E.

When correction is performed using the waveform correction line as described above, discontinuities occurring between unit patterns become less noticeable. This situation is the first
This is shown in the example in Figure 0. Figure 10(a) is before correction, and Figure 10(b) is
) indicates the corrected pattern. In the case of a pattern with vertical stripes as in this example, as shown in Figure (a), before correction there is discontinuity in the pattern at the top side H] and bottom side H2, and the stepped portion due to the discontinuity is along sides H1 and H2. Because they are lined up horizontally, they are very noticeable. However, when correction is performed using a waveform correction line, the step portion due to discontinuity becomes distributed on the sine wave, as shown in Figure (b).
It becomes less noticeable.

FIG. 11 shows the results of similar corrections made to a picture with a diagonal pattern. li as shown in figure (a)
In the case of a unit pattern, a positional shift occurs in the pattern between the upper side H1 and the lower side H2, so a level difference occurs at the boundary of the unit pattern. Therefore, as shown in FIG. 3(b), the waveform correction line f1.
．． When f2 is defined and the image area near the upper side H1 is replaced, a pattern as shown in FIG. 2C is obtained. Upper side H
An enlarged view of the area around 1 is shown in Fig. 1(d). Before correction, upper side H1
The steps were lined up in a straight line along the same line, but after the correction, the connection between the steps in the pattern becomes wavy, making it less noticeable.

After performing the correction processing as described above, if the following processing is further performed, the difference in level can be made more inconspicuous. First, a pixel on the waveform correction line fl is extracted, and the pixel value of this pixel is corrected based on the pixel values of surrounding pixels. Specifically, the following processing is performed. now,
In FIG. 12, it is assumed that the pixel value of one pixel on the waveform correction line f1 is p5. In this case, the pixel values p1 to p9 of the pixel including that pixel and its surrounding pixels
The average value of is used as the new pixel value of that pixel. Therefore, in the case of the example shown in FIG. 12, the new pixel value of the pixel with the pixel value p5 in the center is as follows. Such processing is performed for all pixels on the waveform correction line f]. This smoothing process alleviates fluctuations in pixel values at the step portion, making it possible to make the step less noticeable. If pixel values are smoothed for each color component, variations in color will also be alleviated, and not only steps in the shape of the picture but also steps in color can be eliminated.

In the above-described embodiment, a sinusoidal waveform line was used as the waveform correction line, but the present invention is not limited to correction using such a sinusoidal waveform, and any waveform shape may be used. be able to.

In short, any correction line may be used as long as the steps can be avoided from being lined up on a straight line.

On the other hand, if coloring processing is specified in step S5, color selection is performed in step S9. This is, for example, R
All you have to do is input the color values of each of the three primary colors of GB from the keyboard. Subsequently, a colored surface is specified in step SIO. This can be done by specifying the colored surface S3 with the cursor C3 as shown in FIG. 4<n. In the subsequent coloring process of step Sll, a specified color is applied to the specified colored surface. That is, each pixel constituting the colored surface S3 is given a color value corresponding to the designated color, and by displaying the two-dimensional projected image again, an image as shown in FIG. 4(g) is obtained.

As described above, the pattern assignment process or coloring process is repeatedly performed for each side (step 512). When all the processes are completed, a two-dimensional image is output in step 913. That is, a two-dimensional projected image is output by the color hard copy device 8,
This hard copy will be presented to the customer. In addition,
If the data of each pixel in the three-dimensional coordinate system is stored, by reading this data, it is possible to easily respond to changes in layout patterns, color changes, etc. according to customer requests.

〔Effect of the invention〕

As described above, in the method according to the present invention, a desired unit pattern is repeatedly allocated to a desired target area on a three-dimensional object surface on a three-dimensional coordinate system, and this is two-dimensionally projected. It becomes possible to easily perform two-dimensional representation of the original object. Furthermore, data correction using a waveform correction line and pixel direct correction on the waveform correction line can make discontinuities in patterns that occur between unit patterns less noticeable.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the steps of an embodiment of the two-dimensional representation method for a three-dimensional object according to the present invention, FIG. 2 is a block diagram of a system suitable for carrying out the steps in FIG. 1, and FIG. is CA
A diagram showing an example of a three-dimensional object designed by the D device,
FIG. 4 is a diagram showing an example of a display screen by the device shown in FIG. 2, FIG. 5 is a diagram explaining the principle of the allocation process in step S8 of FIG. 1, and FIG. 6 is a method of repeated allocation according to the present invention. FIG. 7 is an explanatory diagram of discontinuity occurring between unit patterns, FIGS. 8 and 9 are principle diagrams of data modification using waveform modification lines according to the method of the present invention, and FIGS. FIG. 11 is a diagram showing the results of data modification using a waveform modification line, and FIG. 12 is a diagram showing the principle of pixel value modification for pixels on the waveform modification line. 9... Material printing, 10... Camera, 11... Film, 41... Drum, 61... Object display area,
62...-Surface information display area, 63... Command display area, 01-C3... Cursor, P, Q... Pixel,
Ul, U2...Unit pattern, fl, f2...Waveform correction line. Applicant's agent Hiroshi Shimura Ward 1 (α) (b) Coffin Figure 5 Figure 4 Figure 9 Ward

Claims (3)

[Claims] (1) A method for expressing a three-dimensional object with surface information on a two-dimensional plane, which includes the steps of designing a three-dimensional object on a three-dimensional coordinate system and obtaining shape data of this three-dimensional object; a step of displaying the three-dimensional object in a wire frame on a two-dimensional plane based on the shape data; a step of inputting a unit pattern that can be repeatedly arranged on the two-dimensional plane; and based on the wire frame display. designating a part of the surface of the three-dimensional object as a target area, and repeatedly assigning the unit pattern to the target area on the three-dimensional coordinate system to create a three-dimensional image of the three-dimensional object having surface information. A two-dimensional representation method for a three-dimensional object, comprising: a step of obtaining original shape data; and a step of two-dimensionally projecting the three-dimensional shape data obtained in the previous step to obtain a two-dimensional image. (2) A method for expressing a three-dimensional object with surface information on a two-dimensional plane, comprising the steps of designing a three-dimensional object on a three-dimensional coordinate system and obtaining shape data of the three-dimensional object; a step of displaying the three-dimensional object in a wire frame on a two-dimensional plane based on the shape data; a step of inputting a unit pattern that can be repeatedly arranged on the two-dimensional plane; and based on the wire frame display. designating a part of the surface of the three-dimensional object as a target area, and repeatedly assigning the unit pattern to the target area on the three-dimensional coordinate system to create a three-dimensional image of the three-dimensional object having surface information. At the stage of obtaining the original shape data, a waveform correction line is defined along the boundary line of each unit pattern allocated in the previous step, so that a continuous pattern can be obtained within the closed area surrounded by this waveform correction line. , a step of correcting the data obtained in the previous step, and a step of projecting the three-dimensional shape data corrected in the previous step in two dimensions to obtain a two-dimensional image. expression methed. (3) A method for representing a three-dimensional object with surface information on a two-dimensional plane, which includes the steps of designing a three-dimensional object on a three-dimensional coordinate system and obtaining shape data of this three-dimensional object; displaying the three-dimensional object as a wire frame on a two-dimensional plane based on the shape data; inputting a unit pattern that can be repeatedly arranged on the two-dimensional plane as a set of a plurality of pixels; a step of specifying a part of the surface of the three-dimensional object as a target area based on the wire frame display; and repeatedly allocating the unit pattern to the target area on the three-dimensional coordinate system, A step to obtain three-dimensional shape data of a three-dimensional object with surface information consisting of a set, and a waveform correction line is defined along the boundary line of each unit pattern allocated in the previous step, and the area surrounded by this waveform correction line is In order to obtain a continuous pattern within the closed area, the data obtained in the previous step is corrected, and for each pixel on the waveform correction line, the pixel value of each pixel is compared to the pixel value of the surrounding pixels. There is a step of correcting based on the values, and a two-dimensional projection of the three-dimensional shape data corrected in the previous step.
A method for representing a three-dimensional object in two dimensions, comprising the steps of obtaining a two-dimensional image.