JP2003030676A - Three-dimensional image plotting method and device and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional image plotting method and a device therefor and a recording medium relying on inverse perspective drawing for general object plotting including reflection, refraction and transmission and for various inverse perspective plotting, and to provide the three-dimensional image plotting method and the device therefor and the recording medium for forming various images in which perspective and view points are freely set including the inverse perspective. SOLUTION: A line-of-sight direction to project an object, a screen to project the object and a divergence point are set. In the case that the divergence point is set on the far side of the screen seen from the line-of-sight direction, the divergence point is defined as an inverse view point viewable from many view points and the object is projected and plotted to a pixel with a straight line connecting the pixel and the divergence point as the line of sight for each pixel of the screen. In the case that the divergence point is set on the front side of the screen, the divergence point is defined as the view point and the object is projected and plotted on the screen by the perspective. Further, in the case that the divergence point is set practically at the infinitely front part or infinitely rear part of the screen seen from the line-of-sight direction, the object is projected and plotted on the screen by a parallel projection method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer-based image drawing method, and more particularly to a three-dimensional image drawing method and apparatus for projecting and drawing an object in a three-dimensional space, and a recording medium.

[0002]

2. Description of the Related Art Computer-based three-dimensional images (three-dimensional images)
CG) drawing is first researched and developed with the aim of improving realism. For example, in the movie industry such as Hollywood, 3D
Work production has been done with the realism of CG in the foreground. This conventional general three-dimensional CG projection method is a general method for simulating a light phenomenon (reflection, refraction, transmission). Based on the perspective projection method that calculates the brightness, the fisheye lens and panoramic effect were used in part. The parallel projection method in which the object is directly projected in parallel corresponds to a special case of the perspective projection method in which the viewpoint is set to infinite rear.

This general projection method has features such as fixed line of sight, monocular vision, and uniform resolution on the entire screen.
It does not capture all aspects of the three-dimensionality that humans feel. Therefore, for the purpose of providing a more natural and effective three-dimensional image, for example, a technique of setting a larger value of transparency as the distance from the viewpoint is smaller (Japanese Patent Laid-Open No. 2000-149062 and its apparatus). ), A technique for performing blurring processing in proportion to the distance from a surface set to be in focus (Japanese Patent Laid-Open No. 08-063614, texture mapping method), etc. It is an improved technology based on the simple perspective projection method.

On the other hand, in recent years, a genre called non-photorealistic CG has been recognized. For example, it is a technique for generating a picture such as a cel animation or a picture handwritten with a pen or a brush. Other,
As is often done in painting, three-dimensional CG has also been studied, which emphasizes the part that the author is paying attention to by drawing it too large. Even in recent movies, it has become a hot topic to create images that cannot be obtained with ordinary cameras using live-action images, image processing, and CG. Similar to the change from the time when realism was valued in paintings to the time when people enjoy free expression, similar movements are about to occur in 3D CG. Therefore, as is done in painting, for example, techniques such as the reverse perspective projection and various projection methods, and the mixing of images from multiple viewpoints are indispensable for 3D CG. .

Among the paintings that have been drawn by various painters since ancient times, there are some paintings that use the reverse perspective. Regardless of whether the creator was consciously drawing in that way or not, such a drawing method is vaguely called reverse perspective, but a method for drawing in reverse perspective was defined. It does not mean that

As a technique for realizing a projection method using inverse perspective in three-dimensional CG, a special inverse perspective projection method (M. Inakage, Non- linear perspective projectio
n, Modeling in Computer Graphics, Springer-Verla
g, pp.203-215, 1991), but it is applicable only to an object having a perfect diffuse reflection surface because only the definition related to morphology is made. Since there is only one degree, it is not possible to perform various kinds of inverse perspective drawing, and because perspective projection and inverse perspective projection are not integrally related, it is not possible to generate various images with perspective and viewpoints set freely. However, in fact, it has not been used for general 3D CG software.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and is capable of drawing a general object involving reflection, refraction, and transmission and capable of various reverse perspective drawing. A first object of the present invention is to provide a three-dimensional image drawing method and apparatus and a recording medium by the projection method, and further,
A second object of the present invention is to provide a three-dimensional image drawing method and apparatus and a recording medium capable of generating various images including the perspective method and the perspective as desired, and the recording medium.

[0008]

In order to achieve the above first object, a three-dimensional image drawing method of the present invention is a three-dimensional image drawing method by a computer for projecting and drawing an object in a three-dimensional space on a screen. A divergence point is set on the line-of-sight direction on which the object is projected, on the screen on which the object is projected, and on the other side (front side) of the screen viewed from the line-of-sight direction. The divergence point connects the pixel and the divergence point for each pixel of the screen. This is a three-dimensional image drawing method by the inverse perspective projection method, which is an inverse viewpoint seen from multiple viewpoints, in which an object is projected and drawn on a pixel with a straight line as the line of sight.

In order to achieve the above-mentioned second object, the three-dimensional image drawing method of the present invention is a three-dimensional image drawing method by a computer for projecting and drawing an object in a three-dimensional space on a screen. , The screen for projecting the object, and the divergence point are set, and when the divergence point is set on the other side (front) of the screen as seen from the line-of-sight direction, the divergence point is set as the reverse viewpoint and the object is projected by the inverse perspective projection method described above. When the divergence point is set on the front side (rear side) of the screen as viewed from the line of sight, the divergence point is set as the viewpoint and the object is projected and drawn on the screen by the perspective projection method. It was done.

Further, in the case where the divergence point is set substantially infinitely forward or infinitely rearward of the screen as viewed from the line-of-sight direction, the third order for projecting and drawing the object on the screen by the parallel projection method. This is the original image drawing method.

Furthermore, a step of setting a main viewpoint and a main screen for gathering a plurality of objects drawn by mixed projection methods into one image, and a tentative line-of-sight direction for temporary drawing for each object From the step of setting the screen and the tentative divergence point, and the relationship between the set tentative line-of-sight direction and the tentative screen and the tentative divergence point for each object, the inverse perspective projection method, the perspective projection method, or the parallel projection method. Of any one of the following, and the step of projecting and drawing the object on the temporary screen by the determined projection method, and the step of projecting and drawing the temporarily drawn temporary screen from the main viewpoint to the main screen. This is a three-dimensional image drawing method in which a projected and drawn image is a three-dimensional image.

An apparatus of the present invention is a three-dimensional image drawing apparatus for drawing a three-dimensional image using the three-dimensional image drawing method of the present invention, and a recording medium of the present invention is a three-dimensional image drawing of the present invention. It is a computer-readable recording medium in which a three-dimensional image drawing program for realizing a function of drawing a three-dimensional image using the method is recorded.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The object in the present invention is a unit of a projection area to be projected under a specific projection method and projection condition, and does not necessarily mean a physical object.
The shape of the projection area containing multiple physical objects, or
A form in which one physical object is divided into a plurality of projection areas is also possible.

The three-dimensional image drawing method of the present invention is a projection drawing method using a so-called ray tracing method. Generally, an object is composed of elements of color, shape and material, and the material is completely diffused and reflected. Except for special objects such as
You cannot draw unless the viewpoint is determined. In the three-dimensional image drawing method by the inverse perspective projection method of the present invention, when a scene in which a certain point is viewed from a large number of viewpoints is projected on a screen, an image drawn by a kind of the reverse perspective method is displayed on the screen. It was discovered and made.

Generally speaking, a viewpoint can see the range of the screen, but each viewpoint of the multiple viewpoints in the present invention is
As shown in the conceptual diagram for explaining the principle of the reverse perspective projection method according to the present invention in FIG. 1, the line of sight is a straight line connecting each pixel and the reverse viewpoint, and there are as many viewpoints as there are pixels. Become. That is, the three-dimensional image obtained by the reverse perspective projection method of the present invention has a line-of-sight direction in which an object is projected (a direction from left to right in FIG. 1), a screen on which the object is projected, and the other side of the screen viewed from the line-of-sight direction. Then, a divergence point is set, and for each pixel of the screen, an object is projected on the pixel with the line connecting the pixel and the divergence point as the line of sight.
Although the screen is set on the front side of the object in FIG. 1, it may be set between the object and the opposite viewpoint. As will be described later, the term divergence point is used to make a unified relationship with a normal perspective projection method, etc.When the divergence point is set on the other side of the screen, the inverse perspective of the present invention is used. It means an instruction of drawing by the projection method, and in this case, the divergence point is the opposite viewpoint.

As a concrete method of setting multiple viewpoints by the inverse perspective projection method of the present invention, for example, there is a method of defining on a sphere centered on the inverse viewpoint, but the present invention is not limited to this. It is possible to define freely on any surface and realize free drawing. Further, it is possible to provide a more natural and effective three-dimensional image by applying a conventional technique such as setting a larger transparency value as the distance from the viewpoint is smaller.

According to such an embodiment, the three-dimensional image drawing method by the reverse perspective projection method of the present invention sets the viewpoint for all the objects to be drawn, and the three-dimensional image drawing method for a general object involving reflection, refraction, and transmission. It is possible to perform drawing, and it is possible to manipulate the inverse perspective projection method by freely changing the position of the reverse viewpoint in the three-dimensional space, which enables various reverse perspective drawing.

Next, an embodiment in which an ordinary perspective projection method and the above-mentioned inverse perspective projection method of the present invention are integrally associated with each other to enable generation of various images in which viewpoints and perspectives are freely set. Will be described. That is, the three-dimensional image drawing method of the present invention, as a second embodiment thereof, sets a line-of-sight direction on which an object is projected, a screen on which the object is projected, and a divergence point. If the divergence point is set to the opposite side, the object is projected and drawn on the screen by the inverse perspective projection method described above, and if the divergence point is set to the front side of the screen when viewed from the line-of-sight direction, the divergence point , The object is projected and drawn on the screen by the ordinary perspective projection method, and when the divergence point is set substantially infinitely forward or infinitely rearward of the screen as viewed from the line-of-sight direction, the object is parallel projected. It is projected and drawn on the screen.

With this unified relation, it is possible to continuously change the space drawing by normal perspective projection or parallel projection, and the space drawing by inverse perspective projection of the present invention, with the position of the divergence point as an operating condition. . That is, in the reverse perspective projection of the present invention, if the divergence point (reverse viewpoint) is set to infinity forward, the same spatial drawing as the so-called parallel projection is obtained. It is a space drawing obtained when the divergence point (viewpoint) is set to infinity backward, and the normal perspective projection method and the reverse perspective projection method of the present invention can be continuously changed through parallel projection. Become. By defining the divergence point as described above, it becomes possible to generate various images including the perspective method and the viewpoint and perspective method freely set. Infinite forward and infinite backward in the present invention do not necessarily mean academically infinite distance, and in fact, it is sufficient if the distance is such that parallel projection is performed in three-dimensional image drawing by the projection method. it is obvious.

Next, an embodiment in which a plurality of projection methods are mixed, including the inverse perspective projection method of the present invention, will be described. In the present embodiment, a step of setting a main viewpoint and a main screen for collecting a plurality of objects drawn by mixed projection methods into one image, and a tentative line-of-sight direction and a tentative line direction for temporary drawing for each object A step of setting a screen and a tentative divergence point, for each object, from the relationship between the set tentative line-of-sight direction and the tentative screen and the tentative divergence point, the inverse perspective projection method, the perspective projection method,
Alternatively, the method includes the steps of determining any one of the parallel projection methods and projecting and drawing the object on the temporary screen by the determined projection method, and projecting and drawing the temporarily drawn temporary screen from the main viewpoint to the main screen. The image projected and drawn on the main screen is a three-dimensional image.

That is, the drawing algorithm by the inverse perspective projection method of the present invention is applied in the relationship between the temporary screen and the temporary reverse viewpoint, and the ordinary perspective projection is also applied in the relationship between the temporary screen and the temporary viewpoint. Then, the projected images of the respective temporary screens are projected on the main screen and are combined into one image. An image cannot be generated without assuming a temporary screen, but in that case, when the temporary divergence point (temporary reverse viewpoint or temporary viewpoint) is far from the main viewpoint, the size of the object drawn by the temporary divergence point becomes There is a problem that the size is different from the main viewpoint. If the temporary screen is installed in the center of the object where the size of the projected image is not so changed from the main viewpoint, the effect of changing the temporary divergence point on the size of the projected image can be reduced.

According to such an embodiment, the three-dimensional image drawing method by the mixed projection method of the present invention makes a unified relation by the relation between the temporary divergence point and the temporary screen, so that the perspective and the perspective can be freely set for each object. The viewpoint can be set, and various images can be generated by freely setting the perspective and viewpoint including the reverse perspective projection method of the present invention.

The tentative line-of-sight direction, tentative screen, or tentative divergence point may be different for each object, or may be set in common for a plurality of objects, and any combination of these limits the present invention. Not something to do. Further, the three-dimensional image drawing method of the present invention is not limited to drawing only by the projection method, and can be carried out including drawing by a known technique such as drawing using a fisheye lens or panoramic effect. .

The apparatus of the present invention is a three-dimensional image drawing apparatus for drawing a three-dimensional image using the three-dimensional image drawing method of the present invention having the above-described embodiment, and the recording medium of the present invention is A computer-readable recording medium recording a three-dimensional image drawing program for realizing the function of drawing a three-dimensional image using the three-dimensional image drawing method of the present invention having the above-described embodiment.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

As a first embodiment, a three-dimensional image drawn by inverse perspective projection of a cube by the three-dimensional image drawing method of the present invention will be described. FIG. 2 is an example of the three-dimensional image, and the configuration in the virtual space of the present embodiment is a cube having a camera with a viewing angle of 67 degrees in the virtual space and a specular reflection characteristic of 1 m on a side. A plane having an infinite size of a checkered flag pattern is arranged at a point 3 m in front of the camera and arranged at a point 6 m in front of the camera, and a point light source is used as a light source and is arranged at the left rear of the camera.

In the structure in this virtual space, the screen is located 3 m in front of the camera and the divergence point is 7 m in front of the camera.
With such a setting, the three-dimensional image drawing method of the present invention makes the front of the camera the line-of-sight direction, and the divergence point set on the other side of the screen as seen from the line-of-sight direction as the opposite viewpoint on the screen. The ray tracing method is performed in the direction of the divergence point (reverse viewpoint) from each of the multiple viewpoints defined for each pixel, and the inverse perspective projection is drawn by calculating the color for each pixel of the screen.

FIG. 2 shows the configuration and settings as described above.
A three-dimensional image drawn by inverse perspective projection of a cube,
It shows that the inverse perspective projection method is used, in which the part that is farther from the camera is drawn larger, and that the plane with the checkered flag pattern is reflected on a cube with specular reflection characteristics on the surface. ing.

Next, as a second embodiment, a three-dimensional image drawn by perspectively projecting a cube by the three-dimensional image drawing method of the present invention will be described. FIG. 3 is an example of the three-dimensional image, and the configuration of the present embodiment in the virtual space is the same as that of the first embodiment. A camera with a viewing angle of 67 degrees is arranged in the virtual space and one side is 1 m. A cube with the specular reflection property of 3 is placed 3 m in front of the camera, and a plane with an infinite size of a checkered flag pattern is placed 6 m in front of the camera. The point light source is used as the light source, and the left rear of the camera is used. It was placed in.

In the structure in this virtual space, the screen is set at a point 3 m in front of the camera (same as the first embodiment).
However, the divergence point is set at the same position as the camera, and the three-dimensional image drawing method of the present invention has the divergence point set on the front side of the screen when viewed from the line-of-sight direction by the setting. Using the point as a viewpoint, the ray tracing method is performed from the divergence point (viewpoint) in each direction on each pixel on the screen, and the perspective projection is drawn by calculating the color for each pixel on the screen.

FIG. 3 shows the configuration and settings as described above.
It is a three-dimensional image drawn by perspective projection of a cube, showing that the perspective projection method is used in which the part farther from the camera is drawn smaller, and the plane with the checkered flag pattern is on the surface. The figure shows the reflection on a cube having specular reflection characteristics.

Next, as a third embodiment, a three-dimensional image drawn by parallelly projecting a cube by the three-dimensional image drawing method of the present invention will be described. FIG. 4 is an example of the three-dimensional image, and the configuration of the present embodiment in the virtual space is the same as that of the first and second embodiments, and a camera with a viewing angle of 67 degrees is arranged in the virtual space. A cube with a specular reflection characteristic of 1 m on each side is placed 3 m in front of the camera, and a plane with an infinite size of a checkered flag pattern is placed 6 m in front of the camera. The light source uses a point light source, It is located at the left rear of the camera.

In the configuration in this virtual space, the screen is set at a point 3 m in front of the camera (Examples 1 and 2).
The same as the above), and the divergence point is set to 10 km in front of the camera. With such a setting, the three-dimensional image rendering method of the present invention sets the front of the camera as the line-of-sight direction and the screen when viewed from the line-of-sight direction, as in the first embodiment. With the divergence point set on the other side as the reverse viewpoint, the ray tracing method is performed in the direction of the divergence point (reverse viewpoint) from each of the multiple viewpoints defined for each pixel on the screen, and the color for each pixel of the screen is determined. Although projection drawing is performed by calculation, this embodiment is an embodiment in which the divergence point is set substantially infinitely forward or infinitely rearward of the screen as viewed from the line-of-sight direction (in this embodiment, 10 km forward). Thus, an image obtained by projecting and drawing the object on the screen by the parallel projection method can be obtained.

FIG. 4 shows the configuration and settings as described above.
It is a three-dimensional image drawn by projecting a cube in parallel, showing that the parallel projection method is used in which it is drawn in the same size regardless of the distance from the camera. Shows that it is reflected by a cube having specular reflection characteristics on the surface.

As a fourth embodiment, a three-dimensional image drawn by applying different projection methods to three cubes by the three-dimensional image drawing method of the present invention will be described. FIG. 5 is an example of the three-dimensional image, and the configuration in the virtual space of the present embodiment is such that a camera having a viewing angle of 67 degrees is arranged in the virtual space and a cube having a specular reflection characteristic of 1 m on a side is formed. It was constructed by arranging three planes 5m in front of the camera and placing a plane with an infinite size of a checkered flag in the position 8m in front of the camera, using a point light source as the light source, and arranging it to the left rear of the camera. It is a thing.

In the configuration in this virtual space, the main screen was set at a point 5 m in front of the camera, and the three cubes and the plane were set with a temporary screen and a temporary divergence point, respectively. That is, the three cubes and the flat tentative screen are set at the same point 5 m in front of the camera (the same position as the main screen), and the tentative divergence points of the three cubes are 10 m in front of the left cube and 10 km in front of the camera. , 0 m (the same position as the camera), and the divergence point of the plane was set 10 km in front of the camera.

This embodiment is an embodiment in which the main screen and the provisional screen are set at the same position, and projection from the provisional screen to the main screen is not required, and by such setting,
According to the three-dimensional image drawing method of the present invention, the front of the camera is set as the line-of-sight direction for each object of interest, the projection method is determined from the relationship between the temporary screen and the temporary divergence point, and the temporary screen (main screen) is determined according to the determined projection method. Projection drawing is performed by calculating the color for each pixel.

FIG. 5 shows the configuration and settings as described above.
It is a three-dimensional image drawn by applying different projection methods to three cubes, the plane of the checkered flag pattern is the parallel projection method, and the three cubes are from the left, the reverse perspective projection method, the parallel projection method, and the perspective projection method. It shows that the method is performed, and that the surface of each cube is reflected by a plane with a checkered flag pattern or other cubes by specular reflection.

According to the embodiment described in detail above, it is possible to draw a general object involving reflection, refraction, and transmission by the inverse perspective projection method, and freely change the position of the inverse viewpoint in the three-dimensional space. Since it is possible to operate the inverse perspective projection method, it is possible to perform various kinds of inverse perspective drawing. In addition, by defining the divergence point, it is possible to generate various images including the perspective and the perspective, and freely setting the viewpoint and perspective. Furthermore, it is possible to generate a wide variety of images in which the perspective and the viewpoint are freely set for each object by making a unified relation by the relation between the temporary divergence point and the temporary screen. Although the embodiments of the present invention have been described above, it is obvious that various changes may be made in the form and details without departing from the spirit and scope of the present invention defined in the claims. . For example, as an example of the three-dimensional image drawing method by the mixed projection method, Example 4 in which the main screen and the temporary screen are set at the same position has been described, but the main screen and each temporary screen are set at different positions, For each object, projection drawing is performed on the temporary screen by the determined projection method, and the provisionally drawn temporary screen is projected and drawn on the main screen from the main viewpoint, so that more various images can be generated.

[0040]

According to the present invention, the reverse viewpoint seen from multiple viewpoints is set on the other side of the screen, and the object is projected on the pixel for each pixel of the screen with the straight line connecting the pixel and the divergence point as the line of sight. It obtains a three-dimensional image of the inverse perspective projection method, and can draw a general object with reflection, refraction, and transmission. Also, the inverse perspective projection method can be used by changing the position of the inverse viewpoint in the three-dimensional space. Since it can be operated, there is an effect that various reverse perspective drawing is possible. Furthermore, since the divergence point is set as an operation condition, and this can be used as the reverse viewpoint or viewpoint, the space drawing by the reverse perspective projection, perspective projection, or parallel projection can be continuously changed, and thus the reverse perspective projection method is included. This has the effect of enabling the generation of various images with the viewpoint and perspective set freely.

[Brief description of drawings]

FIG. 1 is a conceptual diagram for explaining the principle of a three-dimensional image drawing method by the reverse perspective projection method of the present invention.

FIG. 2 is an example of a three-dimensional image drawn by performing inverse perspective projection of a cube by the three-dimensional image drawing method of the present invention.

FIG. 3 is an example of a three-dimensional image drawn by perspective projection of a cube by the three-dimensional image drawing method of the present invention.

FIG. 4 is an example of a three-dimensional image drawn by projecting a cube in parallel by the three-dimensional image drawing method of the present invention.

FIG. 5 is an example of a three-dimensional image drawn by applying different projection methods to three cubes by the three-dimensional image drawing method of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tetsuya Harada             2-16-1 Tokiwadai, Ube City, Yamaguchi Prefecture Yamaguchi             College of Engineering F-term (reference) 5B080 BA07 GA06

Claims (6)

[Claims] 1. A three-dimensional image drawing method by a computer for projecting and drawing an object in a three-dimensional space on a screen, a viewing direction for projecting the object, a screen for projecting the object, and a screen for viewing the screen in the viewing direction. A divergence point is set on the far side (front side), and the divergence point is projected and drawn on each pixel of the screen with the straight line connecting the pixel and the divergence point as the line of sight. A three-dimensional image drawing method by the inverse perspective projection method, which is characterized by an inverse viewpoint. 2. A three-dimensional image drawing method by a computer for projecting and drawing an object in a three-dimensional space on a screen, wherein a line-of-sight direction for projecting the object, a screen for projecting the object, and a divergence point are set, and the divergence point is set. When the point is set on the other side (front side) of the screen when viewed from the line-of-sight direction, the divergence point is set as an inverse viewpoint, and the object is projected and drawn on the screen by the inverse perspective projection method according to claim 1. The divergence point is the front side (rear side) of the screen when viewed from the line of sight.
When set to, the three-dimensional image drawing method is characterized in that the object is projected and drawn on the screen by the perspective projection method with the divergence point as a viewpoint. 3. When the divergence point is set substantially infinitely forward or infinitely rearward of the screen as viewed from the line-of-sight direction, the object is projected and drawn on the screen by a parallel projection method. The three-dimensional image drawing method according to claim 1 or 2. 4. A step of setting a main viewpoint and a main screen for gathering a plurality of objects drawn by mixed projection methods into one image, and a tentative line-of-sight direction and a tentative screen for temporary drawing for each object. And a step of setting a temporary divergence point,
For each object, a projection method of the inverse perspective projection method, the perspective projection method, or the parallel projection method is determined from the relationship between the provisional line-of-sight direction, the provisional screen, and the provisional divergence point set. Projecting and drawing on the main screen by projecting and drawing the object on the temporary screen by the determined projection method, and projecting and drawing the temporarily drawn temporary screen on the main screen from the main viewpoint. A three-dimensional image drawing method, wherein the obtained image is a three-dimensional image. 5. A three-dimensional image drawing device that draws a three-dimensional image using the method according to claim 1. 6. A computer-readable recording medium recording a three-dimensional image drawing program for realizing a function of drawing a three-dimensional image by using the method according to claim 1.