JP3931375B2 - Image forming method using polygon and image processing apparatus using this method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming an image model such as terrain using polygons and an image processing apparatus using the method, and more particularly to a method for forming an image model using polygons based on vertex data of one polyhedron and the method. The present invention relates to an image processing apparatus.
[0002]
[Prior art]
In recent years, image processing apparatuses that display images of objects arranged in a virtual three-dimensional space using computer graphic technology have become widespread, and research and development of virtual reality has been promoted in order to display display objects closer to reality. ing.
[0003]
In such computer graphic technology, an object in a virtual three-dimensional space is displayed by being composed of a plurality of polygonal surfaces, so-called polygons. Further, an image model such as complicated terrain is displayed with a plurality of polygons.
[0004]
FIG. 10 is a diagram illustrating a topographic image as an example of a complex image model displayed with polygons. Three-dimensional coordinates are given to the vertices of a plurality of polygons constituting the terrain to form terrain image data. For example, the polygon A has vertices a1, a2, and a3, and the polygon B has vertices b1 (= a2), b2, b3, and b4. Further, the polygon C has vertices c1 (= b3), c2, c3, and c4, and the polygon D has vertices d1 (= b4), d2 (= c1), d3 (= c4), and d4.
[0005]
Therefore, as the image model such as terrain becomes more complex, the number of polygons increases, and the vertex coordinate data of each polygon becomes enormous. For this reason, when displaying the state of the sea surface and the undulations of the ground surface, etc., where the fineness is not necessarily required for the display image, the data for image formation increases and the design takes a considerable time.
[0006]
[Problems to be solved by the invention]
Accordingly, it is an object of the present invention to provide an image forming method using polygons and an image processing apparatus using the method, which can form an image model with a simple procedure.
[0007]
Further, an object of the present invention is to provide an image forming method using polygons and an image processing apparatus using this method that can form a complex image model by repeatedly preparing only predetermined vertex data and transforming it. It is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, as a basic configuration of an image forming method using polygons according to the present invention, three-dimensional coordinate data is assigned to each vertex of one polyhedron in a virtual three-dimensional space in an image forming method using polygon data. Identifying and translating coordinate data corresponding to a two-dimensional plane formed by two orthogonal axes among the three-dimensional coordinate data specified for each vertex, and arranging a plurality of polyhedra on the two-dimensional plane; Each of the arranged polyhedrons is rotated by a predetermined angle so that an image model is represented by a plurality of polygons appearing on the surface.
[0009]
Furthermore, the gap generated in the plurality of polyhedrons arranged in the two-dimensional plane is filled with texture data having values obtained from the texture data for each surface of the polyhedron, if necessary.
[0010]
In this case, the texture data of values obtained from the texture data for each surface of the polyhedron can be easily set to the average value of the texture data for each surface of the polyhedron.
[0011]
Further, when the polyhedron is a rectangular parallelepiped, three-dimensional coordinate data is specified for each vertex of one rectangular parallelepiped in the virtual three-dimensional space, and two orthogonal axes among the three-dimensional coordinate data specified for each vertex. The coordinate data corresponding to the two-dimensional plane formed by the above are translated, and adjacent to each other so that at least some of them overlap each other, a plurality of rectangular parallelepipeds are sequentially arranged on the two-dimensional plane, and the arranged Each of the plurality of rectangular parallelepipeds is rotated by a predetermined angle, and an image model is represented by a plurality of polygons appearing on the surface.
[0012]
In this way, by arranging a plurality of rectangular parallelepipeds on a two-dimensional plane based on the three-dimensional coordinate data of each vertex of a polyhedron, typically a rectangular parallelepiped, and rotating them, it is easy with less data and simple processing. An image model using polygons can be formed.
[0013]
Furthermore, the arbitrary rectangular parallelepipeds arranged in order adjacent to each other are shifted in a third axial direction perpendicular to the two orthogonal axes, and then each of the plurality of rectangular parallelepipeds is rotated by a predetermined angle. Like that. Thereby, a more complicated image model can be easily formed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or similar elements are denoted by the same reference numerals or reference symbols.
[0015]
FIG. 1 is a block diagram showing the configuration of an image processing apparatus to which an image forming method using polygons according to the present invention is applied.
[0016]
In FIG. 1, a CPU 1 controls execution of a program for processing an image displayed by polygons. The CPU 1 is connected to a data buffer 2 which is a memory for temporarily storing vertex data of polygons and register set functions displayed on the display device 8 as the program proceeds.
[0017]
The feature of the present invention is that the vertex data of the polygon corresponding to the terrain image model displayed on the display device 8 stored in the memory is easily generated. In FIG. 1, a geometry processing unit 3 for arranging a polygon in a three-dimensional space according to the vertex data and converting it into a two-dimensional coordinate system for display on the display device 8 is connected to the data buffer 2. ing.
[0018]
Further, a rendering processing unit 4 that performs coloring, shading, and texture pasting is connected to each polygon to be displayed. A frame buffer 7 is connected to the output side of the rendering processing unit 4, and data for one screen to be displayed is stored. A display device 8 such as a CRT is connected to the frame buffer 7, and the contents of the frame buffer 7 are sequentially displayed.
[0019]
Here, the geometry processing unit 3 receives polygon vertex data (vertex coordinates, vertex colors, texture map coordinates, vertex transparency, vertex normal vectors, etc.) from the data buffer 2 in accordance with the progress and processing speed of the program. Read) and register set functions.
[0020]
The geometry processing unit 3 arranges polygons in the three-dimensional space based on the vertex coordinate data, determines the viewport to which area of the three-dimensional space is to be displayed, calculates the luminance of each vertex based on the normal vector, etc. I do. Further, the polygon vertices that protrude from the viewport are removed, that is, clipping is performed. Further, the polygon arranged in the viewport is projected onto the secondary plane with reference to a predetermined viewpoint, and coordinate conversion from 3D to 2D is performed.
[0021]
The polygon data coordinate-converted into two-dimensional coordinates is sent to the rendering processing unit 4. The rendering processing unit 4 includes a filling circuit, a texture pasting circuit, a depth test circuit, and a blending circuit (not shown).
[0022]
The filling circuit has a function of calculating information of pixels (pixels) in a range surrounded by the vertices of the polygon and passing the information to each circuit in the other rendering processing unit 4. In the above calculation, for example, linear interpolation is performed on the pixel information between the vertices of the polygon based on the vertex information (vertex coordinates, vertex luminance, vertex color, etc.) given to both corresponding vertices.
[0023]
The texture pasting circuit is a circuit that reads out the texture at the address position corresponding to the coordinates of the pixel from the texture map 5 and calculates the color of the pixel. The depth test circuit is a circuit that compares the context of a plurality of polygons and stores the data of the polygon arranged at the forefront in the depth buffer 6.
[0024]
That is, the depth buffer 6 stores the Z value of the pixel of the figure (polygon) drawn earlier. In particular, when considering polygon data generated according to the present invention, when a rectangular parallelepiped is considered as an example of a polyhedron, as will be described later, a surface of adjacent rectangular parallelepipeds may intersect due to rotation of the rectangular parallelepiped.
[0025]
Therefore, a part of the surface of the rectangular parallelepiped enters the surface of the adjacent rectangular parallelepiped and is hidden by the surface of the adjacent rectangular parallelepiped. In such a case, a portion hidden by the adjacent rectangular parallelepiped surface is not displayed. This hidden portion has a depth value larger than that of the adjacent rectangular parallelepiped surface and is on the far side.
[0026]
In this way, the depth values of the polygons are compared, and the corresponding polygon data is stored in the depth buffer 6 so that the polygon located at the front of the comparison is the display target.
[0027]
When a new polygon is displayed at a position overlapping with the previously drawn polygon on the screen, the Z value of each pixel constituting the new polygon and the pixel of the previously drawn polygon read from the depth buffer 6 are displayed. Compare with Z value. As a result of the comparison, if the pixel of the new polygon is in front, the Z value of the pixel is written in the depth buffer 6.
[0028]
The blending circuit mixes the color information of the previously drawn polygon pixel read from the frame buffer 7 and the color information of the newly processed polygon pixel, and writes it again into the frame buffer 7. The information in the frame buffer 7 is sent to the display device 8 for each screen and displayed.
[0029]
Next, an embodiment in which image model data by polygons processed for image display is formed according to the present invention in the image processing apparatus configured as described above will be described.
[0030]
In the following description of the embodiments, an image model will be described by taking a terrain image as an example, but the present invention is not limited to such an image model. The present invention can also be applied to display of a sea surface image, a tree skin image, and the like.
[0031]
FIG. 2 is a processing flow of an embodiment of a method for forming terrain image data by polygons according to the present invention. In the description of the present invention, a reference object is called an object. A rectangular parallelepiped is assumed in the virtual three-dimensional space as an example of the object (step S1). This object has 8 vertices and 6 faces. Accordingly, the three-dimensional coordinate data for each of the eight vertices is specified.
[0032]
Next, a plurality of these objects are translated and arranged on the two-dimensional plane in the two-axis direction of the three-dimensional coordinates (step S2). This is possible by parallel shifting by sequentially shifting the coordinate values in the biaxial direction of the rectangular parallelepiped assumed in the virtual three-dimensional space, and arranging a plurality of rectangular parallelepipeds in a planar shape. At this time, the adjacent rectangular parallelepipeds of a plurality of rectangular parallelepipeds arranged in a plane are arranged so as to overlap each other.
[0033]
Such a situation is shown in FIG. That is, in FIG. 3, the rectangular parallelepiped 10 is assumed in the virtual three-dimensional space. A plurality of rectangular parallelepipeds are arranged on the two-dimensional plane 100 in the x and z axis directions by translating the rectangular parallelepiped 10 in the x and z axis coordinate directions.
[0034]
In FIG. 3, in the state where a plurality of rectangular parallelepipeds are arranged on the two-dimensional plane 100 in the x and z axis directions, reference numerals 101 and 102 are examples of portions where adjacent rectangular parallelepipeds overlap each other.
[0035]
Next, returning to the flow of FIG. 2, a plurality of rectangular parallelepipeds arranged on the two-dimensional plane 100 in the x and z axis directions are respectively rotated (step S3). Preferably, the rotation is performed so that the sides are not parallel to the Y axis. Thereby, the positions in the Y-axis direction of the vertices of a plurality of rectangular parallelepipeds arranged on the two-dimensional plane 100 in the x- and z-axis directions are not the same, and the heights are different.
[0036]
Further, the portion of each surface of the rectangular parallelepiped that appears on the surface of the figure formed in this way is set as polygon data, and these polygon data are explained by the geometry unit 3 and the rendering unit 4 through the data buffer 2 of FIG. By performing the computer graphic processing, a topographic image is displayed on the display device 8 as in the display screen example shown in FIG.
[0037]
Next, for better understanding of the present invention, the present invention will be described by way of specific examples. FIG. 5 shows an example in which a rectangular parallelepiped is used as the object. Therefore, the cube has eight vertices (1) to (8) and six faces.
[0038]
The coordinate data of the vertices (1) to (8) is a coordinate system with the center of the object as the origin, called the object coordinate system, and is a value represented by (x, y, z). Further, the surface data (square in the example of FIG. 5) is represented by the numbers of the four vertices constituting the surface, for example, (p 1, p 2, p 3, p 4).
[0039]
Further, FIG. 6 is a diagram showing a process of executing the procedure of FIG. 2 based on the object of FIG. 5, and as an example, an example in which four objects are arranged on a two-dimensional plane of the xz axis. FIG. The row (a) in FIG. 6 is a view seen from above, and the row (b) in FIG. 6 is a view when observed from an oblique direction.
[0040]
The objects shown in FIG. 5 are translated in the x-axis direction and the z-axis direction (2 × 2 in the vertical direction) so as to be arranged [see FIGS. 6 (1) to (3)]. At this time, the adjacent objects are arranged so as to overlap each other.
[0041]
Now, when the translation amounts in the x-axis direction and the z-axis direction are Mx and Mz, respectively, the coordinates after translation of one vertex (x, y, z) of the object are (x + Mx, y, z + Mz). Become. The parallel movement amounts Mx and Mz are the same for all vertices in the same object.
[0042]
In this way, when the object is translated in the x-axis direction and the z-axis direction to be 2 × 2 vertically, the number of vertex data is 8 × 4 = 32 and the number of surface data is 6 ×. 4 = 24.
[0043]
Next, the arranged objects are rotated (see FIGS. 6 (4) to (5)). Each object is rotated at an arbitrary angle with respect to the x, y, and z axes of the object coordinates. The rotation is performed for each object.
[0044]
When the x-axis rotation angle of the object is Rx, the coordinates of the coordinates (x, y, z) of the point in the object after the x-axis rotation are
(X, y x cosRx + z x sinRx, -y x sinRx + z x cosRx)
It becomes.
[0045]
Similarly, if the angle of y-axis rotation is Ry, the coordinates after y-axis rotation are
(X × cosRy−z × sinRy, y, x × sinRy + z × cosRy)
It becomes. In addition,
Similarly, if the angle of z-axis rotation is Rz, the coordinates after z-axis rotation are
(X x cosRz + y x sinRz, -x x sinRz + y x cosRz, z)
It becomes.
[0046]
Furthermore, when rotating about a some axis | shaft, what is necessary is just to perform each rotation in order according to said relationship. Rx, Ry, and Rz are constant at all points in the same object.
[0047]
FIG. 7 is a view of the model generated as described above as viewed from above. The vertices surrounded by ○ are generated by overlapping objects, and there is no vertex data. On the other hand, the advantage of not increasing the amount of data according to the present invention can be easily understood as compared with the conventional method that requires data for all vertices including such vertices.
[0048]
Here, in general, in a computer graphic technique, a polygon constituting an object is generally a triangle or a quadrangle. Therefore, as shown in FIG. 7, the surface constituting the terrain model is not limited to a quadrangular shape, but when it is a polygon other than a triangular shape and a quadrangular shape, it is divided into a plurality of triangular shapes and / or quadrangular shapes. It is necessary to have as plane data separately.
[0049]
For this reason, in the conventional method, the vertex data is further increased, but the problem that the vertex data is increased according to the present invention can also be avoided.
[0050]
FIG. 8 is a further embodiment of the expansion of the present invention. A plurality of objects arranged in a plane as shown in FIG. 6 (3) are arbitrarily translated in the y-axis direction before rotating (see FIG. 8 (a)).
[0051]
Accordingly, after arbitrary translation in the y-axis direction, as described in FIGS. 6 (4) and (5), by rotating the object, a more complex model can be obtained as shown in FIG. 8 (b). It is possible to form.
[0052]
Furthermore, in the above-described embodiments and examples, it has been described that adjacent objects are overlapped when the object is translated along the x-axis and the z-axis. As a result, the objects overlap and it is possible to easily create a complicated shape. Further, the reason why the adjacent objects are translated so as to overlap each other is to prevent a gap from being generated between the objects when the objects are not rotated.
[0053]
However, when a complicated shape is generated more easily, it is not always necessary to translate the adjacent objects so as to overlap each other. Furthermore, in the present invention, the basic object is not limited to a rectangular parallelepiped. It is also possible to use a tetrahedron that is a triangular pyramid or a polyhedron that is larger than six sides with respect to a rectangular parallelepiped.
[0054]
In this case, a gap may be generated between the objects when the objects are arranged and rotated. Accordingly, it is also possible to fill the gaps between the objects with, for example, the average value of the texture data of the polygons constituting the objects.
[0055]
FIG. 9 is a diagram for explaining another response to the possibility of a gap between objects when objects are arranged and rotated, and is an example using a triangular pyramid as a polyhedron.
[0056]
FIG. 9 shows a state in which the triangular pyramids 100 are arranged and rotated in the same manner as described in the example of the rectangular parallelepiped earlier. The triangular pyramid 100 is composed of four polygonal surfaces and has five vertex coordinates. Accordingly, a polygonal image can be formed only by changing the five vertex coordinates depending on the arrangement and rotation state of the triangular pyramid 100.
[0057]
Further, in FIG. 9, a gap 104 is generated between the plurality of arranged triangular pyramids 100. Therefore, a predetermined gap filling polygon 10 is prepared. In FIG. 9, wavy line portions 101, 102, and 103 below the triangular pyramid 100 are located in the lower part of the polygon 10 for gap embedding at the clipping stage for setting the image display area, and are the non-displaying portions of the triangular pyramid 100. This is the polygon area.
[0058]
Since predetermined texture data is given to the polygon 10, the gap 104 generated between the plurality of triangular pyramids 100 is embedded with predetermined texture data for the polygon 10. At this time, the predetermined texture data for the polygon 10 is made the same as or similar to the texture data of the polygon constituting the triangle pyramid 100, so that the continuity of the plurality of triangle pyramids 100 and the polygon 10 can be maintained.
[0059]
The vertex coordinates A, B, C, and D of the gap-filling polygon 10 may be set so as to be perpendicular to the clipping plane at the above-described clipping stage for setting the image display area, for example.
[0060]
In the example of FIG. 9, only one gap filling polygon 10 is shown. However, as long as simplification is not hindered, a plurality of gap filling polygons should be crossed at a predetermined angle. Is also possible.
[0061]
【The invention's effect】
As described above with reference to the drawings, according to the present invention, it is possible to perform the process of translating and rotating an object in units of objects without performing the process for each vertex. For this reason, the number of processing steps can be reduced.
[0062]
Furthermore, by applying the present invention, it is possible to form an object such as a topography, a water surface, a tree surface, etc. with polygons with a simple operation and a small amount of data.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image processing apparatus to which a terrain image forming method using polygons according to the present invention is applied.
FIG. 2 is a processing flow of an embodiment of a method for forming terrain image data by polygons according to the present invention;
FIG. 3 is a diagram illustrating a process of arranging a plurality of objects on a two-dimensional plane in a two-axis direction of three-dimensional coordinates in the method of the present invention.
FIG. 4 is a diagram showing an example of a state when a topographic image is displayed on a display and is a time chart.
FIG. 5 is a diagram illustrating an example in which a cuboid is a cube as an object;
6 is a diagram illustrating a process of executing the procedure of FIG. 2 based on the object of FIG. 5, and illustrates an example of arranging four objects on a two-dimensional plane of an xz axis as an example. It is.
FIG. 7 is a diagram illustrating a state where a model generated according to the present invention is viewed from above.
FIG. 8 is a diagram for explaining how the object is further translated in the y-axis direction according to an embodiment of the extension of the present invention.
FIG. 9 is a diagram illustrating a response when a gap is generated between objects.
FIG. 10 is a diagram illustrating an example of complex terrain displayed with polygons.
[Explanation of symbols]
1 CPU
2 Data buffer 3 Geometry processing unit 4 Rendering processing unit 5 Texture map 6 Depth buffer 7 Frame buffer 8 Display

Claims (4)

In accordance with a program executed by the image processing apparatus, a method of forming a more terrain image into polygon data,
The geometry processing unit,
The polyhedron three-dimensional coordinate data on each vertex is formed by a plurality of polygons are specified, two orthogonal axes X in the virtual three-dimensional space, and a plurality pieces arranged step in a plane in a two dimensional plane formed by the Z ,
And rotating each of the plurality of polyhedrons which are arranged a plurality of said planar, three axial directions X coordinate of a point in said polyhedron, Y, respectively Rx, Ry, at an angle of Rz relative Z,
Comprising the step of converting said rotated plurality of models formed by polyhedron, projected to the two-dimensional coordinate data in a two-dimensional plane based on the viewpoint of the virtual three-dimensional space,
In addition, the rendering processor
Performing a rendering process of pasting a terrain texture on the two-dimensional coordinate data projected onto the two-dimensional plane ;
Method of forming a topographical image by polygon data, characterized in that it comprises a. According to claim 1,
A method for forming a topographic image using polygon data , wherein, in the step of arranging a plurality of polyhedrons by the geometry processing unit , at least a part thereof is arranged adjacent to each other so as to overlap each other. According to claim 1,
Further, by the geometry processing section, a gap generated plurality of polyhedron arranged in the two-dimensional plane, by the polygon data, characterized by comprising the step of embedding polygon for implantation gap predetermined texture data is given the method of forming the terrain image. A CPU that controls execution of a program, and a recording that stores a program for converting a polyhedron in which 3D coordinate data is specified at each vertex of the polygon into 2D coordinate data by executing execution control of the program by the CPU. A medium,
The program is
To the CPU,
The geometry processing unit,
A plurality of polyhedrons in which three-dimensional coordinate data is specified at each vertex of the polygon are arranged in a plane on a two-dimensional plane formed by two orthogonal axes X and Y in a virtual three-dimensional space, and further arranged. a step of each of the plurality of polyhedrons, each Rx, Ry, Ru is rotated at an angle of Rz 3 axial direction X of the coordinates of the points of the multi surface body, Y, with respect to Z,
A step of said rotated plurality of models formed by polyhedron, Ru is converted by projecting a two-dimensional plane based on the viewpoint of the virtual three-dimensional space into a two-dimensional coordinate data,
In addition, the rendering processor
Performing a rendering processing a texture of the terrain to the two-dimensional coordinate data,
A recording medium storing a program characterized in that execution control is performed .

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