JP3143208B2 - Simulated view generation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating a simulated visual field using a computer.

[0002]

2. Description of the Related Art In computer graphics, a necessary pattern is added to a polygonal surface constituting an assumed three-dimensional scene stored in a database and displayed as a two-dimensional image viewed from a specified viewpoint. There is a way to do. A necessary pattern on a polygon (referred to as a “polygon”) constituting a scene is called a texture, and refers to a complicated and uneven pattern of color and brightness. Each polygon is composed of planes one by one, and is displayed by performing parallel rotation movement so as to be a scene that looks at the plane on the database from the viewpoint,
If no texture is given, the surface of the sea or the ground is displayed as a simple blue or brown plane. FIG. 8A shows a display example of a sea surface without a texture, and FIG. 8B shows a display example of a sea surface with a texture.

[0003] Such a texture is mainly given for the following reason.

[0004] First, as can be seen from FIG.
The image can be made to be realistic close to the real world.

Second, when a training simulator for an airplane, a car, or the like is configured by applying computer graphics, a trainee such as a pilot can be more accurately given a sense of speed, a sense of distance, and the like.

Third, since a complicated pattern expression can be generated without using polygons, the amount of hardware calculations can be reduced. And so on.

[0007] The principle of texture generation is to associate each pixel on the CRT as a display device with an address of a texture memory in which a pattern is stored in advance, in a path reverse to that of a normal polygon. This operation is called "mapping".

FIG. 9 shows the conversion of the normal simulated visual field generation, and FIG.
Fig. 1 schematically shows the procedure of the inverse transformation used in texture mapping.

FIG. 9 shows a normal conversion, that is, a process of converting a polygon defined in a database coordinate system into screen coordinates. The vertex (for example, one point of the cube in FIG. 9) defined in the database coordinate system is subjected to translation and rotation conversion in accordance with the pilot's viewpoint position and orientation, and is converted to the viewpoint coordinate system. The vertex converted into the viewpoint coordinate system is further subjected to a geometric process for allowing a polygon surrounded by the vertex to be seen from the viewpoint, that is, a perspective transformation, and is converted into screen coordinates. That is, a point (X _e , Y _e ,
Z _e ) is converted to a point (X _P , Y _P , Z _P ) in the viewpoint coordinate system by parallel and rotational movement, and further converted to screen coordinates (X _S , Y _S ) by perspective transformation.

On the other hand, texture mapping is
It is expressed as an inverse transformation from the screen coordinates (X _S , Y _S ) as shown in FIG. 10 to the database coordinate system. As shown in the flowchart of FIG. 11, the conversion from the screen coordinates to the earth coordinate system is as follows. Each pixel on the CRT, that is, one point (X _S , Y _S ) on the screen coordinates is, for example, a point (X
_P , Y _P , Z _P ), and by rotation and translation, a point (X _e , Y _e ,
After being transformed into Z _e ), it is transformed into texture coordinates (X _T , Y _T ) by texture space mapping for orthogonal projection to the assumed horizontal plane, that is, the texture plane.
(X _T , Y _T ) is given screen coordinates (X _S ,
Y _S , Z _S ) is the address of a memory in which a texture pattern is stored in advance to obtain a texture value corresponding to the texture value.

The relationship between the coordinates (X _S , Y _S , Z _S ) on the screen and one point (X _e , Y _e , Z _e ) on the earth coordinates is as follows.

[0012]

(Equation 1)

Where

[0014]

(Equation 2)

Is a viewpoint coordinate expressed in the earth coordinate system.

[0016]

(Equation 3)

A matrix is determined from the screen direction and the screen size with respect to the earth coordinate system.

[0018] Even if the viewpoint is moved by such an inverse conversion being performed accurately, the texture pattern given on the polygon is displayed on the CRT as if it were attached to the polygon. be able to.

As shown in FIG.
The case of mapping to 1 is taken as an example. The origin 1202 of the texture expressed in the earth coordinate system is (X _TO , Y _TO , Z _TO )
Then, the texture coordinates (X _T , Y _T ) are as follows. The texture is read from a texture memory (not shown) by designating the texture coordinates (X _T , Y _T ) of the texture plane 1203 as an address.
Note that reference numeral 1204 denotes a viewpoint (coordinates (X _O , Y _O , Z _O ));
205 is a screen, 1206 is the origin of the earth coordinate system.

[0020]

(Equation 4)

M _T : Texture mapping matrix

Here, as shown in FIG. 12, when the texture is orthogonally projected on the ground,

[0023]

(Equation 5)

## EQU1 ##

In the conventional texture mapping, the inverse mapping is performed on each pixel on the polygon on which the texture displayed on the CRT is defined, and the texture mapping is performed by obtaining the texture pattern value.

[0026]

In the conventional method, a texture pattern is mapped so that it looks fixed on the terrain. Therefore, in the case where the texture pattern moves, it cannot be realized, for example, for a landing light from an aircraft or a vehicle in which headlights of a car move on the ground.

An object of the present invention is to provide a method of generating a simulated view that enables a simulation of a landing light or the like by mapping a luminance pattern that dynamically changes with movement of a viewpoint onto the terrain. It is in.

[0028]

According to the present invention, there is provided a method for generating a simulated visual field according to the present invention, in which a required pattern is added to a polygonal surface constituting a supposed three-dimensional scene stored in a database and designated. In a simulated view generation method for displaying as a two-dimensional image viewed from a viewpoint, light emitted from a light source having directivity provided by a assumed moving object always exists at a fixed distance from a viewpoint position , and a direction is set to the viewpoint. Move with
A brightness pattern formed when illuminating a light plane assumed to move is stored in a pattern memory in advance, and a position on a screen surface is inversely transformed into coordinates on the earth assumed by a database viewed from a viewpoint, and the light plane The position when projected onto the coordinate point on the earth is obtained as an address of the pattern memory, and is displayed as light illumination at the coordinate point on the earth based on the luminance pattern read from the pattern memory.

[0029]

Since the light plane is always assumed to be at a fixed position from the viewpoint, the light emitted from the light source at the position of the viewpoint always illuminates the light plane with the same luminance pattern. This is stored in the pattern memory in advance. When the terrain projected on the screen surface of the display device changes as the viewpoint moves, the light plane illuminated by the same luminance pattern always moves. The position of the scene on the screen is transformed into the coordinates on the earth assumed by the database viewed from the viewpoint. By projecting the point on the earth coordinates from the light plane, the points on the light plane correspond to the points on the earth coordinates displayed on the screen surface. The pattern memory is read by using the corresponding coordinates as addresses. The read luminance pattern data is treated in the same way as the data from the corresponding coordinate point on the earth, and when the terrain is viewed from the viewpoint, the light from the light source is converted to illuminate the terrain, and the screen Displayed on the surface.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a simulated visual field generating method according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram illustrating one embodiment. FIG. 2 is a flowchart showing the procedure. Converting the screen coordinates (X _S , Y _S , Z _S ) (Z _S = 1) to the earth coordinates is the same as the method described as the related art, and is described by the above-described equation (1).

In a virtual earth space, for example, there is a viewpoint 11 of a pilot of an aircraft, which moves according to the pilot's operation. The light source 12 is located at substantially the same position as the viewpoint 11 and moves together with the viewpoint 11. The light source 12 has directivity and illuminates in a certain direction. In the present invention, the light plane 13 is a characteristic concept. The light plane 13 shown in FIG. 1 is a virtual plane corresponding to a memory that holds the shape and luminance of the light illumination from the light source 12, and does not exist in the space of the earth coordinates in the database. In the case of the embodiment, it is considered that the luminance pattern 14 by the circular light illumination from the light source 12 is held. The orientation and position of the light plane 13 are
It is defined by a light vector L that coincides with a perpendicular drawn from 1 to the light plane 13, and its direction (vector L) is defined as the direction in which the light source 12 illuminates. Distance from origin 130 of light plane 13 to viewpoint 11 |
L | is always constant, and its direction moves with the viewpoint 11 and can be changed independently. The pilot sees a two-dimensional image in which a scene on the earth coordinates is projected on the screen 15 from the viewpoint 11 through the screen 15. In addition, 16 is the origin of the earth coordinate system.

As described above, the screen coordinates (X _S ,
Y _S , Z _S ) (Z _S = 1) is converted into earth coordinates (X _e , Y _e , Z _e ) by equation (1). Next, the origin of the light plane 13 defined in the earth coordinate system is defined as (X _LO ,
Y _LO , Z _LO ), the screen coordinates (X _S , Y _S , Z
Coordinates on the light plane 13 in _{S) (X L, Y L} )
Is

[0033]

(Equation 6)

Here,

[0035]

(Equation 7)

M _T : Matrix indicating the orthogonal projection from the light plane to the ground.

[0037]

(Equation 8)

M _L : matrix indicating the attitude of the light plane with respect to the earth coordinate system. It is calculated by the light vector L.

Can be expressed as follows.

The state of projection at this time is such that the shape of the light is orthogonally projected from the light plane 13 onto the terrain constituted by the polygon 17 as shown in FIG. Therefore, the luminance pattern 1 illuminated by the light plane 13
4 is circular, and if the light plane 13 is parallel to the polygon on the earth plane, the light illumination on the polygon will be a circle, and if it is oblique, it will be an ellipse.

According to equations (2) and (3), the value of (X _L , Y _L ) can be expressed in the following form.

[0042] _{X L = a 0 + (a} 1 X S + a 2 Y S + a 3) / Z S (4)

Y _L = b ₀ + (b ₁ X _S + b ₂ Y _S + b ₃ ) / Z _S (5)

Here, a ₀ , a ₁ , a ₂ , a ₃ , b ₀ , b ₁ ,
b ₂ and b ₃ are constants for each frame.

On a plane,

Z _S = c ₁ X _S + c ₂ Y _S + c ₃ (6)

There is the following relationship.

[0048] (X _L, Y _L) to coordinate transformation the screen coordinates _{(X S, Y S, Z} S) as address (X _L, Y _L), the memory constituting the light plane 13 to access. The shape and brightness value of the light illumination are stored in the memory in advance. This memory has a capacity enough to hold, for example, a luminance pattern of a landing light, and when (X _L , Y _L ) is out of the range of light illumination, the luminance value is minimized. Read out (X _L, Y _L)
Is added to the luminance of the corresponding background (corresponding terrain surface) as a point having the luminance at the corresponding earth coordinate point to obtain a video signal.

Next, a simulated visual field generating device used in the present invention will be described with reference to FIG. The digital computer 301 and the video computer 302 shown in FIG. 3 are the same as those used for conventional texture calculation. The landing light generator 320 is a newly added device.

The digital computer 301 calculates a matrix or the like based on the above-described principle, and calculates equations (4) and (4).
The respective constants shown in (5) and (6) are calculated.

The video signal calculator 302 is the same as that used in the conventional simulated view generator, and calculates the color at the screen coordinates (X _S , Y _S , Z _S ).

The matrix accumulators 311a and 311
1b, respectively, based on the calculated constants in a digital computer _{301, a 1 X S + a} 2 Y S + a 3, b 1 X S + b 2 Y S
+ B ₃ is calculated.

From the equation of the plane to be mapped, the Z inverter 303 calculates ₁ / Z _s = 1 / (c ₁ X _s + c ₂ Y _s + c
The calculation of ₃ ) is performed, and is also used in the case described as a conventional technique.

The multipliers 313a and 313b calculate a ₁ calculated by the matrix accumulators 311a and 311b.
And _{X S + a 2 Y S +} a 3, b 1 X S + b 2 Y S + b 3, a multiplication with 1 / Z _s from Z inverter 303 performs.

The address generators 314a and 314b add constants a ₀ and b ₀ to the values multiplied by the multipliers 313a and 313b, respectively, and as shown in equations (4) and (5), X _L , Calculate the values of Y _L respectively.

The limiters 315a and 315b determine whether X _L and Y _L calculated by the address generators 314a and 314b are coordinate values outside the predetermined coordinates of the luminance pattern. Is sent to the pattern memory 316 at the address having the minimum luminance.

The pattern memory 316 is a memory for storing a luminance pattern, and stores the illumination shape and the luminance distribution when the light plane is illuminated by the light source. FIG. 4 schematically shows the state.

The attenuation table 317 is a table for attenuating the brightness of the light plane read from the pattern memory 316 so as to have an appropriate brightness according to the distance from the viewpoint to the top of the terrain. This attenuation table 317
In accordance with an instruction from the digital computer 301, on / off control of the light source is also performed. When the light source is turned off, the brightness becomes the minimum value.

When simulating a plurality of light sources whose directions can be changed, an overlapping portion is formed due to the light directions of the two light sources. Make it higher by doing. In the case where a plurality of light sources are provided, a plurality of landing light generating devices 320 surrounded by dotted lines in FIG. FIG. 5 shows these landing light generators 320A, 320B, 320C.
Shows the connection. In FIG. 5, there are three light sources A, B, and C. Assuming that the resulting luminance is as shown in FIG. 6, each of the landing light generators 320B, 32B
Each adder 318 in 0C has a function of adding the luminance of the overlapping portions of the illumination lights 60A, 60B, and 60C from different light sources to increase the brightness.

The screen coordinates (X
_The luminance due to the landing light in _S , Y _S , Z _S ) is input to the video signal calculator 302 and added to the luminance of the background.

In the above embodiment, since the luminance pattern is irradiated by one light source, the luminance pattern is circular. When the light is irradiated from a plurality of light sources, the luminance pattern is superposed as shown in FIG. May be changed to an irradiation state by a plurality of light sources, and any one of them may be selected.
In this case, it is necessary to send a code for selecting one to the pattern memory 316 from the digital computer 301 in FIG.

[0062]

As described above, according to the present invention, by dynamically applying the texture stored in the pattern memory on the light plane that moves with the viewpoint, the luminance that dynamically changes for each frame is mapped onto the terrain. Therefore, it is possible to simulate light illumination from a light source that moves with the viewpoint.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure of the present invention.

FIG. 3 is a block diagram of a simulated view generation device used in the present invention.

FIG. 4 is a diagram schematically illustrating a shape of a luminance pattern stored in a pattern memory and a state of the luminance distribution.

FIG. 5 is a diagram in which a plurality of landing light generating devices 320 are connected.

FIG. 6 is a diagram for explaining the operation of an adder 318, and is a diagram for summing the luminances of three light sources A, B, and C;

FIG. 7 is a diagram showing four types of luminance patterns by single and multiple light sources.

FIG. 8 is a diagram illustrating a texture.

FIG. 9 is a diagram schematically illustrating a procedure for converting a normal simulated visual field generation.

FIG. 10 is a diagram schematically illustrating an inverse conversion procedure used in conventional texture mapping.

FIG. 11 is a flowchart illustrating coordinate conversion in conventional texture mapping.

FIG. 12 is a diagram illustrating a conventional example of mapping a texture on the ground.

[Explanation of symbols]

 11 viewpoint 12 light source 13 light plane 14 luminance pattern 15 screen 16 origin of earth coordinate system 17 polygon 301 digital computer 302 video computer 302 320 landing light generator 311a, 311b matrix accumulator 303 Z inverter 313a, 313b multiplier 314a, 314b address generation 315a, 315b Limiter 316 Pattern memory 317 Attenuation table 318 Adder

Claims (1)

(57) [Claims] 1. A simulated visual field generation for displaying a two-dimensional image viewed from a specified viewpoint by attaching a necessary pattern to a polygonal surface constituting a supposed three-dimensional scene stored in a database. In the method, light radiated from a directional light source included in the assumed moving object always exists at a fixed distance from the viewpoint position , and the direction is set to the viewpoint.
The luminance pattern formed when illuminating the light plane that is assumed to move also is stored in the pattern memory in advance, and the position on the screen surface is inversely transformed into the coordinates on the earth assumed by the database viewed from the viewpoint, and A simulated field of view wherein a position when projected from the light plane to the coordinate point on the earth is obtained as an address of the pattern memory, and displayed as light illumination at the coordinate point on the earth from the luminance pattern read from the pattern memory. How it occurs.