JPH05165921A - Three-dimensional viewpoint setting method for cad system - Google Patents

Abstract

PURPOSE:To easily set an arbitrary viewpoint at high speed. CONSTITUTION:Concerning the three-dimensional viewpoint setting method for a CAD system, a viewpoint A on a display screen is expressed by using a zenithal angle theta1 of a spherical coordinate with an object on the screen as a central coordinate, azimuth angle theta2 and inclined angle theta3, the respective obtained angles theta1, theta2 and theta3 are converted into parameters vpn and vup for inputting to a standard graphic software by a converter 13 to execute the arithmetic of a rectangular function, these parameters are inputted to the standard graphic software as vector values, and a change into the arbitrary viewpoint is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional viewpoint setting method in a CAD system, and more particularly, a three-dimensional viewpoint capable of displaying an image three-dimensionally displayed on the screen of the CAD system by arbitrarily changing the viewpoint. Regarding the setting method. In recent years, Computer Aided Design: C
AD) system is widely used. This aims to make the design of building structures, arrangement of mechanical parts, wiring patterns, etc. as efficient and highly reliable as possible by utilizing computer graphic (CG) technology.

In the use of such a CAD system, an assembled structure such as a camera is often three-dimensionally displayed from a predetermined viewpoint on the screen of the system in a perspective manner. In this case, it is also necessary to display the composition with a different viewpoint from the viewpoint of design.

[0003]

2. Description of the Related Art Conventionally, as a method of defining a viewpoint for displaying an object, a view plane for the object is defined from the view point. In order to define this view plane, a vector for the view point and a vector orthogonal thereto The values of the two vectors are determined and input to the graphic software.

FIG. 9 is an explanatory diagram of a conventional method. In the figure, 1a and 1b are viewpoints of the operator, 2a and 2b are view planes of the respective viewpoints, and 3 is an object on the display screen. As shown in the figure, as a method of defining a viewpoint with graphic software, conventionally, two three-dimensional vectors vpn,
The view planes 2a and 2b are defined by vup. That is, the vector vpn for the viewpoint 1a is obtained, and the view plane 2a for the object 3 is defined by the vector vup orthogonal to this. The same applies to the viewpoint 1b, and the vector vp
A view plane 2b for the object 3 is defined by n and a vector vup orthogonal to this. Obviously, the vector vpn changes as the viewpoint changes, but
An arbitrary viewpoint is determined by changing the values of the two vectors vpn and vup. Then, the vector value thus obtained is changed to an arbitrary viewpoint by inputting it to the graphic software.

The above is a brief description, but more details are as follows. That is, in terms of the coordinate system for displaying on the screen, the coordinate system of what is displayed, and the relationship between these coordinate systems and the three-dimensional vectors vpn, vup, first, the viewpoint at which the object 3 is viewed is determined. When deciding the viewpoint, give a temporary center in the object, find the sphere centered on that point,
One point on the sphere corresponds to the viewpoint. Next, a plane (view planes 2a, 2b) passing through this viewpoint and contacting the sphere is given, and an image obtained by projecting the object 3 on this view plane is displayed on the screen. Here, the three-dimensional vectors vup and vpn are unit vectors represented by world coordinates (x, y, z), the vector vup is a vector along the view plane, and the vector vpn is on the view plane as shown in the figure. On the other hand, it is a vector in the vertical direction and represents the line of sight.

[0006]

In such a change of viewpoint, the object to be displayed passes wire elements such as its line segment and the data of its surface to the graphic software as parameters. Conventionally, standard software called PHIGS is used as graphic software, or machine-dependent graphic software is used.
The parameters matching the input to the graphic software are extracted from the graphic data and passed to the graphic software.

However, it takes a very long time to determine two vector values each time by the above-mentioned method for setting an arbitrary viewpoint, and there is a practical problem in accelerating the structural design, for example. .. Therefore, when changing to an arbitrary viewpoint, it is not possible to quickly obtain an arbitrary viewpoint by the conventional input to graphic software using two vector values.

An object of the present invention is to provide the above-mentioned conventional graphic display in the three-dimensional display of the CAD system.
It is an object of the present invention to provide a three-dimensional viewpoint setting method in which the view plane can be easily determined without changing software as much as possible, and thus any viewpoint can be set easily and at high speed.

[0009]

FIG. 1 is a diagram illustrating the principle of the present invention, and FIG. 2 is a basic configuration diagram of the present invention. As shown in FIG. 1, in the present invention, the viewpoint A is defined by the zenith angle θ1 in spherical coordinates,
It is determined using the azimuth angle θ2 and the inclination angle θ3. Then, as shown in FIG. 2, the respective angles (θ1, θ
2, θ3) is converted into a parameter (vpn, vup) for input to the standard graphic software by the conversion device 13, and this parameter is used as an input to the graphic software as a vector value.

[0010]

According to the present invention, an arbitrary viewpoint is represented by three angles of spherical coordinates, and this is converted into an input parameter to graphic software, thereby facilitating setting of an arbitrary three-dimensional viewpoint in a CAD system. It can be carried out.

[0011]

[Example] In FIG. 2, a screen 11a of a CAD system
The structure 12a viewed from a predetermined viewpoint is displayed above. Further, the structure 12b viewed from the changed viewpoint is displayed on the screen 11b. In the present invention, the conversion device 13 for changing the viewpoint as shown in the screen 11b is provided. First, the three-dimensional viewpoint A for graphically displaying the structure 11a currently displayed is set to the zenith angle θ1 and the azimuth angle θ.
2. Set with inclination angle θ3. Then, these angles are input to the conversion device 13, a predetermined calculation described later is performed, the vector values vpn and vup are obtained, and the system is notified, and the viewpoint of the screen 11b is obtained. The conversion device 13 is, for example, a calculation device that performs a calculation of a triangular function as described below.

FIG. 3 is a diagram for specifically explaining the spherical coordinates of the present invention. A point O in the figure is the center of the object, and a point P is a point on the spherical surface between the center O and the viewpoint A. Here, θ1 is a zenith angle indicating an angle from the z axis, θ2 is an azimuth angle indicating an angle from the x axis, and θ3 is an inclination angle indicating an inclination of the viewing plane PL. The inclination of the inclination angle θ3 represents the inclination of the object. Therefore, such three parameters (θ1, θ
2, θ3) can represent an arbitrary viewpoint. θ1, θ2, and θ3 are in the range of 0 ° to 360 °.

FIG. 4 is a concrete explanatory view of the coordinate calculation of the present invention. The center point O of the object is the center of the xyz axes. The normal vector at the point P on the plane PL is vpn, and the xyz component of this vector vpn is defined. That is, first, the vector vpn is decomposed into the z direction and the direction parallel to the xy plane. xy plane → sin θ1 ... (1) z component → cos θ1 ... (2) Formula (1) is further decomposed into x component and y component.

X component → sin θ1 · cos θ2 ... (3) y component → sin θ1 · sin θ2 ・ ・ ・ ・ (4) From equations (2) to (4), vpn = (sin θ1 · cos θ2 , Sin θ1 ・ sin θ2
cos θ1) ... (5) FIGS. 5 to 8 are more specific explanatory diagrams of the coordinate calculation of the present invention. As shown, the direction vector vu on the view plane
Define the xyz component of p.

First, as shown in FIG. 5, the vector vup
Is the direction of θ3 = 0 (that is, the direction of the vector vup), and
It decomposes in the direction parallel to the xy plane. vup (θ3 = 0) → cos θ3 ... (6) xy plane → sin θ3 ... (7) Next, as shown in FIG. 6, the equation (6) is further converted into the z-axis direction and the xy plane. Disassemble in a direction parallel to.

Z component → cos θ3 · sin θ1 (8) xy plane → cos θ3 · cos θ1 ... (9) Next, as shown in FIG. x component and y
Decomposes into components. x component → cos (θ2 + π) ・ cos θ3 ・ cos θ1 = −cos θ2 ・ cos θ3 ・ cos θ1 ・ ・ ・ ・ (10) y component → sin (θ2 + π) ・ cos θ3 ・ cos θ1 = −sin θ2 ・ cos θ3 .Cos .theta.1 ... (11) Next, as shown in FIG.
Decomposes into components.

X component → cos (θ2 + π / 2) · sin θ3 = −sin θ2 · sin θ3 ... (12) y component → sin (θ2 + π / 2) · sin θ3 = cos θ2 · sin θ3 ... (13) Next, according to equations (6) to (13), vup = (-cos θ2 · cos θ3 · cos θ1-sin θ2
・ Sin θ3, −sin θ2 ・ cos θ3 ・ cos θ1 + cos θ
2 · sin θ3, cos θ3 · cos θ1)
(14) Finally, the conversion device 13 converts the equations (5) and (10) to obtain the zenith angle θ1, the azimuth angle θ2, and the inclination angle θ3.
Can be transformed into vectors vpn and vup.

[0018]

As described above, according to the present invention,
In the three-dimensional display of the CAD system, the viewpoint is determined by the zenith angle, the azimuth angle, and the inclination angle, and by converting these into the conventional vector, the display screen of the CAD system can be easily changed to an arbitrary viewpoint. It is possible to speed up the design using the CAD system.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a basic configuration diagram of the present invention.

FIG. 3 is a specific explanatory diagram of spherical coordinates of the present invention.

FIG. 4 is a specific explanatory view of coordinate calculation according to the present invention.

FIG. 5 is a more specific explanatory diagram of coordinate calculation according to the present invention (No. 1).

FIG. 6 is a more specific explanatory diagram of the coordinate calculation according to the present invention (No. 2).

FIG. 7 is a more specific explanatory diagram of coordinate calculation according to the present invention (No. 3).

FIG. 8 is a more specific explanatory diagram of coordinate calculation according to the present invention (No. 4).

FIG. 9 is an explanatory diagram of a conventional method.

[Explanation of symbols]

 11a, 11b ... CAD screen 12a, 12b ... Display screen 13 ... Conversion device

Claims (2)

[Claims] 1. A three-dimensional viewpoint setting method in a CAD system, wherein a viewpoint (A) on a display screen is a zenith angle (θ1) and an azimuth angle (θ2) of spherical coordinates having an object on the screen as a center coordinate. And the inclination angle (θ3), and the obtained angles (θ1, θ2, θ3) are converted into parameters (vpn, vup) for input to the standard graphic software by the conversion device 13. A three-dimensional viewpoint setting method in a CAD system, characterized in that these parameters are input as vector values to the standard graphic software to change the viewpoint. 2. The three-dimensional viewpoint setting method according to claim 1, wherein the conversion device is an arithmetic device of a triangular function.