JPH07200874A - Production of two-dimensional drawing for three-dimensional cad system - Google Patents

Abstract

PURPOSE:To improve the quality and to facilitate the maintenance of a two-dimensional drawing and also to effectively use this drawing by converting the vector data on a three-dimensional model into the visual point coordinate data on an optional position from the basic coordinate data and then into the two-dimensional vector data in order to obtain the two-dimensional vector data on the three-dimensional model viewed from an optional position. CONSTITUTION:This system includes e CAD processing part 2 consisting of e CPU, the prescribed software, etc. The CAD processing part 2 includes a scroll bar display control pert 11 which displays a scroll bar to designate the position of a visual point set to three-dimensional model and carries out the processing based on the displayed scroll bar, a visual point coordinate calculating part 12 which calculates the three- dimensional coordinate value of the visual point coordinate system of the three- dimensional model based on the designated visual point position, a screen coordinate converting part 13 which converts the three-dimensional coordinate value of the visual point coordinate system into the screen coordinates, and a two-dimensional CAD data converting part 14 which converts the three-dimensional coordinate value of the visual point coordinate system into the two-dimensional CAD data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of creating a two-dimensional drawing in a three-dimensional CAD system for creating two-dimensional vector data from a three-dimensional model created in a three-dimensional CAD system or the like.

[0002]

2. Description of the Related Art Conventionally, when a three-dimensional drawing created by a three-dimensional CAD system is displayed as an image from an arbitrary viewpoint position and the two-dimensional image is output, the bit map data as display data is hard-copyed as it is. It is made to output as.

[0003]

However, in such a method, since the generated two-dimensional image is composed of bitmap data, there is a problem that the print quality is poor and maintenance and reuse are not easy. Also, 3
A system for creating a necessary three-view drawing or the like from a dimensional model is also known, but the directions that can be created are limited to each axial direction of the basic coordinate system, and a two-dimensional drawing cannot be obtained from any direction.

The present invention has been made in order to solve such a problem, and is a method of creating a two-dimensional drawing in a three-dimensional CAD system capable of creating a two-dimensional drawing viewed from an arbitrary position of a three-dimensional model. The purpose is to provide a creation method.

[0005]

Three-dimensional CA according to the present invention
The method of creating a two-dimensional drawing in the D system is defined by three-dimensional vector data in the basic coordinate system.
A step of converting the three-dimensional model into three-dimensional vector data of a viewpoint coordinate system at a designated position; a step of converting the three-dimensional vector data converted in this step into two-dimensional vector data; Storing dimension vector data.

[0006]

According to the present invention, the vector data of the three-dimensional model is converted from the basic coordinate system into the data of the viewpoint coordinate system at an arbitrary position, and further converted into the two-dimensional vector data so that the data can be seen from an arbitrary position. Two-dimensional vector data of a three-dimensional model can be created. Since the obtained two-dimensional drawing is vector data, output quality is good, maintenance is easy, and effective use can be achieved. In addition,
If the created 2D vector data is linked to the original 3D vector data and the 2D vector data is also modified as the 3D vector data is modified, the maintainability is further improved. To do.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a functional block diagram showing the configuration of a three-dimensional CAD system according to an embodiment of the present invention.
This system includes an input unit 1 such as a mouse and a keyboard,
A CAD processing unit 2 including a CPU and predetermined software, a two-dimensional drawing data storage unit 3 and a three-dimensional drawing data storage unit 4 such as an external disk device, a display unit 5 such as a CRT display device, a printer, A print output unit 6 such as a raster plotter is provided.

The CAD processing unit 2 displays the scroll bar for designating the position of the viewpoint with respect to the three-dimensional model and the scroll bar display control unit 1 for executing processing based on the display.
1, a viewpoint coordinate calculation unit 12 that calculates a three-dimensional coordinate value in the viewpoint coordinate system of the three-dimensional model based on the designated viewpoint position, and a screen coordinate conversion that converts the three-dimensional coordinate value in the viewpoint coordinate system into screen coordinates. A unit 13 and a two-dimensional CAD data conversion unit 14 that converts three-dimensional coordinate values in the viewpoint coordinate system into two-dimensional CAD data are provided.

Next, the operation of the present system thus constructed will be described. FIG. 2 is a diagram showing an example of a scroll bar used in this system. Display area 2 of three-dimensional model 21 formed on the display screen of display unit 5
The first scroll bar 23 is displayed in the upper frame portion of 2, and the second scroll bar 23 is displayed in the left frame portion of the display area 22.
The scroll bar 24 of is displayed. These scroll bars 23 and 24 are each provided with a scale of -180 ° to 180 °, and the first pad 25 is within that range.
Also, the second pad 26 moves so as to follow the cursor 27 of the mouse.

When the first pad 25 is moved in the horizontal direction, as shown in FIG. 3A, the basic coordinate system X, Y, Z of the three-dimensional model 21 is centered on the origin O of the basic coordinate system X, Y, Z.
The viewpoint position along the horizontal plane of Y and Z, that is, the viewpoint coordinate system X
e, Ye, and Ze (however, Ze is the line-of-sight direction vector) move rotationally. When the second pad 26 is moved in the vertical direction, as shown in FIG. 3B, the basic coordinate system X, Y, Z centering on the origin O of the basic coordinate system X, Y, Z of the three-dimensional model 21.
The viewpoint coordinate systems Xe, Ye, and Ze rotate and move along the vertical planes of Y and Z. Thereby, the viewpoint coordinate system Xe, Ye, Z
e can move to all positions on a sphere centered on the origin O of the basic coordinate system X, Y, Z.

In addition to this, in this embodiment, a third pad 28 is also displayed at the intersection of the first and second scroll bars 23 and 24 shown in FIG. 2, and the mouse cursor is positioned on this pad. When the dragging operation is performed by the dragging operation, the first and second pads 25 and 26 are simultaneously moved according to the dragging direction.

In this case, when the cursor 27 is moved in the upper left direction or the lower right direction, the first and second pads 25, 2
6 moves in the direction of decreasing or increasing together, as shown in FIG.
As shown in, the viewpoint coordinate systems Xe, Ye, and Ze move along the left upward surface of the basic coordinate systems X, Y, and Z. Also,
If you move the cursor 27 to the lower left or upper right,
One of the first and second pads 25, 26 decreases,
The other moves in the increasing direction, and as shown in FIG. 4B, the viewpoint coordinate system Xe, Ye, Ze is changed to the basic coordinate system X, Y,
Move along the upward-sloping surface of Z.

Next, the above processing and the processing for generating two-dimensional CAD data from a three-dimensional model viewed from an arbitrary viewpoint position by this processing will be described with reference to the flowchart of FIG. The change of the display attitude of the three-dimensional model is realized by executing the following display coordinate calculation processing every time the movement of the cursor is detected (S1). First, the pads 2 of the scroll bars 23 and 24 are based on the cursor position of the mouse.
The display positions of 5 and 26 are moved (S2). From the display positions of the pads 25 and 26 of the scroll bars 23 and 24, FIG.
As shown in, the angle θh on the horizontal plane of the origin P of the viewpoint coordinate system
And the angle θv on the vertical plane are uniquely obtained (S
3).

Next, the viewpoint coordinate system is obtained from the angles θh and θv (S4). As shown in FIG. 6, the viewpoint coordinate system is a vector R from the origin P of the viewpoint coordinate system to the origin O of the basic coordinate system.
And unit vectors Xe, Ye, Ze of each axis of the viewpoint coordinate system
And are also uniquely obtained from the angles θh and θv.

Then, the coordinate values of the wire frame of the three-dimensional model 21 defined in the basic coordinate system are converted into coordinate values in the viewpoint coordinate system (S5). That is, if the direction cosine matrix of the unit vectors X, Y, Z of the axes of the basic coordinate system and the unit vectors Xe, Ye, Ze of the axes of the viewpoint coordinate system is T, then the basic coordinate system of the three-dimensional model 21. Coordinate value x at,
The coordinate values xe, ye, and ze after conversion from y and z are obtained by the following mathematical expression 1.

[0016]

## EQU1 ## [xye ze] = [xyz] T + [rx ry rz] where rx, ry, and rz are scalars, and R = rx Xe + ry Ye + rz Ze

Next, in order to obtain a projection drawing from the three-dimensional model in the obtained viewpoint coordinate system onto the two-dimensional plane, the coordinate values of the viewpoint coordinate system are converted into the coordinate values of the screen coordinate system (S).
6). As this processing, a projection method, a parallel method and the like are known, but in the case of the projection method, it is necessary to further specify the projection angle.

In the case of the projection method, if the position of the screen 30 standing on the line of sight is d and the half width of the screen 30 is s, as shown in FIG. 7, conversion processing is performed as shown in the following equation 2. , Coordinate values xs, ys, zs in the screen coordinate system are obtained. In addition, w is a scale factor, and xs = x /
w, ys = y / w, zs = z / w.

[0019]

[2] [x yz w] = [x ye ze 1] P

When conversion is performed by the parallel method, d
= ∞ The converted coordinate value also includes the coordinate value zs in the line-of-sight direction (depth direction).
Hidden lines / hidden surfaces are erased by determining the magnitude of the coordinate value zs (S7). Thereby, the wire frame information in the two-dimensional space can be obtained. Then, based on the obtained information, the expansion processing to the bit map memory is executed (S8), and the information is displayed on the display unit 5.

The above operation is executed every time the movement of the cursor is detected (S1). Thereby, the three-dimensional model 21 can be rotationally moved in real time on the display screen. When it is confirmed that the three-dimensional model 21 is displayed from the desired direction, a confirmation command is input (S9).

Next, a conversion process into a two-dimensional drawing will be described. When the image of the three-dimensional model viewed from an arbitrary line-of-sight position is displayed on the display unit 5 by the above-mentioned procedure and at the same time the conversion process to the two-dimensional drawing is designated (S10), the above-mentioned hidden line / hidden surface process (S7) is performed. ) A two-dimensional CAD drawing is generated from the subsequent data (S11), stored in the two-dimensional drawing storage unit 3 (S12), and the converted two-dimensional drawing is output through the print output unit 6 as necessary. . That is, since each element data of the wire frame after the hidden line / hidden surface processing is composed of the element type, the two-dimensional coordinate values of x and y, and the necessary parameters, this data is directly used as the two-dimensional C
It can be used as AD data.

A procedure for creating a three-view drawing from the three-dimensional model 21 using this processing will be described with reference to FIGS. The first pad 25 of the three-dimensional model 21 shown in FIG. 8A is moved to the left with the cursor 27 to display the image viewed from diagonally above the front shown in FIG. 8 with the cursor 27 and move it upward.
The image viewed from above as shown in (c) is displayed. Then, after converting this into a two-dimensional drawing to obtain a top view, necessary dimension lines and comments are added.

The same operation is performed as shown in FIGS. 9 and 10 to create a front view and a left side view of the three-dimensional model 21. This makes it possible to easily create a three-view drawing from the three-dimensional model 21. When creating such a three-view drawing, it is convenient to perform two-dimensional conversion by the parallel method.

2 of a perspective view of a three-dimensional model from an arbitrary direction
When outputting a three-dimensional copy, the projection method is preferable because it gives a sense of perspective. In this case, unlike the conventional hard copy output, since the two-dimensional data is vector data, the quality of the print output is good.

The generated information about the two-dimensional drawing is linked to the original three-dimensional drawing and saved, and the conversion parameters such as the direction cosine vector matrix T and the vector R are stored in the three-dimensional drawing. It is preferable to keep. And when the 3D model is modified,
If the coordinate conversion process (S5, S6, S7) described above is executed again inside the system, the correction result of the three-dimensional drawing can be reflected in the two-dimensional drawing.
The two-dimensionally converted data includes many free curves, but by expressing these as free curves instead of as a set of straight lines, the amount of data does not increase and the operability is improved. Also, what can be represented by a circle, an ellipse, etc. may be represented by a circle, an ellipse, etc. instead of a free curve.

[0027]

As described above, according to the present invention, 3
2D vector data of a 3D model viewed from an arbitrary position is created by converting the vector data of the 3D model from the basic coordinate system to the data of the viewpoint coordinate system at an arbitrary position and further converting it to 2D vector data. Since the obtained two-dimensional drawing is vector data, the output quality is good, the maintenance is easy, and the effective use can be achieved.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a three-dimensional CAD system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a scroll bar used in the system.

FIG. 3 is a diagram for explaining a moving direction of a viewpoint position by operating a first pad and a second pad of the scroll bar.

FIG. 4 is a diagram for explaining a moving direction of a viewpoint position by operating the third pad.

FIG. 5 is a flowchart showing a viewpoint position movement process and a two-dimensional drawing data conversion process of the three-dimensional model in the system.

FIG. 6 is a diagram showing a relationship between the basic coordinate system and a viewpoint coordinate system.

FIG. 7 is a diagram for explaining the same screen conversion method.

FIG. 8 is a diagram for explaining an operation procedure for creating a top view from the same three-dimensional model.

FIG. 9 is a diagram for explaining an operation procedure for creating a front view from the same three-dimensional model.

FIG. 10 is a diagram for explaining an operation procedure for creating a right side view from the same three-dimensional model.

[Explanation of symbols]

1 ... Input unit, 2 ... CAD processing unit, 3 ... Two-dimensional drawing data storage unit, 4 ... Three-dimensional drawing data storage unit, 5 ... Display unit, 6
... print output unit, 11 ... scroll bar display control unit, 12
... viewpoint coordinate calculation unit, 13 ... screen coordinate conversion unit, 14
2D CAD data conversion unit, 21 3D model, 2
2 ... Display area, 23 ... First scroll bar, 24 ...
Second scroll bar, 25 ... First pad, 26 ... Second pad, 27 ... Cursor, 28 ... Third pad.

Claims (2)

[Claims] 1. A step of converting a three-dimensional model defined by three-dimensional vector data in a basic coordinate system into three-dimensional vector data of a viewpoint coordinate system at a specified position, and three-dimensional vector data converted in this step. To a two-dimensional vector data, and a step of storing the two-dimensional vector data obtained in this step, a method of creating a two-dimensional drawing in a three-dimensional CAD system. 2. The two-dimensional vector data is stored by linking with the three-dimensional vector data in the basic coordinate system, and when the three-dimensional vector data in the basic coordinate system is changed, the two-dimensional vector data is tracked accordingly. The three-dimensional CAD according to claim 1, wherein the vector data is modified.
A method for creating a two-dimensional drawing in the system.