JPH07249053A - Projection area calculating method using cad - Google Patents

Abstract

PURPOSE:To provide a projection area calculating method, using CAD, which can calculate the area encircled with a visible outline by automatically generating the visible outline from projected three-dimensional graphic data when the three-dimensional graphic data are projected on a plane. CONSTITUTION:The three-dimensional graphic data to be projected and the projection plane are specified to project the graphic, and the point having maximum X, Y, and Z values and the point having the minimum X, Y, and Z values in an XYZ coordinate system are set from the projected graphic data; and the segment connecting both the points is set, and orthogonal planes which cross the segment at right angles are set between the two points at a specific distance. The intersections of the orthogonal planes and the projected graphic data are found and while the two most distant points among the intersections in the respective orthogonal planes are left, other intersections are erased. Then the graphic data are erased except the selected intersections. The remaining intersections are connected to intersections which are shorter in distance between intersections in adjacent orthogonal planes to generate the visible outline on the projection plane S1-S4. Lastly, the area of the part encircled with the visible outline is found S5.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a CAD (Computer Aid)
ed Design), it relates to a projected area calculation method using CAD when three-dimensional graphic data is projected on a two-dimensional plane.

[0002]

2. Description of the Related Art In recent years, designing by CAD has become widespread. During the CAD design, a process of projecting three-dimensional graphic data on a two-dimensional plane and calculating the area of the projected graphic data may be performed.

For example, in the automobile manufacturing industry, when examining the effective light emitting area of a designed winker in a model of a vehicle body designed as a three-dimensional wireframe model on CAD, the winker is designed to have a predetermined area from a predetermined direction. It is confirmed whether it looks like the above. In that case, the effective light emitting area is confirmed by projecting the three-dimensional wire frame model of the winker on a plane in a predetermined direction and determining the area.

[0004]

[Problems to be Solved by the Invention] However, CAD
When the three-dimensional wireframe model is projected on the two-dimensional projection plane above, many intersecting curves are present on the projection plane, and the outline of the projected figure data is automatically specified. Difficult to do. Therefore, the operator must perform the complicated work of identifying the lines forming the outline and deleting the other lines.

The present invention has been made to solve this type of problem, and when three-dimensional graphic data is projected on a plane, an outline is automatically created from the projected graphic data, C that can calculate the area surrounded by the outline
An object is to provide a projected area calculation method using AD.

[0006]

In order to achieve the above object, the present invention provides a method for calculating a projected area in CAD, in which three-dimensional graphic data is projected on an arbitrary plane to obtain the area of the projected image. A step of specifying three-dimensional graphic data to be projected, a step of setting a projection plane, a step of parallel projecting the three-dimensional figure data from the normal direction of the projection plane to the projection plane, Among the graphic data projected on the plane, the maximum values Xmax, Ymax, Zmax and the minimum values Xmin, Ymin of X, Y, Z respectively in the XYZ coordinate system.
The process of obtaining Zmin and the point (X
max (Ymax, Zmax) and the minimum value (Xmi
n, Ymin, Zmin) and the process of setting a line segment connecting
A process of setting a plurality of orthogonal planes perpendicular to the line segment at predetermined intervals and setting between the two points, and an intersection point between the orthogonal plane and the projected graphic data is obtained, and among the intersection points on each orthogonal plane. , A process of leaving two intersections with the longest distance between them and erasing the other intersections, a process of erasing the projected graphic data excluding the remaining intersections, and the intersections remaining on the orthogonal plane are adjacent to each other. Among the two intersecting points of the orthogonal planes, a step of creating an outline by connecting with an intersection having a shorter distance, and a step of obtaining an area of a portion surrounded by the outline are provided. .

[0007]

In the projected area calculation method using CAD according to the present invention, the three-dimensional graphic data to be projected and the projection plane are specified, and the graphic data is projected from the normal direction of the projection plane onto the projection plane. , Maximum values Xmax, Yma of X, Y, Z respectively in the XYZ coordinate system from the projected graphic data
x, Zmax and minimum values Xmin, Ymin, Zmin are obtained, and a point connecting the two points by setting the point (Xmax, Ymax, Zmax) having the maximum value and the point (Xmin, Ymin, Zmin) having the minimum value. Minutes are set, and orthogonal planes that are orthogonal to the line segments are provided at a predetermined distance from each other. Further, the intersections of the orthogonal planes and the projected graphic data are obtained, and among the intersections in each orthogonal plane, only the two intersections that are most apart from each other are left and the other intersections are erased. This is to create parallel lines that are substantially spaced apart on the projection plane by a predetermined distance,
This means that the intersections between the graphic data projected on the projection plane and the parallel lines are obtained, and only the intersections belonging to the outline line are selected from the intersections.

After selecting only the intersections forming the outline in this way, the graphic data excluding the intersections are erased. A contour line is created on the projection plane by connecting the remaining intersections with the intersections having shorter distances among the intersections of the adjacent orthogonal planes. After that, the area of the part surrounded by the outline is obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection area calculating method using CAD according to the present invention will be described below in detail with reference to the accompanying drawings with reference to preferred embodiments.

In the present embodiment, the CAD device will be described first, then the outline of the method will be described, and finally, the essential parts thereof will be described in detail.

As shown in FIG. 1, the CAD device 10 stores a CPU 12 for graphic processing, an external storage device 14 such as a hard disk for storing graphic data, an internal memory 16, a graphic, numerical values and the like. A CRT display 18 for displaying, a keyboard 20 for inputting numerical values, and an instruction input device 2 for instructing graphic processing such as function keys.
It consists of 2.

A method of calculating the projected area in the CAD device 10 having the above structure will be described below with reference to the flow chart and the drawings.

First, an outline will be described with reference to the flow chart shown in FIG. 2 and FIGS.

The CAD device 10 includes an instruction input device 22.
After starting by the operation of, the projection area calculation program is read from the CPU 12. Then, the three-dimensional graphic data, here the three-dimensional wire frame model, is read from the external storage device 14 into the CPU 12 (step S1). Next, a projection plane P (see FIG. 4) to be projected is designated by an operation input from the keyboard 20 or the instruction input device 22 (step S2). Further, a curve group C1 (see FIG. 4) for obtaining the projected area in the model is designated by an operation input from the keyboard 20 or the instruction input device 22 (step S3). In response to an instruction from the instruction input device 22, the projection plane P
The curve group C1 is parallel-projected from the normal direction to the projection plane P to obtain the outline of the curve group C2 (see FIG. 5) projected on the plane (step S4). The area of the portion surrounded by the outline is obtained and displayed on the CRT display 18 (step S5).

The process of obtaining the outline of step S4 will be described in detail with reference to FIGS.

By operating a key or the like for instructing the calculation of the projected area in the instruction input device 22, as shown in FIG. 4, a group of curves C1 made up of a three-dimensional wire frame model is projected from the normal direction of the projection plane P. Parallel projection is performed on the plane P (step S4-1).

The curve group C2 projected on the projection plane P is shown in FIG. Among the points forming the curve group C2, the maximum values Xmax, Ymax, Zmax, minimum values Xmin, Ymin, Zmi of the X component, the Y component, and the Z component in the XYZ coordinate system, respectively.
n is calculated (step S4-2). Then, as shown in FIG. 5, the point q1 (Xmax, Y
max, Zmax) and a point q2 (Xmin
, Ymin, Zmin), and a line segment h connecting the two points is set (step S4-3). The orthogonal planes P1 to Pn orthogonal to the line segment h are set at a predetermined interval and set between the two points (step S4-4) (see FIG. 6).

In this series of processing, the orthogonal planes P1 to P1
A plurality of Pn are set between the points q1 and q2, but the point q
1 and q2 are maximum values Xmax, Ymax, Zmax, and minimum values X of the X component, Y component, and Z component in the XYZ coordinate system, respectively.
Since it is composed of min, Ymin, and Zmin, the orthogonal planes P1 to Pn are set in a wider range than the curve group C2.

The process of finding the intersection points i of the orthogonal planes P1 to Pn and the group of curves C2, selecting the two points of intersection i which are the farthest apart from each other in the orthogonal planes and erasing the other points is repeated over the orthogonal planes P1 to Pn. Do (Step S4-
5 to S4-7). For example, the orthogonal plane Pm (1 <m <n)
Then, as shown in FIG. 7, the curve c that constitutes the curve group C2
1 to c5 form intersections i1 to i5 with the orthogonal plane Pm, and among the intersections i1 to i5, only i1 and i5 farthest from each other are selected, and the other intersections i2 to i4 are erased. To do. The intersections i1 and i5 selected in this way are defined as Sm1 and Sm2, respectively. This means that only the intersection points that substantially form the outline L are selected.

In this embodiment, the orthogonal planes P1 and Pn are
Then, it is assumed that there is no intersection with the curve group C2.

Further, the curve group C2 is erased, leaving only the intersections Sk1 and Sk2 (2≤k≤n-1) selected on the orthogonal planes P2 to Pn-1 (step S4-8). As a result, a group of intersections Sk1 and Sk2 as shown in FIG. 8 remains. The graphic data of each intersection Sk1 and Sk2 is the orthogonal plane P2.
~ Pn-1 and stored in the memory 16.

Hereinafter, the outlines L are created by connecting the intersections Sk1 and Sk2 (step S4-9) (see FIG. 9). This step S4-9 will be described below with reference to the flowchart shown in FIG. 10 and FIG.

First, the CPU 12 initializes k indicating which orthogonal plane Pk is 1 to 1, and j indicating the start or end of the outline L to 0 (step S4).
-9-1).

Next, the graphic data of the intersections Sk1 and Sk2 related to the orthogonal plane Pk is read from the memory 16 and it is determined whether or not the intersections Sk1 and Sk2 exist in the orthogonal plane Pk (step S4-9-2). ). In the present embodiment, first, the orthogonal plane P1 is determined, and the orthogonal plane P1 is determined.
Since there is no intersection in, the determination is NO, and then j
= 1 is determined (step S4-9-3). Here, the orthogonal plane Pk is the intersection S that constitutes the outline L.
It is determined whether or not it is an orthogonal plane without the next intersection of the orthogonal plane Pk-1 having k-11 and Sk-12. Since the orthogonal plane P1 is j = 0 ≠ 1, that is, NO, k
Is incremented (step S4-9-4) and the processing from step S4-9-2 is repeated.

Then, k = 2, that is, the orthogonal plane P2
Since there are intersections S21 and S22 in step S4, step S4
It becomes YES in -9-2, and it is determined whether or not j = 0 (step S4-9-5). Here, it is determined whether or not it is the first orthogonal plane Pk having the intersections Sk1 and Sk2 that form the outline L. The orthogonal plane P2 is
Since it is the first plane (J = 0), the intersection S21 and the intersection S2
2 are connected (step S4-9-6) (see the solid line in FIG. 8). After that, k and j are respectively incremented (step S4-9-7), and the processing from step S4-9-2 onward is repeated.

Intersection points S31 and S32 are present on the orthogonal plane P3 (step S4-9-2), and it is not the first plane forming the outline (j = 1 ≠ 0) (step S4-9-).
5) Therefore, the intersections S31 and S32 are connected to the intersections S21 and S22 of the orthogonal plane P2 that has been processed immediately before and the intersections having shorter distances, respectively (step S4-9-8). That is, the intersection S21 and the intersection S31, and the intersection 22 and the intersection 32 are connected (see the broken line in FIG. 8).

Hereinafter, until k becomes n, k is incremented and the processing from step S4-9-2 is repeated (steps S4-9-9 and S4-9-10).

If the intersection points Sn1 and Sn are reached up to the orthogonal plane Pn,
If 2 exists, the intersection Sn1 and the intersection Sn2 are connected to complete the creation of the outline L (step S4-9-1).
1).

In this embodiment, since there are intersections on each orthogonal plane up to the orthogonal plane Pn-1, the intersections are connected to each other. However, since there is no intersection on the orthogonal plane Pn, the process proceeds to step S4-9-3, and it is determined whether J = 1. J = 1, that is, the orthogonal plane Pn-1 having the intersection points Sn-11 and Sn-12 that form the outline L
Since it is the first orthogonal plane Pn without the next intersection of
As shown by the chain double-dashed line, the intersection points Sn-11 and Sn-12 on the orthogonal plane Pn-1 processed one before are connected to complete the creation of the outline L (see FIG. 9) (step S4-
9-12).

The area of the portion surrounded by the outline L thus obtained is calculated. Hereinafter, description will be given with reference to FIGS. 11 to 14.

First, as shown in FIG. 11, a coordinate system U-V is set on the projection plane P, and the average value Vm = (Vmax +) from Vmax and Vmin in the area surrounded by the outline L.
Vmin) / 2 is calculated. Then, a straight line of V = Vm is drawn, and the intersection points T1 and T2 of the straight line and the outline L are obtained.

Next, the value U of U at the intersection points T1 and T2,
The average value Um = (U1 + U2) / 2 is calculated from U2,
As shown in 2, the center C (Um, Vm) is set.

Further, as shown in FIG. 13, a straight line M passing through the center C on the projection plane P is set at a predetermined angle, for example, 1
° Pull at intervals.

Finally, the intersection T of the straight line M and the outline L
Of the intersections Tk-1, Tk and the center C
The area of the triangle formed by is calculated (see FIG. 14). The areas of all the triangles are calculated, and the sum of them is calculated to calculate the area of the region surrounded by the outline L, and the area is displayed on the CRT display 18.

In the projected area calculation method using CAD according to this embodiment, the curve group C which is the three-dimensional figure data to be projected is used.
1 and the projection plane P are specified, and the projection area is calculated by the CAD device 1
If 0 is specified, the contour line L of the curve group C2 that is automatically projected is created, and the area of the portion surrounded by the contour line L is automatically calculated. Therefore, if the operator
It becomes unnecessary to specify the outline L of No. 2 and the work efficiency is improved.

Further, in this method, the projected curve group C2
The contour line L is obtained from the intersection i of the orthogonal planes P1 to Pn and the orthogonal planes P1 to Pn are XYZ of the curve group C2.
Since it is set between the points q1 and q2 having the maximum and minimum values of X, Y, and Z in the coordinate system, the orthogonal planes P1 to Pn are wider than the both ends of the curve group C2.
Is set. As a result, all the intersections i that form the outline L are detected, and the outline L is created with high accuracy.

[0037]

According to the projected area calculation method using CAD according to the present invention, the following effects can be obtained.

That is, in this method, if the three-dimensional graphic data to be projected on the CAD device and the projection plane are specified and the calculation of the projected area is instructed, the outline of the projected graphic data is automatically created. , The projected area is calculated. Therefore, it is possible to obtain an effect that work efficiency is improved because it is freed from a complicated work such as an operator specifying the outline of the projected three-dimensional graphic data.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a CAD device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a projected area calculation method in an embodiment according to the present invention.

FIG. 3 is a flowchart showing a main part of a projected area calculating method according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a contour line creating method of a projected curve group in the projected area calculating method according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a contour line creating method of a projected curve group in the projected area calculating method according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a method of creating an outline of a projected curve group in a projected area calculation method according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a method of creating an outline of a projected curve group in the projected area calculation method according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a contour line creating method of a projected curve group in the projected area calculating method according to the embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a method of creating an outline of a projected curve group in the projected area calculation method according to the embodiment of the present invention.

FIG. 10 is a flowchart showing a contour line creating method in the projected area calculating method according to the embodiment of the present invention.

FIG. 11 is an explanatory diagram showing an area calculating method in the projected area calculating method according to the embodiment of the present invention.

FIG. 12 is an explanatory diagram showing an area calculating method in the projected area calculating method according to the embodiment of the present invention.

FIG. 13 is an explanatory diagram showing an area calculating method in the projected area calculating method according to the embodiment of the present invention.

FIG. 14 is an explanatory diagram showing an area calculating method in the projected area calculating method according to the embodiment of the present invention.

[Explanation of symbols]

10 ... CAD device 12 ... CPU 14 ... External storage device 16 ... Memory 18 ... CRT display 20 ... Keyboard 22 ... Instruction input device C1, C2 ... Curve group L ... Outline line P ... Projection plane

Claims (1)

[Claims] 1. A method for calculating a projected area in CAD, in which three-dimensional graphic data is projected onto an arbitrary plane to obtain the area of a projected image, the method comprising: specifying three-dimensional graphic data to be projected; A step of setting a plane; a step of projecting the three-dimensional figure data in parallel from the normal direction of the projection plane onto the projection plane; and a figure data projected on the projection plane in which X, Y in an XYZ coordinate system. , Z respectively maximum values Xmax, Ymax, Zma
The process of obtaining x and the minimum values Xmin, Ymin, Zmin, and the point (Xmax, Ymax, Zmax) composed of the maximum values
And a step of setting a line segment connecting a point (Xmin, Ymin, Zmin) constituted by the minimum value, and a step of setting a plurality of orthogonal planes perpendicular to the line segment at predetermined intervals to set between the two points. And obtain the intersection of the orthogonal plane and the projected graphic data,
Among the intersections on each orthogonal plane, leaving two intersections with the longest distance between them, erasing the other intersections, and erasing the projected graphic data except the remaining intersections. , The process of creating the outline by connecting the intersection remaining on the orthogonal plane to the intersection with the shorter distance of the two intersections of the adjacent orthogonal planes, and the process of obtaining the area surrounded by the outline And a projected area calculation method using CAD.