JP3414478B2 - Projection area calculation method using CAD - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CAD (Computer Aid)
ed Design), a projection area calculation method using CAD when three-dimensional graphic data is projected onto a two-dimensional plane. 2. Description of the Related Art In recent years, designing by CAD has become widespread. During the CAD design, a process of projecting the three-dimensional graphic data onto 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 blinker in a vehicle body model designed as a three-dimensional wire frame model on CAD, the blinker has a predetermined area from a predetermined direction. I'm checking if it looks like this. In this case, the three-dimensional wire frame model of the blinker is projected on a plane in a predetermined direction, and the area of the three-dimensional wire frame model is obtained to confirm the effective light emitting area. [0004] However, CAD
When the three-dimensional wireframe model is projected on the two-dimensional projection plane above, many intersecting curves exist on the projection plane, and the outline of the projected graphic data is automatically specified. Difficult to do. Therefore, the operator has to perform a complicated operation of specifying the lines constituting the outline and erasing the other lines. The present invention has been made to solve this kind of problem. When three-dimensional graphic data is projected onto a plane, an outline is automatically created from the projected graphic data. C that can calculate the area surrounded by the outline
It is an object to provide a projection area calculation method using AD. SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a CAD system which projects three-dimensional graphic data onto an arbitrary plane in CAD to obtain an area of a projected image. An area calculating method, wherein a step of specifying three-dimensional graphic data to be projected, a step of setting a projection plane, and a step of parallel projecting the three-dimensional graphic data from the normal direction of the projection plane to the projection plane. , In the graphic data projected on the projection plane, the maximum values Xmax, Ymax, Zmax and the minimum values Xmin, Ymin,
Zmin and a point (X
max, Ymax, Zmax) and a point (Xmi
n, Ymin, Zmin); and
A step of setting a plurality of orthogonal planes perpendicular to the line segment between the two points by separating them by a predetermined distance, and finding an intersection between the orthogonal plane and the projected graphic data; Leaving the two intersections with the longest separation distance therebetween and erasing the other intersections; erasing the projected graphic data excluding the remaining intersections; and intersecting the intersections remaining on the orthogonal plane with each other. A process of creating an outline by connecting to an intersection having a shorter distance between two intersections of the orthogonal plane, and a process of obtaining an area of a portion surrounded by the outline. . In the projection area calculation method using CAD according to the present invention, the three-dimensional figure data to be projected and the projection plane are specified, and the figure data is converted from the normal direction of the projection plane to the projection plane. And the maximum values Xmax, Yma of X, Y, Z in the XYZ coordinate system from the projected graphic data.
x, Zmax and minimum values Xmin, Ymin, Zmin are determined, a point (Xmax, Ymax, Zmax) consisting of the maximum value and a point (Xmin, Ymin, Zmin) consisting of the minimum value are set, and a line connecting both points is set. An interval is set, and an orthogonal plane orthogonal to the line segment is provided between two points at a predetermined interval. Further, an intersection between the orthogonal plane and the projected graphic data is obtained, and only two of the intersections in each orthogonal plane that are most separated from each other are left, and other intersections are deleted. This creates parallel lines substantially spaced apart by a predetermined distance on the projection plane,
The intersection between the graphic data projected on the projection plane and the parallel line is obtained, and only the intersection belonging to the outline is selected from the intersections. After selecting only the intersections forming the outline in this way, the graphic data excluding the intersections is deleted. The remaining intersection is connected to the intersection of the shorter distance among the intersections of the adjacent orthogonal planes, so that an outline is created on the projection plane. Thereafter, the area of the portion surrounded by the outline is determined. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection area calculation method using a CAD according to the present invention will be described in detail below with reference to the accompanying drawings. In this embodiment, a CAD apparatus will be described first, then an outline of the method will be described, and finally the main part will be described in detail. As shown in FIG. 1, the CAD apparatus 10 includes a CPU 12 for performing graphic processing, an external storage device 14 such as a hard disk for storing graphic data, an internal memory 16, a graphic and numerical values. CRT display 18 for displaying, keyboard 20 for inputting numerical values, and instruction input device 2 for instructing graphic processing such as function keys
Consists of two. A method of calculating a projected area in the CAD apparatus 10 having the above-described configuration will be described below with reference to flowcharts and drawings. First, the outline will be described with reference to the flowchart shown in FIG. 2 and FIGS. 4 and 5. The CAD device 10 includes an instruction input device 22
After the start-up operation, the CPU 12 reads the projection area calculation program from the CPU 12. Subsequently, three-dimensional graphic data, here, a three-dimensional wireframe 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 a projection area is designated in the model by an operation input from the keyboard 20 or the instruction input device 22 (step S3). The projection plane P is designated by an instruction from the instruction input device 22.
From the normal direction, the curve group C1 is projected in parallel to the projection plane P, and the outline of the curve group C2 (see FIG. 5) projected on the plane is obtained (step S4). The area of the portion surrounded by the outline is determined and displayed on the CRT display 18 (step S5). The process of obtaining the outline in step S4 will be described in detail with reference to FIGS. By operating a key or the like for instructing projection area calculation in the instruction input device 22, a curve group C1 composed of a three-dimensional wire frame model is projected from the normal direction of the projection plane P as shown in FIG. Parallel projection is performed on the plane P (step S4-1). FIG. 5 shows a curve group C2 projected on the projection plane P. Among the points constituting the curve group C2, the maximum values Xmax, Ymax, Zmax and the minimum values Xmin, Ymin, Zmi of the X, Y, and Z components in the XYZ coordinate system, respectively.
n is obtained (step S4-2). Subsequently, as shown in FIG. 5, a 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). Orthogonal planes P1 to Pn orthogonal to the line segment h are set to be separated from each other by a predetermined distance (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.
1, q2 are the maximum values Xmax, Ymax, Zmax, and the minimum value X of the X, Y, and Z components 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 obtaining the intersection point i between the orthogonal planes P1 to Pn and the curve group C2, selecting the two most distant intersection points i in each orthogonal plane, and erasing the others is repeated over the orthogonal planes P1 to Pn. Perform (Step S4-
5 to S4-7). For example, the orthogonal plane Pm (1 <m <n)
Then, as shown in FIG. 7, the curve c constituting 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 which are most separated from each other are selected, and the other intersections i2 to i4 are deleted. I do. The intersections i1 and i5 selected in this way are defined as Sm1 and Sm2, respectively. This means that only the intersections that substantially form the outline L are selected. In this embodiment, the orthogonal planes P1, Pn
It is assumed that there is no intersection with the curve group C2. Further, the curve group C2 is deleted except for the intersection points 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 an orthogonal plane P2
ＰPn−1 and stored in the memory 16. Hereinafter, an outline L is created by connecting the intersections Sk1 and Sk2 (step S4-9) (see FIG. 9). 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 the orthogonal plane Pk 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 intersection points Sk1 and Sk2 related to the orthogonal plane Pk is read from the memory 16 and it is determined whether or not the intersection points Sk1 and Sk2 exist on the orthogonal plane Pk (step S4-9-2). ). In the present embodiment, first, the determination is made on the orthogonal plane P1, and the orthogonal plane P1 is determined.
Has no intersection, the determination is NO, and then j
= 1 is determined (step S4-9-3). Here, the orthogonal plane Pk is the intersection S
It is determined whether or not the plane is an orthogonal plane having no intersection next to 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. Subsequently, k = 2, that is, the orthogonal plane P2
Since there are intersections S21 and S22 in step S4,
YES is determined 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 forming the outline L. The orthogonal plane P2 is
Since it is the first plane (J = 0), the intersection S21 and the intersection S2
2 (step S4-9-6) (see the solid line in FIG. 8). Thereafter, k and j are each incremented (step S4-9-7), and the processing from step S4-9-2 is repeated. The intersection points S31 and S32 exist on the orthogonal plane P3 (step S4-9-2), and are not the first planes constituting 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 have been processed immediately before and the intersections each having a shorter distance (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). Thereafter, until k becomes n, k is incremented and the processing of step S4-9-2 and thereafter is repeated (step S4-9-9, step S4-9-10). If the intersection points Sn1 and Sn reach the orthogonal plane Pn
If there is an intersection 2, the intersection Sn1 and the intersection Sn2 are connected, and the creation of the outline L is completed (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. 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, an orthogonal plane Pn-1 having intersections Sn-11 and Sn-12 forming the outline L
Since this is the first orthogonal plane Pn without the next intersection,
As shown by a two-dot chain line, the intersections Sn-11 and Sn-12 on the orthogonal plane Pn-1 that have been processed immediately before are connected to complete the creation of the outline L (see FIG. 9). S4-
9-12). The area of the portion surrounded by the outline L thus obtained is calculated. Hereinafter, description will be made with reference to FIGS. First, as shown in FIG. 11, a coordinate system UV is set on a projection plane P, and an average value Vm = (Vmax +) is obtained from Vmax and Vmin in a region surrounded by the outline L.
Vmin) / 2. Subsequently, a straight line of V = Vm is drawn, and intersections T1 and T2 between the straight line and the outline L are determined. Next, the values U1, U of the intersections T1, T2 are
An average value Um = (U1 + U2) / 2 is obtained from U2, and FIG.
As shown in FIG. 2, a 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 formed at a predetermined angle, for example, 1 °.
Pull at ° intervals. Finally, the intersection T between the straight line M and the outline L
Are sequentially obtained, and the adjacent intersections Tk-1 and Tk and the center C
The area of the triangle formed by is calculated (see FIG. 14). The area of the area surrounded by the outline L is obtained by calculating the area of all the triangles and calculating the sum thereof, and displays the area on the CRT display 18. In the projection area calculation method using CAD according to the present embodiment, a curve group C which is three-dimensional graphic data to be projected is used.
1 and the projection plane P are specified, and the projection area calculation is performed by the CAD apparatus 1.
If 0 is indicated, an outline L of the automatically projected curve group C2 is created, and the area of the portion surrounded by the outline L is automatically calculated. Therefore, the operator sets the curve group C
It is not necessary to specify the second outline L, and the work efficiency is improved. In the present method, the projected curve group C2
The outline L is obtained from the intersection point i of the curve plane C1 and the orthogonal planes P1 to Pn.
Since it is set between the points q1 and q2 each consisting of the maximum value and the minimum value of X, Y and Z in the coordinate system, the orthogonal planes P1 to Pn cover a wider range than 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. According to the projection 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 figure data to be projected on the CAD apparatus and the projection plane are specified and the projection area calculation is ordered, the outline of the projected figure data is automatically created. , The projected area is calculated. Therefore, the operator is freed from troublesome work such as specifying the outline of the projected three-dimensional graphic data by an operator or the like, and an effect of improving work efficiency is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a CAD apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating a projection area calculation method according to an embodiment of the present invention. FIG. 3 is a flowchart showing a main part of a projection area calculation method according to one embodiment of the present invention. FIG. 4 is an explanatory diagram showing a method for creating an outline of a projected curve group in the projection area calculation method according to one embodiment of the present invention. FIG. 5 is an explanatory diagram showing a method for creating an outline of a projected curve group in the projection area calculation method according to one embodiment of the present invention. FIG. 6 is an explanatory diagram showing a method of creating an outline of a projected curve group in the projection area calculation method according to one embodiment of the present invention. FIG. 7 is an explanatory diagram showing a method for creating an outline of a projected curve group in the projection area calculation method according to one embodiment of the present invention. FIG. 8 is an explanatory diagram showing a method for creating an outline of a projected curve group in the projection area calculation method according to one 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 projection area calculation method according to one embodiment of the present invention. FIG. 10 is a flowchart illustrating an outline creation method in the projection area calculation method according to one embodiment of the present invention. FIG. 11 is an explanatory diagram showing an area calculation method in the projection area calculation method according to one embodiment of the present invention. FIG. 12 is an explanatory diagram showing an area calculation method in the projection area calculation method according to one embodiment of the present invention. FIG. 13 is an explanatory diagram showing an area calculation method in the projection area calculation method according to one embodiment of the present invention. FIG. 14 is an explanatory diagram showing an area calculation method in the projection area calculation method according to one embodiment of the present invention. [Description of Signs] 10 CAD apparatus 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

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Claims (1)

(1) A projection area calculation method for projecting three-dimensional graphic data onto an arbitrary plane in a CAD, and calculating an area of a projected image. A step of specifying figure data; a step of setting a projection plane; a step of projecting the three-dimensional figure data parallel to the projection plane from a normal direction of the projection plane; and a step of drawing the figure data projected on the projection plane. Medium, maximum values Xmax, Ymax, Zma of X, Y, Z in the XYZ coordinate system
x and the process of obtaining the minimum values Xmin, Ymin, Zmin, and the points (Xmax, Ymax, Zmax) composed of the maximum values
Setting a line segment connecting the 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 a predetermined distance from each other. And finding an intersection of the orthogonal plane and the projected graphic data,
Of the intersections on each orthogonal plane, leaving the two intersections with the longest separation distance between them, erasing the other intersections, and erasing the projected graphic data excluding the remaining intersections The process of creating an outline by connecting the intersection remaining on the orthogonal plane to the intersection of the shorter distance between the two intersections of the adjacent orthogonal plane, and the process of determining the area of the part surrounded by the outline And a projection area calculation method using CAD.