JP3057178B2 - Conversion method of CAD data in 3D model - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for converting data of a three-dimensional model in a three-dimensional CAD system.

[0002]

2. Description of the Related Art In a three-dimensional CAD system, the shape and the like of a three-dimensional model are read as data. 2. Description of the Related Art Conventionally, techniques for expressing the shape and the like of a three-dimensional model as data include a technique based on a surface representation and a technique based on a solid representation.

[0003]

When a complex three-dimensional model is represented by the surface representation or solid representation described above, the amount of data inevitably becomes enormous, and when a computer performs a predetermined operation, the operation time is extremely long. For example, there were drawbacks requiring several days or more.

[0004] Accordingly, the present invention provides a method for forming a shape data of a three-dimensional model.
Data into data that reduces the amount of data
It is an object of the present invention to provide a method for converting CAD data in a three-dimensional model to be obtained .

[0005]

In order to solve the above-mentioned problems, a first means of the present invention is a computer-readable medium created by a CAD system.
Shape data representing the surface of the
And loading the data into the
Enclosing a projection of a three-dimensional model on a plane by a rectangular line, dividing the rectangular plane enclosed by the rectangle vertically and horizontally by a straight line, and the rectangular plane starting at each intersection of these division lines A step of obtaining an intersection between a perpendicular line perpendicular to the three-dimensional model surface and the coordinates of each intersection point of the dividing line, a distance from the rectangular plane to the three-dimensional model surface in the perpendicular line,
And the distance between the intersection of the perpendicular with the solid model surface is stored as data.
The three-dimensional model comprising a step of converting the data into linear data
This is a method for converting CAD data .

[0006] A second means of the present invention is a CAD system.
Data representing the surface of the three-dimensional model created by the system
Loading the data into the computer
A step of enclosing a projection of a three-dimensional model based on the shape data on a plane with a rectangular line, a step of vertically and horizontally dividing the rectangular plane surrounded by the rectangle by a straight line, and setting each intersection of these division lines as a starting point. A step of obtaining an intersection between the perpendicular line perpendicular to the rectangular plane and the three-dimensional model surface, the coordinates of each intersection of the dividing lines, the distance from the rectangular plane to the three-dimensional model surface in the perpendicular line, and the three-dimensional model surface in the perpendicular line The distance between the intersections of the three-dimensional model is divided by a predetermined reference distance in the three-dimensional model, and the resulting data is stored as data.
CAD data in the three-dimensional model comprising a step of conversion
Is a conversion method.

[0007] According to the configuration of each of the above means, the CAD system
Shape data representing the surface of the three-dimensional model created by
Read into the computer, the shape data, the intersection coordinates of the straight line of the vertical and horizontal obtained on the projection plane, Oyo
Since the data is converted into data on the distance to the surface of the three-dimensional model or the distance of the penetrating part penetrating the three-dimensional model from the intersection point of the projection and the perpendicular line perpendicular to the projection plane and stored, the data to be stored in the solid model, for example, is stored. Only a very small amount of data is required.

Further, by dividing the distance data by a predetermined reference distance to make it dimensionless, it becomes easy to compare it with the shape of another three-dimensional model having different dimensions.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a three-dimensional model of the present invention will be described.
1 to 3 show an embodiment of a CAD data conversion method according to the present invention.
It will be described based on. In the present embodiment, a case where a connecting rod 1 as shown in FIG. 1 is used as an object of a three-dimensional model will be described.

First, shape data of a solid model (of course, shape data of another model) of the connecting rod 1 created by an ordinary CAD system is read into a computer (not shown). Next, a quantization unit length u for dimensionless distance data described later is obtained. First, as the reference length of the three-dimensional model, both ends of the connecting rod 1, that is, a hole 2 which is a small end,
The center distance B with the semicircular boss 3 which is the large end is read (or obtained), and the number n of divisions for appropriately dividing the center distance B is read (or input). The distance B is divided by the number of divisions n, and this value (B /
Let n) be the quantization unit length u.

Next, the entire projected view projected onto a predetermined plane of the connecting rod 1 is surrounded by a rectangular line 11, and a rectangular plane 12 surrounded by the rectangle is defined by a straight line 1
3 is divided vertically and horizontally. Note that the interval between the dividing straight lines (hereinafter, referred to as dividing lines) 13 is set to the quantization unit length u, and therefore, the short side 12a and the long side 1
2b is a length (L _y , L _x ) that is a multiple of the quantization unit length u.
It is said.

Next, each intersection point P of the above dividing line 13
_ij (P _mn ) and the intersection P _ij
, A perpendicular line (a straight line parallel to the z-axis) 14 perpendicular to the rectangular plane 12 is prepared, and each intersection point M _ij1 , M _{ij2 of} each perpendicular line 14 and the surface of the connecting rod 1 is formed.
The coordinates of (M _ijk ) are obtained. Next, at each perpendicular 14, the distance Ls _ij1 (Ls _ijk ) from the rectangular plane 12 to the connecting rod 1 and the distance Lc _ij1 (Lc _ijk ) between the surfaces of the connecting rod 1 at each perpendicular 14.
Is obtained by calculation. Of course, these distances Ls _ij1 , L
When _obtaining c _ij1 , each of the intersections P _ij , M _ij1 , M _ij2
Coordinates are used.

In the drawing, only the case of P _ij is shown. Next, each of the distances Ls obtained above is calculated.
_ij1 (Ls _ijk ), Lc _ij1 (Lc _ijk ) are made dimensionless by dividing by the reference length B of the connecting rod 1, and are used as representative values of the connecting rod 1 at each intersection. Then, each of these data, namely the intersection coordinates in the rectangular plane 12, and the dimensionless distance, three-dimensional
The data is converted and stored as data representing the shape of the model.

FIG. 2 is a flowchart showing the above procedure. FIG. 3 shows the data converted and stored by the above procedure. That is, the three-dimensional model of the connecting rod 1 shown in FIG. 3A is represented (converted ) as a set of line segments (linear data) as shown in FIG. The data amount of the data indicating the shape of is very small.

For example, compared to a solid model having a complicated shape such as a connecting rod,
The data amount is about 100 to 1/500. Also, as described above, since the three-dimensional model is represented by a set of line segments, for example, when combining a certain large three-dimensional model and a small three-dimensional model to produce a three-dimensional model of an intermediate shape, It is enough to combine data of line segments,
Therefore, the synthesizing operation can be performed in a very short time and easily.

Although not described in the above embodiment, as shown in FIG. 4, for example, when the three-dimensional model 21 has a concave portion 22, the perpendicular 34 of that portion is It penetrates both sides (upper and lower parts in the drawing). In this case, the distances Lc _ij1 and Lc _ij2 of the upper and lower penetrating parts 21 a and 21 b in the recess 22, the distance Ls _ij1 from the rectangular plane 32 and the distance between the penetrating parts The distance Ls _ij2 of the space 23 is also stored as data.

In the above embodiment, when the distance is made dimensionless, the center-to-center distance B between the small end and the large end is determined.
The reason why the center-to-center distance B is selected is that, for example, when combining this three-dimensional model with another three-dimensional model of the same type, the degree of similarity with other three-dimensional models of the same type is selected. This is because it is convenient when checking. Therefore, for example, when consideration is not given to synthesis with another three-dimensional model, the distance data does not have to be dimensionless.

[0018]

As described above, according to the structure of the present invention, C
Shape representing the surface of the solid model created by the AD system
Read the shape data into a computer
The coordinates of the straight line of intersection of the vertical and horizontal obtained on the projection plane, the data of the distance of the penetrating part which penetrates the distance and three-dimensional model to the three-dimensional model surface the intersection at the start point Toshikatsu projection plane perpendicular perpendicular Since the data is converted and stored, for example, in the case of a three-dimensional model having a complicated shape, the data amount is very small compared to the amount of data to be stored in the solid model. In addition, the calculation time for checking the degree of suffices, and the handling of data becomes easy.

Further, by dividing the distance of the three-dimensional model by a predetermined reference distance to make it dimensionless, it is possible to easily compare the three-dimensional model with a shape of another three-dimensional model having different dimensions.

[Brief description of the drawings]

FIG. 1 is a perspective view of a model of a connecting rod according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure for converting data of the connecting rod.

FIG. 3 is a diagram comparing a solid model of the connecting rod and a case where the solid rod is converted by the method of the present invention;
3 is a diagram showing a solid model, and FIG. 3B is a diagram showing a state converted by the method of the present invention.

FIG. 4 is a schematic diagram illustrating a main part of a procedure for converting shape data of a surface of a connecting rod model according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connecting rod 2 Hole part 3 Boss part 11 line 12 Rectangular plane 13 Division line 14 Perpendicular line

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-67678 (JP, A) JP-A-6-44363 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 17/50 G06T 17/00

Claims (2)

(57) [Claims] 1. A three-dimensional model created by a CAD system.
Read the shape data representing the surface of the
And a 3D model based on the loaded shape data
A step of enclosing the projection view obtained by projecting the plane rectangular lines, the step of dividing the rectangular plane surrounded by the rectangle vertically and horizontally by straight lines, perpendicular to the rectangular plane starting from each intersection of these dividing lines The step of determining the intersection of the perpendicular and the solid model surface, the coordinates of each intersection of the dividing line, the distance from the rectangular plane in the perpendicular to the solid model surface, and the distance between the intersection of the perpendicular with the solid model surface Each data is stored as data, and the shape data of the three-dimensional model is linear data.
Converting to a three-dimensional model
Method of converting CAD data in the above. 2. A three-dimensional model created by a CAD system.
Read the shape data representing the surface of the
And a 3D model based on the loaded shape data
A step of enclosing the projection view obtained by projecting the plane rectangular lines, the step of dividing the rectangular plane surrounded by the rectangle vertically and horizontally by straight lines, perpendicular to the rectangular plane starting from each intersection of these dividing lines The step of determining the intersection of the perpendicular and the solid model surface, the coordinates of each intersection of the dividing line, the distance from the rectangular plane in the perpendicular to the solid model surface, and the distance between the intersection of the perpendicular with the solid model surface Dimensions obtained by dividing by a predetermined reference distance in the three-dimensional model are stored as data, and the shape of the three-dimensional model is stored.
Converting the data into linear data .