JP3886293B2 - Set calculation method of 3D curved surface shape - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a set calculation method for a three-dimensional curved surface shape, and more particularly to a three-dimensional shape input method, and more particularly, to a three-dimensional curved surface shape input method using three-dimensional CAD.
[0002]
[Prior art]
Conventionally, in the modeling of a three-dimensional shape using a three-dimensional CAD system, a collective operation, which is a method for defining a new shape by combining basic shapes, has been widely used.
In the set operation, there are a union that removes interference parts between three-dimensional shapes and put them together, a difference set that deletes interference parts from one shape, and a product set that takes out only the interference parts and defines them as new shapes.
As the basic shape, various shapes can be defined by using simple shapes such as a rectangular parallelepiped, a cylinder, and a sphere, a more complicated shape, and a shape of a set operation result.
As methods for defining a curved surface shape, various methods have been proposed in which not only a curved surface shape is directly input, but also a more complex curved surface shape is defined from a polyhedral shape that is simple and easy to handle.
[0003]
[Problems to be solved by the invention]
However, in the conventional method, there is a problem that, in a set operation for a curved surface shape, if the curved surface is complicated, the interference calculation takes time or the calculation fails due to the complexity.
In addition, the interference line obtained by calculation becomes a high-order or rational curve expression if mathematical accuracy is pursued, and there is a problem that it is difficult to handle or that error is difficult to handle if approximation is used for simplification.
In particular, the set operation result of curved surface shape usually uses a trimmed surface expressed by the combination of the curved surface before interference calculation and the interference line, but the trimmed surface handles errors when performing further set operations. And two curved surfaces used for interference calculation, there is a problem that one curve has two expression methods.
[0004]
In order to solve the above-mentioned problems, the present invention uses a technique for obtaining a curved surface shape that is more complicated than a simple polyhedron shape, and collects polyhedrons that are original shapes instead of performing a set operation between curved surface shapes. The object is to define a set operation of complex curved surface shapes as a fast and easy-to-handle shape by calculating and obtaining a curved surface shape from the resulting polyhedral shape.
[0005]
Here, rounding is used as a method for generating a curved surface shape that is more complicated than a simple polyhedron shape. Rounding is a method of generating fillets with a specified radius for polyhedral ridge lines, but this time we used "modeling method using the rounding operation of the transformation target solid and reverse rounding method and reverse rounding operation. A curved surface shape generation method by a rounding operation, which is a method in the “method (Japanese Patent Application No. 9-314697)”, is used.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 defines a curved surface shape by using a method of defining a curved surface shape from a polyhedral shape in a method of performing a set operation of a plurality of three-dimensional shapes constituted by curved surfaces by a graphic processing device. the set operation performed by the set operation processor relative polyhedral shape was the source, since the convex by dividing the concave surface of the polyhedral shape is a result of the set operation by the concave division processing unit, the curved shape forming unit It is characterized by generating a curved surface shape by applying a rounding operation.
[0007]
The invention according to claim 2 is characterized in that, in the invention according to claim 1, the set calculation processing means sets the polyhedron shape as a result of combining the interference parts of the polyhedron shape into one union. .
[0008]
The invention of claim 3 is characterized in that, in the invention of claim 1, the set operation processing means sets a polyhedron shape obtained by deleting the interference part of the polyhedron shape from one polyhedron shape as a difference set. .
[0009]
According to a fourth aspect of the present invention, in the first aspect of the invention, the set calculation processing means sets a polyhedron shape formed by the interference portion of the polyhedron shape as a product set .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing the configuration of a graphic processing / display apparatus to which the present invention is applied. This apparatus includes a CPU 1, a bus 2, a memory 3, an external storage device 4, an input device 5, and a display device 6. The present invention is realized by a system and a program operating on the computer system.
[0013]
FIG. 2 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 a curved surface shape generation unit 11, a set operation processing unit 12, a concave surface division processing unit 13, an input unit 14, It is composed of a shape storage unit 15 and a display unit 16, and an input device 21, an external storage device (shape data) 22, a display device 23, and the like are connected as external devices.
[0014]
FIG. 3 is a diagram showing the procedure of the curved surface shape set calculation as one embodiment of the present invention, and comprises the following STEP1 to STEP4.
STEP 1... Each curved surface shape is generated by applying a rounding operation to the polyhedron shape. The polyhedral shape (FIG. 4A) and the generated curved surface shape (FIG. 4B) are combined and held in the system.
[0015]
STEP 2... Perform union operation (FIG. 5B) of polyhedron shapes (FIG. 5A). Before executing the union, the curved surface shape is once deleted.
A difference set operation (FIG. 6B) between polyhedral shapes (FIG. 6A) is performed. Before executing the difference set, the curved surface shape is once deleted.
The intersection operation (FIG. 7B) of polyhedral shapes (FIG. 7A) is performed. Before performing the intersection set, the curved surface shape is once deleted.
[0016]
STEP 3... Of the polyhedron shape (FIG. 8A) as a result of the set operation, the concave surface is divided into convex surfaces (FIG. 8B). The convex surface division of the concave surface is performed as follows.
a) Examine the vertices of each face to find the concave vertices.
b) Define a coordinate system with the concave vertex as the origin. The Z coordinate axis of the coordinate system coincides with the normal vector of the surface, and the X coordinate axis of the coordinate system is defined to coincide with the line segment obtained by dividing the concave angle into two equal parts (FIG. 9).
c) Calculate the coordinates of all vertices of the surface in the coordinate system defined in the previous section.
d) Regarding the vertex coordinates after calculation, when the vertex is selected in order from the smallest X coordinate value and the absolute value of the Y coordinate value is small, and the concave vertex and the line segment are connected, Select vertices that do not intersect the edge.
e) A ridge line is generated between the vertex selected in the previous section and the concave vertex, and the concave surface is divided into two surfaces (FIG. 10).
f) The above processing is recursively performed on both sides after the division.
[0017]
STEP 4 ... The shape of the set operation between the curved surface shapes generated in STEP 1 by generating a curved surface shape by applying a rounding operation to the shape (Fig. 11A) obtained by dividing the concave surface of the polyhedron of the set operation result into a convex surface. Is obtained (FIG. 11B).
[0018]
【The invention's effect】
As is clear from the above description, the present invention has the following effects.
Curved shape of the result of executing any set operations can be obtained against multiple curved surface.
[0019]
It is possible to obtain a curved shape of the result of executing the union against multiple curved surface.
[0020]
It is possible to obtain a curved shape of the result of executing the set difference against multiple curved surface.
[0021]
It is possible to obtain a curved shape of the result of executing the set intersection against multiple curved surface.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a graphic processing / display apparatus to which the present invention is applied.
FIG. 2 is a functional block diagram showing a configuration of a three-dimensional CAD system according to an embodiment of the present invention.
FIG. 3 is a diagram showing a procedure of a curved surface shape set calculation as one embodiment of the present invention.
FIG. 4 is a diagram showing an example of generating a curved surface shape from a polyhedron shape.
FIG. 5 is a diagram showing an example of a union of polyhedral shapes.
FIG. 6 is a diagram illustrating an example of a difference set between polyhedral shapes.
FIG. 7 is a diagram illustrating an example of a product set of polyhedral shapes.
FIG. 8 is a diagram showing an example of convex surface division of a concave surface of a polyhedron having a concave surface.
FIG. 9 is a diagram illustrating an example of a coordinate system definition at a concave vertex of a concave surface;
FIG. 10 is a diagram showing an example of division from a concave vertex of a concave surface.
FIG. 11 is a diagram illustrating an example of curved surface shape generation by applying a rounding operation to a set operation result of a polyhedron shape.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... CPU, 2 ... Bus, 3 ... Memory, 4 ... External storage device, 5 ... Input device, 6 ... Display apparatus, 11 ... Curved surface shape production | generation part, 12 ... Set operation processing part, 13 ... Concave surface division | segmentation processing part, 14 DESCRIPTION OF SYMBOLS ... Input part, 15 ... Shape memory | storage part, 16 ... Display part, 21 ... Input device, 22 ... External storage device, 23 ... Display apparatus.

Claims (4)

In a method for performing a set operation of a plurality of three-dimensional shapes composed of curved surfaces by a graphic processing device, a method of defining a curved surface shape from a polyhedral shape is used, and the polyhedral shape from which the curved surface shape is defined is used. performing the set operation by a set processing means for, after the convex surface to divide the concave surface of the polyhedral shape is a result of the set operation by the concave division processing unit, by applying the rounding operation by the curved shape forming unit curved A set calculation method for a three-dimensional curved surface shape, wherein the shape is generated. 2. The set calculation method for a three-dimensional curved surface shape according to claim 1, wherein the set calculation processing means sets a polyhedron shape as a result of combining interference parts of the polyhedron shape into one union . 2. The set calculation method for a three-dimensional curved surface shape according to claim 1, wherein the set calculation processing means uses a polyhedron shape obtained by deleting an interference portion of the polyhedron shape from one polyhedron shape as a difference set . 2. The set calculation method for a three-dimensional curved surface shape according to claim 1, wherein the set calculation processing means uses a polyhedron shape formed by the interference portion of the polyhedron shape as a product set .

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