JP3143464B2 - Apparatus and method for creating three-dimensional model - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus and method for creating a three-dimensional model from a two-dimensional drawing.

[Related Art] The following method is known as a method for generating a three-dimensional solid model from a two-dimensional drawing.

・ H.sakurai and DCGossard, “Solid model input
through orthographic view ", ACM Computer Graphics, V
ol.17, NO.3, July 1985, pp.243-252 In such a method, a three-dimensional wireframe model is once created from a two-dimensional three-view drawing, and a solid model is created based on this.

・ V.NAgasamy and NALangrana, “Reconstruction o
f 3D objects using a kd environment ", ASME Computer
s in Engineering 1989, Vol. 1, July 1989, pp. 117-126 A method of extracting basic solids constituting a solid from a drawing and combining these basic solids to generate a solid model [Problems to be Solved by the Invention] When considering the use form of CAD in the product development process, it is desirable to target a two-dimensional drawing that is easy to operate and represent in design, and a three-dimensional model that can accurately represent the product shape in the process after design. For that purpose, conversion from a two-dimensional drawing to a more advanced solid model is necessary. However, at present, no method has been established for realizing conversion from a two-dimensional drawing to a solid model at a practical level.

In the method via a wire frame represented by the first known example described above, (1) Unnecessary edges are generated in the process of generating a three-dimensional wire frame model, and the work of removing the unnecessary edges is performed. is necessary.

(2) There are many restrictions on the conversion from the wire frame model to the solid model.

(3) The calculation load is extremely high to create a solid candidate model for any combination of shapes conceivable from a wireframe model, and in order to select a solid model from among the candidates, Create multiple models.

(4) It has the drawback that no drawing errors or calculation errors are allowed.

The method described in the following known example is also effective for a simple drawing, but (5) basically cannot be handled if the shape becomes complicated because pattern matching is performed in a naive manner. become.

(6) When the drawing contains a minute error, runaway of calculation is easily caused.

It has the drawback.

The present invention overcomes these drawbacks and provides two-dimensional
/ Realize 3D conversion.

[Means for Solving the Problems] A three-dimensional model creation apparatus according to the present invention includes: a cut plane generating unit configured to generate a cut plane of a three-dimensional model based on a plurality of two-dimensional drawings; Phase information generating means for generating phase information of a surface constituting the three-dimensional model based on a change between the two, and three-dimensional model generating means for generating a three-dimensional model based on the generated phase information. It is characterized by.

Further, the method of creating a three-dimensional model according to the present invention includes the steps of: generating a cut plane of the three-dimensional model based on a plurality of two-dimensional drawings; Generating the phase information of the surface constituting the phase information and storing the generated phase information in the phase information storage means; and 3 based on the phase information stored in the phase information storage means.
Creating a dimensional model.

Example First, the outline of the present invention will be specifically described.

In the present invention, as a means for creating a three-dimensional model from a two-dimensional drawing, the two-dimensional drawing is once made 2.5-dimensional,
From the cut surface shape of the solid created while recognizing the entity existence space realized in the 2.5D drawing, the connection information of the surfaces that make up the 3D solid, the features of the surface itself, that is, the topology information and geometry information of the surface Is extracted, and a three-dimensional model is created from the two pieces of information completely independently of the two-dimensional drawing.

With this configuration, according to the present invention, the topology information and the geometry information of the surface extracted from the two-dimensional drawing are determined first, and then the edge calculation for generating the three-dimensional model is performed. Even when the shape is complicated, the load of calculation is light, and a two-dimensional drawing can be stably converted to a three-dimensional model without runaway or outputting a plurality of ambiguous shapes due to calculation errors. Also, in the case of dealing with drawings containing contradictions and errors in the future, it is possible to flexibly respond by interactively modifying the obtained topology information and geometry information interactively.

FIG. 1 is a block diagram illustrating one embodiment of the present invention. In the figure, reference numeral 10 denotes a processing device, in which a processing program of a procedure as shown in FIG. , 11 are realized. Reference numeral 12 denotes a display device that displays a model of a processing result, an input drawing, or a drawing during processing. Reference numeral 13 denotes an input device for inputting edit, correction, position and correction commands and messages for giving instructions to the processing device by using a key, a cursor or an icon. A storage device 14 stores a two-dimensional CAD drawing as input data to be processed. Reference numeral 15 denotes an external storage device that outputs a three-dimensional solid model as a processing result. A network interface 16 communicates with an external system. In the modeling system 11, reference numeral 20 denotes a topology information / geometry information extraction unit. A storage unit 21 stores the extracted topology data of the surface. Reference numeral 22 denotes a storage unit that stores surface geometry data. 23 is an edge trace / solid model creation unit.

The processing of the present invention having the above configuration will be described with reference to the drawings.

First, two-dimensional CAD drawing data is loaded from an external storage device 14 into a memory in the processing device 10 in accordance with an instruction from the input device 13.

Next, a processing instruction is input according to an instruction from the input device 13, and first, the topology information / geometry information extracting unit 20
Then, based on the two-dimensional drawing data, topology data and geometry data of a surface constituting a three-dimensional solid represented by the drawing are generated and stored in the storage units 21 and 22, respectively. When such processing is completed, the edge trace /
The solid model creation unit 23 performs a process of generating a three-dimensional solid model from the topology data and the geometry data of the surface. The three-dimensional solid model generated by such processing is stored in the external storage device 15. Such a result is also displayed by the display device 12.

Next, detailed processing in each of the above processing units will be described for each processing unit.

First, with respect to the topology information / geometry information extraction unit 20 shown in FIG.
Steps: 2.5-dimensional drawing, second step: setting of cutting level, third step: creation of cut plane, fourth step
In the step, each step of the topology scan and in the fifth step, the processing of creation of the topology and the geometry data of the surface are executed.

Step 1. Making the drawing 2.5-dimensional In other words, as shown in FIG. 3a, by adding a shape (surface shape) in the height direction of the region to the closed region on the two-dimensional drawing, FIG. Create 2.5-dimensional surface data as shown in.

1) A surface shape is defined for an area in which information in the height direction can be uniquely recognized from the correspondence on the drawing.

2) Similarly, a hole is defined for an area that is clearly determined to be a hole from the correspondence on the drawing.

3) For an area that cannot be automatically recognized, a surface shape is instructed by an operation.

Step 2. Setting of cutting level This apparatus determines the geometric phase of the entire shape by reading the change in the geometric phase of the cutting plane in each of the XYZ directions.
For this purpose, since any small change in each direction must not be overlooked, all points where a change in the geometric phase can occur are picked up, and a cutting level is set so as to cut a section (shape feature section) therebetween.

Step 3. Creation of cut plane Based on the 2.5-dimensional data, the cut plane shape in the shape characteristic section in each of the X, Y, and Z directions is created as shown in FIG. Creation of such a cut plane-There is no entity on the near side (= line of sight) of the surface defined as an entity on the 2.5-dimensional drawing.

-There is a semi-infinite space (= entity existence space) where the entity is located behind the area defined as the entity on the 2.5D drawing.

-There is no entity on the front or back side of the area defined as a hole on the 2.5-dimensional drawing.

・ The three-dimensional space actually represented by the drawing is the view on the drawing
It is expressed in the form of a logical product of the entity existence space claimed by (~ view).

 The following processing is performed in consideration of the above points.

1) Set a cutting plane.

2) Within the cutting plane, create a semi-infinite (actually finite) cut shape that represents the semi-infinite entity existence space claimed by each VIEW.

3) Obtain the logical product of the semi-infinite cutting shapes of each view to obtain a three-dimensional cutting surface shape.

Step 4. Topology Scan The shape of the cut surface is scanned in each of the X, Y, and Z directions as shown in FIG. 5 to recognize a change in the phase between adjacent surfaces, and the surface connection information is accumulated. That is, processing is performed in consideration of the following points.

When a cut surface is created in fine increments in each of the X, Y, and Z directions, and this is scanned, a change in the connection relationship between the surfaces constituting the cut surface can be recognized.

When a combination of planes that did not exist at the previous cutting level appears in the comparison in the scanning direction, this is recognized as plane-to-plane connection information that forms a solid.

The actual cutting position is a section (= shape feature section) between shape feature points in the X, Y, and Z directions on the drawing.

 The following processing is performed in consideration of the above points.

1) Surface attribute information is added to each element (element) of the cut surface shape.

2) An attribute that scans in each of the X, Y, and Z directions, recognizes a change in the phase of the cut plane before and after the scan direction, and adds connection information between the cut plane elements of the changed portion to each element of the cut plane. The information is stored as surface-to-surface connection information.

Step 5. Generation of Topology / Geometry Data of Surface 1) Connection information of each surface is arranged in units of surfaces and stocked as connection information of surfaces.

2) Generate surface and geometry data from the type and surface shape of each surface.

Next, the edge trace / solid model creation unit 23 shown in FIG. 1 will be described in detail.

First, a graph search is performed based on the connection information of the recognized surfaces. Perform loop ranking of adjacent faces. The edge is calculated from the surface where the adjacency relation is determined, and a B-reps type solid model having a Winged-edge structure is created. In other words:-Surface connection information (topology) extracted from the drawing by topology scanning and the surface shape (geometry) of that surface
Based on this information, the edge of the surface is determined.

-A graph search method is used to determine the loop division of adjacent planes and the arrangement of adjacent planes.

-The edge is determined by performing an intersection calculation between the surfaces for which the adjacent relationship has been determined.

 The following processing steps are performed in consideration of the above points.

1) Receiving surface topology data (adjacent surface information, unevenness information) and geometry data (surface shape information).

2) Using a graph search based on the adjacent plane information, loop division of the plane and determination of the arrangement order of adjacent planes in the loop are performed.

3) In accordance with the determined order of the loops, the intersections between adjacent planes are sequentially calculated to create edges.

4) Generate solid model data from the created edge information.

By processing as described above, processing of a three-dimensional model from a two-dimensional drawing can be efficiently realized.

[Effect] According to the present invention, it is possible to efficiently create a three-dimensional model without imposing a load on a user even for a two-dimensional drawing having a complicated shape.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an embodiment of the present invention, FIG. 2 is a diagram showing a processing procedure for explaining an embodiment of the present invention, and FIG. 3a is processed by an embodiment of the present invention. FIG. 3b shows an example of information processed by an embodiment of the present invention. FIG. 4 shows an example of information processed by an embodiment of the present invention. FIG. 20 showing an example of information processed according to the embodiment of the present invention 20 Topology information / geometry information extraction unit 21 Topology data storage unit 22 Surface geometry data storage unit 23 Edge trace / solid Model creation section

Continuation of the front page (56) References JP-A-62-105271 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06T 1/00 G06T 11/60-17/50 G06F 17 / 50

Claims (2)

(57) [Claims] 1. A cutting plane generating means for generating a cutting plane of a three-dimensional model based on a plurality of two-dimensional drawings, and a plane constituting the three-dimensional model based on a change between the generated plurality of cutting planes. A three-dimensional model generating device for generating a three-dimensional model based on the generated phase information; and a three-dimensional model generating device for generating a three-dimensional model based on the generated phase information. 2. A step of generating a cut plane of a three-dimensional model based on a plurality of two-dimensional drawings, and phase information of a plane constituting the three-dimensional model based on a change between the generated plurality of cut planes. Generating a three-dimensional model based on the phase information stored in the phase information storage means; and generating a three-dimensional model based on the phase information stored in the phase information storage means. How to create a dimensional model.