JPH0944696A - Polygon mesh connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect solid forms (polygon meshes) expressed by polygon with each other when three-dimensional modes to be used in three-dimensional CAD and three-dimensional CG fields are prepared. SOLUTION: When polygon meshes are connected with each other, the distances between vertexes are determined and the shortest distance of them is determined. For instance, a vertex P1 is selected from the vertexes of a polygon mesh A, the distances up to all the vertexes of a polygon mesh B are determined from this vertex P1 , the shortest distance is determined from the distances and the distance is defined as a correspondence point P1 '. Also, for all other vertexes P2 , P3 ,..., correspondence points P2 ', P3 '... are determined. Next, at the middle point between the corresponded vertexes, new vertexes are generated. Namely, at the middle points between the vertexes P1 -P1 ', the vertexes P2 -P2 ' and the vertexes P3 -P3 ', new vertexes Q1 , Q2 and Q3 are generated, respectively. After the new vertexes are generated for all the correspondences, new polygons defining the new vertexes as vertexes are generated and the connection of polygon meshes is performed. Lastly, old vertexes are deleted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polygon mesh connection device for connecting three-dimensional shapes (polygon meshes) represented by polygons (polygons).

[0002]

2. Description of the Related Art In the field of three-dimensional CAD and three-dimensional computer graphics (CG), as one of methods for creating a three-dimensional model, a certain model is photographed from several directions to obtain a partial shape. There is a method of connecting the plurality of partial shapes to create the entire shape of the three-dimensional model.
Each partial shape is represented by a polygon (polygon),
Connected by a polygon mesh device.

[0003] However, at present, practical methods and devices have not yet been proposed for the three-dimensional connection as described above.

[0004] By the way, as a connection technique of a two-dimensional shape (curve), the 1993 Annual Conference of the Institute of Image Electronics Engineers of Japan, 65
Maruya and Takashima's paper "Shape Reconstruction Using Texture as a Clue", which is published on pages 68-68, is known. With this method, when connecting two shapes consisting of two-dimensional point sequence data,
After obtaining the overlapping area by the average distance minimum method, the vertices in the overlapping area are associated with each other, and a new vertex is provided between the associated vertices to perform shape connection.

In this average distance minimization method, a certain overlap width is first assumed, then vertices are sequentially associated with each other by shifting by the overlap width, and the average of the sum of the distances between corresponding points is obtained. Perform the above processing for various overlapping widths,
Find the one with the smallest average distance.

The order of vertices is used for the minimum average distance method and the subsequent correspondence between vertices. Two
In a two-dimensional shape, all edges (sides) constituting the shape have two vertices and are connected only to another edge at that vertex. Therefore, all vertices are ordered using the connection relation. be able to. That is, if the rank of a certain end point is 1, the rank of the other vertex of the edge having the end point is 2, the rank of the vertex of another edge connected by the 2 vertices is 3, and the following. By performing the same operation, the order can be uniquely defined for all vertices.

[0007]

In the connection of the two-dimensional shape, all vertices can be ordered. Therefore, an overlapping width is introduced using this order relation, and the correspondence between vertices is uniquely determined thereafter. It was possible to do.

However, when connecting polygon meshes, it is generally impossible to order the vertices, and it is difficult to extend the conventional method to three dimensions as it is. Even if the overlap width can be introduced, there is a problem that the association cannot be uniquely determined just because the overlap width is determined.

The present invention has been made in view of the above points, and has as its object to provide a practical technique for connecting polygon meshes.

[0010]

In order to solve the above-mentioned problems, a polygon mesh connection device according to the first aspect of the present invention comprises:
When connecting three-dimensional shapes (polygon meshes) represented by polygons, a correspondence determining means for associating the vertices of two polygon meshes to be connected, and a new between the vertices associated by the correspondence determining means, A new vertex generating means for generating a new vertex, a polygon generating means for generating a new polygon using the new vertex generated by the new vertex generating means as a vertex, and a vertex unnecessary as a result of the polygon generating means is deleted. Old vertex deleting means.

According to a second aspect of the present invention, there is provided a polygon mesh connecting apparatus,
2. The apparatus according to claim 1, further comprising connection priority setting means for setting a connection priority, which is a parameter for controlling a generation position of a new vertex, to each vertex of the polygon, wherein the new vertex generation means newly sets the connection priority according to the connection priority. The position of the vertex to be generated is determined.

A polygon mesh connection device according to claim 3 is
3. The apparatus according to claim 2, wherein the connection priority setting means searches the end points of the polygon mesh and sets the lowest connection priority to the searched end points, and for each vertex of the polygon mesh. , After determining whether the connection priority has already been set, the connection priority that is adjacent to the vertex for which the connection priority has already been set and that has no connection priority is one step higher than the adjacent vertex. It is configured by the next rank connection priority setting means for setting.

According to a fourth aspect of the present invention, there is provided a polygon mesh connection device comprising:
3. The apparatus according to claim 2, wherein the connection priority setting means comprises: an endpoint determining means for determining whether a certain vertex is an endpoint;
Calculating the connection priority of the vertex based on the arrival point calculated by the end point arrival distance calculation means and the end point at which the distance along the polygon from the certain vertex along the polygon is the closest, and And a connection priority calculating means to be set.

[0014]

Next, an embodiment of the present invention will be described. FIG. 1 is a block diagram showing a first embodiment of a polygon mesh connection device according to the present invention. As shown in FIG. 1, this device determines correspondence between vertices of two connected polygon meshes. Means 11, a new vertex generating means 12 for generating a new vertex between the vertices associated by the correspondence determining means 11, and a polygon for newly generating a polygon with the new vertex generated by the new vertex generating means 12 as a vertex. It is composed of a generation unit 13 and an old vertex deletion unit 14 for deleting unnecessary vertices. The present device is constituted by a computer including a CPU, and the various functions of the means 11 to 14 are realized by the computer operating based on a predetermined program.

FIG. 2 is a diagram for explaining connection of polygon meshes, and shows polygon meshes A and B to be connected. These polygon meshes A and B are actually surface shapes, but are shown in cross section in FIG. 2 for explanation.

The correspondence determining means 11 makes correspondence between the vertices of the two polygon meshes A and B. As a means of this association, the distance to all the vertices of the polygon mesh B with respect to a certain vertex P of the polygon mesh A is determined, and the vertex of the polygon mesh B having the shortest distance is set as the corresponding point of the vertex P. However, this shortest distance is
If it is larger than a predetermined threshold value, no association is performed. The above processing is performed for polygon mesh A
For all vertices of.

The above processing will be described with reference to the flowcharts of FIGS. First, one vertex (for example, P ₁ ) is selected from the vertices of the polygon mesh A (step 301). Next, determine the distance to all vertices of the polygon mesh B from the apex P ₁ (step 30
2). The shortest distance is obtained from the obtained distances and this is set as the corresponding point P ₁ ′ (step 303). Further, the obtained shortest distance is compared with a predetermined threshold value (step 3).
04) If it is smaller than the threshold value, it is determined as a corresponding point (step 305). All the vertices P ₁ ,
Are repeated for P ₂ , P ₃ ,.
6). If it is determined in step 304 that the shortest distance is equal to or greater than the threshold value, it is determined that there is no corresponding point.
7) Go to step 306.

Next, in the new vertex creating means 12, the corresponding decision is made.
A new vertex at the midpoint between the vertices associated by the
Generate That is, as shown in FIG.
P₁−P₁´, vertex P₂−P₂´, vertex P_Three−P_ThreeAmong
At the midpoint, a new vertex Q₁, Q 2, Q_ThreeGenerate
You.

When new vertices are created for all the correspondences, the new vertex creating means 1
A new polygon having the new vertex created in 2 as a vertex is generated, and a polygon mesh is connected. Thereafter, the old vertex deleting means 14 deletes the vertex which is no longer required as a result of the connection, and completes a series of connection processing (see FIG. 2B).

Next, a second embodiment of the polygon shape connecting device will be described with reference to FIGS.

This polygon mesh connection device includes a connection priority setting means 21 in addition to the polygon mesh connection device of the first embodiment in order to realize smooth polygon mesh connection. The connection priority setting means 21 sets “connection priority” for each vertex of the polygon mesh. The “connection priority” is a parameter given to each vertex of the polygon, and is generally set so as to be lower toward the end and higher toward the center. For example, FIG.
As shown in the figure, low-priority "1" is set at the end portions of the polygon meshes A and B, high-priority "3" is set at the central portion, and priority "2" is set at the intermediate region. It has been set.

First, the correspondence determining means 11 performs the same processing as that of the apparatus of the first embodiment.

Next, a new vertex is created by the new vertex creating means 12 for the corresponding point obtained by the corresponding point determining means 11, and at this time, according to the connection priority set by the connection priority setting means 21. Weighting is performed. That is,
Assuming that the connection priority of the corresponding point of the polygon mesh A is a and the connection priority of the corresponding point of the polygon mesh B is b, a point that internally divides the line connecting the corresponding points into b: a is created as a new vertex. I do. Incidentally, polygon meshes also connecting portion to the other, b n according to the distance, the m as any real number ^m for this weighting: a method which internally divides a ⁿ are conceivable.

More specifically, as shown in FIG.
The new vertex Q ₄ is a new vertex when the priority of the vertex of the polygon mesh A is “1” and the priority of the vertex of the polygon mesh B is “3”. The vertex Q ₄ has a distance of 3:
1, which is set closer to the polygon mesh B having a higher priority. The vertex Q ₆ is set so that the distance between the two is internally divided into 1: 3, and is closer to the polygon mesh A having a higher priority. Vertex Q ₅ is because polygon mesh A, the priority of the vertices of B are the same "2" is set to both the midpoint.

Further, the above-mentioned b ^m: According to the method which internally divides a ^n, When n = 1, m = 2, the vertex Q ₄ are, the distance therebetween is 3 ^2: 1 ¹ (i.e., 9: 1) and is set closer to the polygon mesh B.

After that, the polygon generating means 13 and the old vertex deleting means 14 perform the same processing as in the first embodiment.

Next, FIG. 6 is a block diagram showing a third embodiment of the polygon mesh connection device. This embodiment shows an example of a method of setting the priority with respect to the connection priority setting means. Other components are the same as those of the second embodiment.

In this embodiment, when setting the connection priority,
As shown in FIG. 7A, “1” having the lowest priority is set at the end of the polygon mesh. Next, FIG.
As shown in (c), the priority is increased toward the inside of the polygon mesh and set to “2”, “3”, and the like.

The connection priority setting means 22 of this embodiment sets the connection priority step by step. As shown in FIG. 6, an end point of the polygon mesh is searched, and the searched end point is Initial connection priority setting means 31 for setting a low connection priority, and determining whether or not a connection priority has already been set for a certain vertex, and then determining a connection priority adjacent to the vertex for which a connection priority has already been set. And a next-rank connection priority setting means 32 for setting a connection priority one level higher than a vertex adjacent to a vertex whose degree has not been set.

The operation of each processing unit will be described with reference to the flowchart of FIG. The initial connection priority setting means 31 first selects a vertex from among the vertices of the polygon mesh (step 71), and determines whether or not the vertex is an end point (step 72). If the vertex is determined to be the end point, the connection priority of the lowest rank (for example, “1” in FIG. 7) is set (step 73), and the connection priority is not set for the vertex that is not the end point (step 73). 7
4). The above processing is performed for all vertices (step 75).

Here, when there is a polygon having a vertex as a constituent point and not sharing an edge (side) with another polygon, the vertex is defined as an "end point". For example, the vertices P ₁ and P ₃ ′ in FIG. 2A are end points.

There are various methods for determining the end point in step 72. For example, the following method can be used. That is, all polygons having the vertices as constituent points are obtained, and then all vertices forming each polygon are listed. If any of the vertices thus listed has an odd number of vertices, the original vertex is determined to be an end point of the polygon mesh.

The next rank connection priority setting means 32 first selects a vertex having a polygon mesh (step 7).
6) It is determined whether a connection priority has already been set for this (step 77). If connection priorities have already been set, it is checked whether connection priorities have been set for all vertices (step 78). If not, the process returns to step 76 and performs the same processing. Step 77
If the connection priority has not been set, the adjacent vertices are checked. If there is at least one adjacent vertex for which the connection priority has been set (step 79), the connection is higher by one level than the adjacent vertex. Set priority (step 8
0). For example, considering the vertex P in the case of FIG. 7A, the priority of the vertex adjacent to the vertex P is “1”, and the priority of the vertex P is “2” as shown in FIG. Becomes Similarly, as shown in FIG. 7C, “3” is set after “2”.

The above processing is repeated until there are no vertices for which connection priority has not been set, and connection precedence is set for all vertices. Note that the connection priority setting means 22 of the present embodiment
It can also be used when connecting dimensional shapes.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, another example of the connection priority setting means is shown.
Is the same as the embodiment described above.

The connection priority setting means 23 of this embodiment sets the connection priority based on the shortest route to the end point without performing stepwise processing, and determines whether the vertex is an end point. Endpoint determining means 51 for determining, and endpoint reaching distance calculating means 52 for obtaining the shortest path from the vertex to the endpoint
And connection priority setting means 53 for setting the connection priority based on the end point reach distance.

Next, the operation of each section will be described. The end point judging means 51 performs the same processing as the end point judging method in the initial connection priority setting means 31 of FIG. 6, and judges whether or not each vertex is an end point for all the vertices of the polygon mesh. Next, in the end point arrival distance calculation means 52, a route along the polygon mesh from the certain vertex for which the connection priority is to be set to the vertex determined as the end point by the end point determination means 51 is obtained. Calculate the shortest path.

Then, in the connection priority calculating means 53,
A value obtained by adding a real number (may be 0) to the shortest reach distance calculated by the end point reach distance calculating means 52 is calculated as the connection priority, and set to the vertex thereof.

The processing by the end point reach distance calculation means 52 and the connection priority calculation means 53 is performed on all the vertices of the polygon mesh to set the connection priority. Note that the connection priority setting unit 23 of the fourth embodiment can also be used when connecting two-dimensional shapes.

[0040]

According to the present invention, the correspondence between the vertices is determined by the corresponding point determination unit without using the order relation of the vertices.
Polygon mesh connection was realized.

Further, since the connection is made after weighting using the connection priority set by the connection priority setting means, a smoother polygon mesh connection can be performed. If the distance between polygon meshes is large,
Especially effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a view for explaining the operation of the apparatus of FIG. 1;

FIG. 3 is a flowchart explaining the operation of the apparatus of FIG.

FIG. 4 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 5 is a view for explaining the operation of the device in FIG. 4;

FIG. 6 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 7 is a view for explaining how to determine a connection priority;

FIG. 8 is a flowchart for explaining the operation of the apparatus in FIG. 6;

FIG. 9 is a diagram showing a configuration of a fourth embodiment of the present invention.

[Explanation of symbols]

 11 Correspondence determination means 12 New vertex creation means 13 Polygon generation means 14 Old vertex deletion means 21, 22, 23 Connection priority setting means 31 Initial connection priority setting means 32 Secondary rank connection priority setting means 51 Endpoint determination means 52 End point arrival Distance calculation means 53 Connection priority calculation means

Claims (5)

[Claims] 1. A polygon mesh connecting device for connecting three-dimensional shapes expressed by polygons, wherein
Correspondence determining means for associating the vertices of the two polygon meshes, new vertex generating means for generating a new vertex between the vertices associated by the correspondence determining means, and a new vertex generating means generated by the new vertex generating means. A polygon mesh connection device, comprising: a polygon generating means for generating a new polygon with vertices as vertices; and an old vertex deleting means for deleting unnecessary vertices. 2. A connection priority setting means for setting a connection priority, which is a parameter for controlling a generation position of a new vertex, to each vertex of a polygon, wherein the new vertex generation means newly generates a new vertex according to the connection priority. The polygon mesh connection device according to claim 1, wherein a position of a vertex to be generated is determined. 3. An initial connection priority setting means for searching for an end point of a polygon mesh and setting a lowest connection priority to the searched end point; and for each vertex of the polygon mesh, After judging whether the connection priority has already been set, adjacent to the vertex for which the connection priority has already been set, to the vertex for which the connection priority has not been set, from the vertex for which the connection priority has been set 3. The polygon mesh connection device according to claim 2, further comprising: a next rank connection priority setting means for setting a connection priority one level higher. 4. An end point determining means for determining whether a certain vertex is an end point, an end point closest to a polygonal path from a certain vertex, and an end point reach distance calculation for obtaining the end point. 3. The polygon mesh connection device according to claim 2, further comprising: a connection priority calculating unit configured to calculate and set a connection priority of the vertex based on the arrival distance calculated by the end point arrival distance calculation unit. . 5. A polygon mesh connecting method for connecting three-dimensional shapes represented by polygons, which comprises connecting 2
Performing the correspondence between the vertices of the three-dimensional shapes, generating a new vertex between the associated vertices, generating a new polygon with the new vertex as a vertex, and deleting the unnecessary vertex. Characteristic polygon mesh connection method.