JP3463843B2 - Free-form surface generation apparatus and free-form surface generation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free-form surface generating apparatus and a free-form surface generating method, and more particularly to generating a free-form surface using point cloud data and extracting characteristic points satisfying a predetermined condition from the point cloud data. The present invention relates to a free-form surface generation device and a free-form surface generation method that extract and correct a curved surface using the feature points.

[0002]

2. Description of the Related Art Conventionally, CAD (Computer Aided Desired)
gn) / CAM (Computer Aided Manufacturing) system is used to represent a desired shape in a virtual space on a computer, and by appropriately modifying this, it is possible to design the shape of an object having a free-form surface. Has become.

In the CAD / CAM system, by inputting some points (nodes) through which a desired curve passes,
A smooth curve passing through those points can be represented in a virtual space on a computer. These curves are realized by the computer performing a predetermined vector operation on the input points, for example, an operation such as a Bezier equation or a B-Spline equation.

Then, after a rough shape to be designed by the user is generated by these plural curves, the area surrounded by the curves is interpolated by a predetermined curved surface (patch) obtained by a predetermined vector operation. It is possible to obtain a desired free-form surface.

However, in order to generate a three-dimensional complex free-form surface by inputting all the nodes using a two-dimensional input device such as a keyboard and a mouse as described above, appropriate skill is required. It also takes time.

Therefore, the shape of a three-dimensional model is measured using a three-dimensional measuring device or the like with respect to a predetermined existing model, and the measurement result data is input to CAD / CAM. It has been proposed to generate a free-form surface by processing.

For example, with respect to the model shown in FIG. 13, the three-dimensional shape of a square lattice is measured, and based on the measurement result,
Square-lattice point cloud data as shown in FIG. 14 is generated. Then, a spline curve can be interpolated to these point cloud data to generate a free-form surface image as shown in FIG.

Further, the shape of a cross section in the same direction is measured for a predetermined model as shown in FIG. 16, and an approximated sectional curve as shown in FIG. 17 is generated based on the measurement result.
Then, by interpolating the spline curve in the direction in which these cross-sectional curves are arranged, a free-form surface image as shown in FIGS. 18 and 19 can be generated. In this process, as shown in FIG. 19, fine stitch patterns are formed on the free curved surface.

Further, for example, as shown in FIG. 20, a characteristic portion is set in advance with respect to a predetermined model, and the shape of the characteristic portion is measured and converted into data.
As shown in 3, a curve for the characteristic part is generated.
Then, a curved surface can be interpolated between these curves to generate a free-form surface image.

[0010]

However, as shown in FIG.
16 to 19 and the method described with reference to FIG.
In the method described using, the data obtained as the measurement result is composed of the data based on the overall shape of the model (because it is not composed of the data of only the predetermined characteristic part), so the data amount is large. turn into. Further, in these methods, since the independence of the data forming the curved surface is low (because they are not separated in units of basic curved surfaces), for example, fillet processing (processing for smoothly connecting basic curved surfaces having different characteristics) is performed. Even when you do
The fillet diameter and fillet shape cannot be easily changed.

On the other hand, in the case where the free-form surface image is generated by extracting the characteristic portion described with reference to FIGS. 20 to 23, the time required to measure the data of the predetermined characteristic portion becomes too long. However, it is difficult to accurately reproduce the model because of measurement error and measurement omission.

Further, even when another method is used,
Generally, the data obtained by a three-dimensional measuring device is C
Compared with the data generated by AD, it contains a lot of errors and is composed of point cloud data, so much information is missing. Therefore, in order to obtain a desired free-form surface, it is indispensable to perform processing such as correction, interpolation and additional change on the generated free-form surface. It is difficult to perform these processes because data that can be processed cannot be added.

Therefore, in the conventional case, it is difficult to generate a free-form surface having an accurate shape or to arbitrarily modify the free-form surface using predetermined point group data obtained by a three-dimensional measuring device or the like. was there.

The present invention has been made in view of such a situation, and generates a free-form surface of an accurate shape based on predetermined point group data having a relatively small amount of data and is generated. The free-form surface can be arbitrarily modified.

[0015]

A first free-form surface generating apparatus of the present invention forms a triangulation network for dividing point cloud data into a predetermined number of collecting points and dividing group points. Forming means, converting means for converting each side forming the triangular mesh into a curve, generating means for generating a curved surface patch including the curved surface, and the entire curved surface formed by the curved surface patches, characteristic points satisfying a predetermined condition. And a correction means for correcting the curved surface using the feature points, and the conversion means uses the position vector obtained by the pseudonormal line of the vertices of the triangulation network to determine each side of the triangulation network. It is converted to a cubic Bezier curve, and the extraction means uses pseudo-normals of points on the curved surface and triangulation.
The angle between the pseudo-normal vertex, and extracts as a feature point a point which is within a predetermined reference range. Also,
A first free-form surface generating method of the present invention includes a dividing step of dividing point cloud data into a predetermined number of collecting points, and a forming step of forming a triangular mesh with respect to the collecting points divided by the processing of the dividing step. A conversion step of converting each side forming the triangular net into a curve, a generation step of generating a curved surface patch including the curve, and an extraction of extracting feature points satisfying a predetermined condition from the entire curved surface formed by the curved surface patch. And a correction step for correcting the curved surface using the feature points. The conversion step uses the position vector obtained by the pseudo-normal line of the vertices of the triangulation mesh to calculate each side of the triangulation mesh with a cubic Bezier curve. And the extraction step converts the points inside the surface
The angle between the pseudo-vertex normals pseudo normal line triangulation of,
The feature is that points within a predetermined reference range are extracted as feature points.

A second free-form surface generator of the present invention is a point cloud.
Dividing means for dividing the data into a predetermined number of aggregation points, and dividing
Form a triangulation network for the set points divided by means
Forming means and converting each side that makes up the triangulation network into a curve
Conversion means and generation means for generating a curved surface patch including a curve
From the entire curved surface composed of curved surface patches,
The extraction means that extracts the feature points that satisfy the condition
And a conversion means for correcting the curved surface using the conversion means,
Position vector obtained by pseudo-normal of vertices of triangulation
Convert each side of the triangulation into a cubic Bezier curve using
The output means is the three pseudo normals that the vertices of the triangular mesh have.
The angle between any two pseudo-normals is the predetermined reference value.
The feature points are the points that make up the vertices with a larger angle.
Characterized by issuing. The second free song of the present invention
The surface generation method divides the point cloud data into a predetermined number of set points.
And the collection that was divided by the processing of the division step.
For the confluence points, a forming step for forming a triangular mesh, and a triangle
A conversion step for converting each side of the net into a curve, and a song
A generation step to generate a surface patch containing lines, and a surface pattern
The entire curved surface formed by the switch
Using the extraction step to extract the feature points to add and the feature points
And a conversion step for correcting the curved surface,
Is the position vector obtained by the pseudo-normal of the vertices of the triangular mesh.
Convert each side of the triangulation into a cubic Bezier curve using Tor
Then, the extraction step is performed by using three pseudo
Of the normals, the angle between any two pseudo-normals is
Feature points are the points that make up the vertices whose angle is greater than the reference value.
It is characterized by extracting as.

In the first free-form surface generating apparatus and method of the present invention, the dividing means divides the point cloud data into a predetermined number of collecting points, and the forming means forms a triangular mesh for the divided collecting points. The converting means converts each side forming the triangular net into a curve, the generating means generates a curved surface patch including the curve, and the extracting means determines a predetermined surface from the entire curved surface formed by the curved surface patch. The characteristic points that satisfy the conditions are extracted, the correcting means corrects the curved surface using the characteristic points, and the converting means uses the position vector obtained by the pseudonormal line of the vertices of the triangular mesh to calculate each of the triangular meshes. The side is converted into a cubic Bezier curve, and the extraction means uses a pseudo-normal line and a triangle of a point in the curved surface.
The angle between the pseudo-vertex normals network extracts a point which is within a predetermined reference range as a characteristic point.

A second free-form surface generating apparatus and method according to the present invention
The method is that the dividing means divides the point cloud data into a predetermined number of aggregate points.
The dividing and forming means divides the set points into triangular meshes.
And the transforming means transforms each side of the triangulation into a curve.
The conversion means generates a surface patch including a curve,
If the extraction means is a whole surface composed of surface patches,
Then, the feature points that satisfy the predetermined condition are extracted, and the correction means
The curved surface is modified using the feature points, and the conversion step is
The position vector obtained by the pseudo normal of the vertex of the square mesh is
Convert each side of the triangulation into a cubic Bezier curve using
The step consists of three pseudo normals that the vertices of the triangulation have.
The angle between any two pseudo-normals is the predetermined reference value.
The feature points are the points that make up the vertices with a larger angle.
Put out.

[0019]

1 is a block diagram showing the configuration of an embodiment of a CAD / CAM system 1 using a free curve generation device 12 of the present invention.

The three-dimensional measuring device 11 measures a spatial shape of a model having a predetermined shape (acquires shape data from a mock) according to a command supplied from the outside,
Predetermined point cloud data corresponding to the shape is generated and supplied to the free-form surface generating device 12.

By operating the input device 13 composed of an input device such as a keyboard and a mouse, the user can instruct the free-form surface generating device 12 to perform various operations corresponding to a predetermined operation. Has been done.

The free-form surface generating device 12 corresponds to a predetermined shape in the virtual space based on the point cloud data input from the three-dimensional measuring device 11 according to a user's instruction input via the input device 13. A free-form surface and a modified free-form surface are generated and displayed on the display device 14.
Therefore, the user performs desired correction processing while referring to the free-form surface displayed on the display device 14
You can tell 2. In addition, the free-form surface generator 1
2 is adapted to supply the generated free curved surface data to the tool path creating device 15 in response to an instruction from the user.

The tool path creating device 15 creates data for cutting that defines the tool driving path on the offset polygon based on the free curved surface data from the free curved surface creating device 12, and records it on the floppy disk 16. It is done like this. The NC milling machine 17 installed in the machining center uses the cutting data recorded on the floppy disk 16 to drive the NC milling machine included in the NC milling machine 17 to drive the gold of a predetermined product corresponding to the cutting data. It is designed to generate types. The data may be directly supplied from the tool path creating device 15 to the NC milling machine 17 without passing through the floppy disk 16.

Next, the processing operation of the CAD / CAM system 1 will be described with reference to the flowchart of FIG.

Now, the point cloud data corresponding to the shape of a predetermined object (model) is input to the free-form surface generating device 12 from the three-dimensional measuring device 11, and the user operates the input device 13 to perform a predetermined operation. It is assumed that the generation device 12 is instructed to generate a free-form surface corresponding to the point cloud data.

In step S1 (dividing means) of FIG. 2, the free-form surface generating device 12 responds to an instruction from the user by a predetermined number of in-phases spatially located close to the point cloud data. The points (for example, points forming the same plane of the object) are grouped to generate a set point. That is, in this step, the point cloud data is divided into a plurality of set points composed of a predetermined number of points. Specifically, the acquired point cloud data is divided into data for each basic surface of the model.

In the following step S2 (formation means), the free-form surface generating device 12 forms a triangular mesh with respect to the points forming the set points. Here, the triangular mesh formed in this step will be described with reference to FIG.

As shown in FIG. 3, the free-form surface generator 12
In the virtual space (three-dimensional space) in the
The points (one group of points) forming one set point are spatially arranged at predetermined positions. In the triangular mesh generation method of step S2, these three-dimensional points are projected onto a predetermined plane (the xy plane in the figure), and the projected points are Delaunay's triangular mesh (the circumscribing of three points). A combination of three points is determined so as to form a triangulation network composed of three points selected so that no other points exist in the circle. Then, by applying the combination on the plane to the points on the space, a triangular network on the space (three-dimensional) is formed. In this way, a triangular mesh is formed with respect to a predetermined set point.

In the subsequent step S3, it is determined whether or not the triangular mesh has been formed for all the groups. When it is determined that the triangular mesh is not formed for all the groups, the process returns to step S1 and the subsequent processes are repeatedly executed.

In this way, the processes shown in steps S1 to S3 are repeatedly executed, and a triangular mesh is formed for all the groups forming the free-form surface (for example, each group corresponding to the six faces of the model). At this time, a YES determination is made in step S3, and the process branches to step S4.

In step S4, the free-form surface generator 12
Composes the groups in which the triangular mesh is formed according to a predetermined rule. That is, as a result, data of a three-dimensional shape in which each of the six faces is formed by a triangular mesh is obtained.

In the next step S5, the free-form surface generating device 12 obtains a pseudo normal line corresponding to each point by utilizing a triangulation network. Here, the pseudo normal line of each point obtained in this step will be described with reference to FIG.

As shown in FIG. 4, the point Pi forms a triangular network with the points Pa1 to Pan around it. Each triangle forming this triangulation network can be expressed by equation (1). Tj (Paj, Paj + 1, Pi) (1≤j≤n) (1)

Now, the normal vector [L1] ([] of the triangle T1 (Pa1, Pa2, Pi) formed by the points Pa1, Pa2, Pi)
Represents a vector. Hereinafter, in this specification, a vector is represented by []. Since the normal vector [L1] is a vector perpendicular to the plane defined by the points Pa1, Pa2, and Pi, the vector [PiPa
1] (a vector from the point Pi to the point Pa1. Hereinafter, a vector from a predetermined point to the next point is also described).
It has the direction of the vector represented by the cross product of the vector [PiPa2]. That is, when the normal vector [L1] is the unit vector, the normal vector [L1] can be expressed by the equation (2). [PiPa2] × [PiPa1] / | [PiPa2] × [PiPa1] | (2)

Similarly, the normal vector [Lj] of the triangle Tj (Paj, Paj + 1, Pi) can be expressed by equation (3). [PiPaj + 1] × [PiPaj] / | [PiPaj + 1] × [PiPj] | (3)

Therefore, the pseudo normal vector [Ni] of the point Pi
Is defined as an average vector of these normal vectors [Lj] (1 ≦ j ≦ n) as in Expression (4).

[Equation 1]

In this way, in step S5, the pseudo normal line corresponding to each point is obtained.

In step S6 (conversion means), the free-form surface generating device 12 uses each side of the triangle Tj (Paj, Paj + 1, Pi) by using the pseudonormal line of each point obtained in step S4. Convert to cubic Bezier curve.

The conversion of the cubic Bezier curve executed in step 6 will be described with reference to FIG.

FIG. 5 shows a state in which the side PiPa1 of the triangle T1 (Pa1, Pa2, Pi) is converted into a cubic Bezier curve.

The cubic Bezier curve [P] is defined by four position vectors ([R0] to [R3]) corresponding to the control points.
It can be expressed by Expression (6) using the shift operator E of Expression (5). [Ri + 1] = E [Ri] (i = 0,1,2) (5) [P] = ((1-t + tE) ∧3) [R0] (6)

However, in the case shown in FIG. 5, the position vector is the vector [R0] corresponding to the point Pi.
And only two position vectors of the vector [R3] corresponding to the point Pa1 are given.

Therefore, the remaining two position vectors (vector [R1] and vector [R2]) are obtained using the pseudo normal vector [Ni].

Specifically, in the direction perpendicular to the plane defined by the pseudo normal vector [Ni] and the vector [PiPai] and the plane defined by the pseudo normal vector [Ni], Vector [R1] and vector [R2]
Two control points corresponding to That is, the vector [g] having the above-mentioned direction is obtained by the equation (7). [G] = ([Ni] × [PiPa1]) × [Ni] (7)

Then, the side PiPa in the direction of the vector [g]
Take one control point corresponding to the vector [R1] at the position represented by the length of 1/3 of the side, and set the side Pi in the direction of the vector [g].
The remaining control points corresponding to the vector [R2] are taken at the position represented by the length of 2/3 of Pa1. That is, the position vectors corresponding to these control points (vector [R1]
And the vector [R2] can be expressed by equations (8) and (9). [R1] = [R0] + ([g] / | [g] |) (| [PiPa1] | / 3) (8) [R2] = [R0] + ([g] / | [g] |) (2 | [PiPa1] | / 3) (9)

Although the control point corresponding to the vector [R2] is set in the vector [g] direction, the same processing as that at the point Pi is performed on the point Pa1 and the vector starting from the point Pa1 is used. It is also possible to take the position represented by the length of 1/3 of the side Pa1Pi in the direction.

In this way, the side PiPa1 can be converted into a cubic Bezier curve defined by the four position vectors (vector [R1] to vector [R3]). In addition, other sides and sides of other triangles can be similarly converted.

Next, in step S7 (generation means), the free-form surface generating device 12 generates a cubic Bezier surface patch for one surface surrounded by the cubic Bezier curve. The cubic Bezier curved surface [Q] is obtained by shifting the shift operator E of the equation (10) and the shift operator F of the equation (11) by using 16 position vectors ([A00] to [A33]) corresponding to the control points. Can be expressed by the formula (12). [Ai + 1, j] = E [Ai, j] (i, j = 0,1,2) (10) [Ai, j + 1] = F [Ai, j] (i, j = 0,1 , 2) (11) [Q] = ((1-u + uE) ∧3) (1-v + vF) ∧3) [A00] (0 ≦ u, v ≦ 1) (12)

Generating a cubic Bezier surface is performed by using 16 position vectors (vector [A00] to vector [A3]
3]) is the same as determining. Also, in this case, a cubic Bezier curve corresponding to three sides is known.
Therefore, since 12 (= 4 * 3) control points are known, a cubic Bezier surface patch can be generated by obtaining the remaining four internal control points. The cubic Bezier surface is
It is a curved surface for four vertices, and in this case, it is a curved surface for three vertices, but two of the four vertices are the same point (degenerate), and the same calculation method is used. You can

Therefore, in this step, the normals on the three cubic Bezier curves are obtained by using the pseudo normals of the three vertices. Then, the condition that the normal line on the cubic Bezier curve and the normal line of the edge of the cubic Bezier curved surface (near the cubic Bezier curve) represented by the internal control point match (condition that inner product is 1) The internal control points are determined using a least squares approximation to. For details of this point, see Japanese Patent Application No. 06-
No. 128122.

In this way, by generating cubic Bezier curved surface patches for all triangular networks, a free curved surface corresponding to a given point group is generated, and the image is displayed on the display device 14.

Then, in step S8 (extracting means), points (feature points) satisfying a predetermined condition are extracted.

Here, an example of the feature points extracted in step S8 will be described with reference to FIGS.

6 and 7 show the first embodiment of the conditions for extracting the characteristic points. That is, as shown in FIG. 6, a predetermined spatial extent of the point Pi is determined as a selection range, and among the point groups included in the selection range,
As shown in FIG. 7, the angle θ formed between the pseudo normal [m] of the point and the pseudo normal [Ni] of the point Pi is the angle θ1, θ2 (θ1 <θ2) as the two reference values. Within range (θ1 <θ
Only points that satisfy <θ2) should be extracted. That is, the points having the pseudo normal [m] satisfying the expression (13) are extracted. COS (θ2) <[Ni] ・ [m] / | [Ni] || [m] | <COS (θ1) (13)

FIG. 8 shows a second embodiment of conditions for extracting feature points. That is, as shown in FIG. 6, a selected range is determined, and among the points included in the selected range, the angle θ formed by the pseudo normal [m] of the point and the pseudo normal [Ni] of the point Pi is As shown in FIG. 8, only points larger than a predetermined reference value (angle θ3) (satisfying θ3 <θ) are extracted. That is, the points having the pseudo normal [m] satisfying the expression (14) are extracted. COS (θ3)> [Ni] ・ [m] / | [Ni] || [m] | (14)

FIG. 9 shows an example of a state in which the characteristic points are extracted by applying the predetermined conditions in this way. The user can use the extracted feature point data to generate a new curve or curved surface (for example, by the method disclosed in Japanese Patent Application No. 04-274570) and partially modify the free curved surface. Is. Further, since the feature points can be processed independently of the entire free-form surface, it can be used for various applications.

For example, a free-form surface generated only from point cloud data as shown in FIG. 10 should be divided into a basic curved surface and a characteristic curved surface (for example, a curved surface having a large displacement difference between adjacent patches). Therefore, it is difficult to partially change or modify.

On the other hand, as shown in FIG. 11, when a basic curved surface and a curved surface having a predetermined characteristic (curved surface generated by the characteristic points) are separated from the free curved surface generated only by the point group data, the CAD is performed. Since the shape of each curved surface can be processed separately, the fillet diameter and the shape of the fillet can be easily processed even when performing, for example, fillet processing (processing for smoothly connecting basic curved surfaces having different characteristics). Can be changed.

Returning to the explanation of the flow chart of FIG. 2, in step S9 (correction means), the user rotates, moves, enlarges or reduces the free-form surface displayed on the display device 14, or uses the extracted feature points. Using the generated curve or curved surface, the shape is approximated to the desired shape as described above, and the correction is performed.

Since the image of the free-form surface displayed on the display device 14 is uniquely determined as a predetermined vector function (collection of cubic Bezier surface patches), this free-form surface and an arbitrary plane or A line of intersection with a curved surface is obtained (for example, by the method disclosed in Japanese Patent Application No. 03-118666) (a cross section is obtained), or as shown in FIG. It is also possible to obtain a curve on which there is no point cloud data).
Therefore, the free-form surface can be corrected based on these pieces of information. Further, a curve or a curved surface when an arbitrary curve or curved surface is projected on this free curved surface is obtained (for example, by the method disclosed in Japanese Patent Application No. 05-128216), and correction is performed using this information. You can also

At the subsequent step S10, the user determines whether the free-form surface modified as necessary is the desired one, and when the free-form surface is not the desired one, the step is again made. And the subsequent processing is executed. If the user determines in step S10 that the free-form surface is the desired one, the free-form surface generation processing shown in FIG. 2 ends.

In this way, based on the point cloud data supplied from the three-dimensional measuring device 11, a corresponding free-form surface is generated, and a part of the free-form surface is extracted using the feature points extracted under a predetermined condition. It can be modified to any shape.

A pseudo normal line is defined for each point using only the point cloud data, and from this pseudo normal line, a cubic Bezier curve and 3
Since the next-order Bezier surface patch is generated, a smooth free-form surface can be generated even for random point cloud data having a spatial spread or point cloud data having a relatively small amount of data.

Further, it is possible to extract only useful data or delete unnecessary data from all the point cloud data which is generated by the three-dimensional measuring apparatus 11 and has a relatively short measuring time. , Interpolating the missing data,
A free-form surface can be generated.

In the above embodiment, the pseudo-normal line is used to generate the cubic Bezier curve and the cubic Bezier curved surface patch. However, the curve and the curved surface according to another higher-order Bezier equation are used. You can also do it. The present invention can also be applied to point cloud data (data created by CAD) input by the user.

[0066]

As described above, according to the first free-form surface generating apparatus and method of the present invention, a triangulation network is formed for point cloud data to generate a curve and a surface patch, which is constructed by the surface patch. From the entire curved surface, extract the characteristic points that satisfy the predetermined condition, and use the characteristic points to correct the curved surface.
The characteristic points are converted into cubic Bezier curves for each side of the triangulation network using the position vector obtained by the pseudo-normal line of the vertices of the triangulation network, and the pseudo-normal line of points inside the curved surface and the triangulation network vertex
The angle between the pseudo normal line, since to extract the points that are within a predetermined reference range as a characteristic point, also, according to the second free-form surface generation apparatus and method of the present invention, feature points Using the position vector obtained from the pseudo-normal line of the vertices of the triangulation, each side of the triangulation is converted into a cubic Bezier curve,
Since the angle formed by the normal line and the pseudo normal line is within the predetermined reference range is extracted as a feature point, it is possible to generate a free-form surface corresponding to the point cloud data.
The generated free-form surface can be easily partially modified.

[Brief description of drawings]

FIG. 1 is a CAD using a free-form surface generator 12 of the present invention.
2 is a block diagram showing the configuration of an example of a / CAM system 1. FIG.

FIG. 2 is a flowchart illustrating a processing operation of the CAD / CAM system 1 of FIG.

FIG. 3 is a diagram illustrating a method of generating a triangular mesh in step S2 of FIG.

FIG. 4 is a diagram illustrating a method of obtaining a pseudo normal line in step S4 of FIG.

5 is a diagram illustrating a method of converting each side of the triangular mesh into a cubic Bezier curve in step S5 of FIG.

FIG. 6 is a diagram showing a range of spatial expansion for extracting feature points.

FIG. 7 is a diagram illustrating a condition that a feature point satisfies.

FIG. 8 is a diagram illustrating another condition that a feature point satisfies.

FIG. 9 is a diagram showing extracted feature points.

FIG. 10 is a diagram showing a free-form surface generated only from point cloud data.

FIG. 11 is a diagram showing a free-form surface generated using feature points.

FIG. 12 is a diagram showing that an arbitrary curve on a free-form surface can be extracted from the generated free-form surface.

FIG. 13 is a halftone image displayed on an object display
Is a picture of.

FIG. 14 is an intermediate view of the object shown in FIG. 13 displayed on a display showing the point cloud of which the shape is measured in a grid pattern.
It is a photograph of a toned image .

Based on the point cloud data of FIG. 15 FIG. 14, to produce a free-form surface of the object shown in FIG. 13 to generate a spline curve di
It is a photograph of a halftone image displayed on a spray .

FIG. 16 is a diagram showing data obtained by measuring a cross section of a shape of an object.

17 is a diagram showing a state in which a spline curve is generated based on the data of FIG.

FIG. 18 is a diagram showing a state where a free-form surface of an object is generated based on the data of FIG.

19 is an enlarged view of a part of FIG. 18. FIG.

[20] Di for explaining a method of extracting the feature point of the object
It is a photograph of a halftone image displayed on a spray .

FIG. 21 is an intermediate part of the object shown in FIG. 20, displayed on the display showing the data obtained by measuring the characteristic parts of the shape.
It is a photograph of a toned image .

FIG. 22 is a diagram showing another feature of the shape of the object shown in FIG. 20 on the other display.
It is a photograph of a halftone image .

23 is a table on yet another display showing data obtained by measuring characteristic portions of the shape of the object of FIG. 20.
It is a photograph of the halftone image shown .

[Explanation of symbols]

11 three-dimensional measuring device, 12 free-form surface generator,
13 input device, 14 display device, 15 tool path creating device, 16 floppy disk, 17NC milling machine

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-12473 (JP, A) Shigeru Kuriyama, Trigonal patch using polyhedron, Method of generating curved surface, Journal of Information Processing Society of Japan, Japan, Information Processing Corporation of Japan Society, May 15, 1991, Volume 32, No. 5, 655-664 Hiroyuki Yamamoto, Shinji Uchiyama, Hideyuki Tamura, Delaunay network generation method for 3D modeling, IEICE Transactions, Japan , Institute of Electronics, Information and Communication Engineers, May 25, 1995, J78-D-II, Vol. 5, 745-753 Shinji Uchiyama, Hiroyuki Yamamoto, Hideyuki Tamura, Hierarchical Adaptive Patch Generation from Range Image, Information Processing Society of Japan, Japan, Information Processing Society of Japan, February 15, 1995, Vol. 36, No. 2, 351-361 (58) Fields investigated (Int.Cl. ⁷ , DB name) G06F 17 / 50

Claims (4)

(57) [Claims] 1. A free-form surface generating apparatus for generating a free-form surface corresponding to predetermined point cloud data having a spatial spread, a dividing means for dividing the point cloud data into a predetermined number of set points, and the division. Forming means for forming a triangular mesh with respect to the aggregate points divided by means, converting means for converting each side forming the triangular mesh into a curve, generating means for generating a curved surface patch including the curve, From the entire curved surface composed of curved surface patches, there is provided an extracting means for extracting a characteristic point satisfying a predetermined condition, and a correcting means for correcting the curved surface using the characteristic point, wherein the converting means is the triangular mesh. Using the position vector obtained by the pseudo-normal line of the vertices of
Convert to the next Bezier curve, the extraction means, the pseudo normal line of a point within the curved surface
The angle between the pseudo-normal of the vertex of the triangular network, free-form surface generation apparatus and extracts a point which is within a predetermined reference range as the feature point. 2. A free-form surface generating method for generating a free-form surface corresponding to a predetermined point cloud data having a spatial spread using a computer , wherein the point cloud data is divided into a predetermined number of set points. A step of forming a triangular mesh with respect to the set points divided by the process of the dividing step, a conversion step of converting each side forming the triangular mesh into a curve, and a curved surface patch including the curve. A generating step of generating, an extracting step of extracting a characteristic point satisfying a predetermined condition from the entire curved surface formed by the curved surface patch, and a correcting step of correcting the curved surface using the characteristic point, The converting step converts each side of the triangular mesh into a cubic Bezier curve using the position vector obtained by the pseudo-normal line of the vertices of the triangular mesh, Out step, the angle between the pseudo-vertex normals pseudo normal line <br/> the triangulation points are within said curved surface, and extracts a point is within a predetermined reference range as the characteristic point Free-form surface generation method characterized by. 3. A free-form surface generating device for generating a free-form surface corresponding to predetermined point cloud data having a spatial expansion, a dividing means for dividing the point cloud data into a predetermined number of set points, and the division. Forming means for forming a triangular mesh with respect to the aggregate points divided by means, converting means for converting each side forming the triangular mesh into a curve, generating means for generating a curved surface patch including the curve, From the entire curved surface composed of curved surface patches, there is provided an extracting means for extracting a characteristic point satisfying a predetermined condition, and a correcting means for correcting the curved surface using the characteristic point, wherein the converting means is the triangular mesh. Using the position vector obtained by the pseudo-normal line of the vertices of
Converting to a Bezier curve, the extracting means extracts, from the three pseudo-normals of the vertices of the triangular mesh, the vertices at which the angle formed by any two pseudo-normals is greater than a predetermined reference value. An apparatus for generating a free-form surface, wherein constituent points are extracted as the characteristic points. 4. A free-form surface generating method for generating a free-form surface corresponding to predetermined point cloud data having a spatial spread using a computer , wherein the point cloud data is divided into a predetermined number of set points. A step of forming a triangular mesh with respect to the set points divided by the process of the dividing step, a conversion step of converting each side forming the triangular mesh into a curve, and a curved surface patch including the curve. A generating step of generating, an extracting step of extracting a characteristic point satisfying a predetermined condition from the entire curved surface formed by the curved surface patch, and a correcting step of correcting the curved surface using the characteristic point, The converting step converts each side of the triangular mesh into a cubic Bezier curve using the position vector obtained by the pseudo-normal line of the vertices of the triangular mesh, In the output step, among the three pseudo normals that the vertices of the triangular mesh have, an angle formed by two arbitrary pseudo normals is greater than a predetermined reference value, and the points that form the vertices are the characteristic points. A free-form surface generation method characterized by extracting.