JP2010061259A - Three-dimensional solid shape data conversion device and conversion method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically execute feature extraction, free curved surface setting, and the boundary setting of the feature and the free curved surface in a process for converting three-dimensional bit map data or point group data and STL data into B-reps data whose data capacity is much smaller. <P>SOLUTION: A three-dimensional solid shape data conversion device for converting the shape data of an object into CAD data includes: a region division means for dividing an object into every partial region for polygon data; a display means for three-dimensionally displaying the divided regions; a free curved surface formation means for generating a free curved surface in each of the divided regions; a feature extraction means for extracting a feature from the free curved surface; a phase information creation means for creating phase information between the free curved surface and the feature; an intersection calculation execution means for calculating the intersection of the feature and the free curved surface from the phase information; and a three-dimensional solid shape data configuration means for trimming the feature extracted from the intersection, and for outputting CAD data configured of the extracted feature and the free curved surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a three-dimensional shape data conversion apparatus and method for converting three-dimensional bitmap data, point cloud data, and STL data into three-dimensional CAD data with high operability and usability.

  In order to measure and describe the actual three-dimensional shape as data, a three-dimensional digitizer such as an X-ray CT apparatus, a surface measurement probe, or a laser measuring instrument is used. These devices output bitmap data and point cloud data, which are local cell and point sets. FIG. 4A shows an example of a polygon data image in which the surface shape is represented by a set of minute triangles from these measurement data. Polygon data is described in STL (Standard Triangulation Language), which is one of three-dimensional CAD data formats. This STL data is a set of local information, and does not have global topological information such as a plane or a cylindrical surface of the measurement object. In contrast, a general three-dimensional CAD uses data called “B-reps” (Boundary-representations) having global topological information as shown in FIG. ing. Therefore, an appropriate data conversion technique is indispensable in order to use the measured three-dimensional shape in three-dimensional CAD.

  As a new method for obtaining B-reps data (topological data) having global information by converting bitmap data, point cloud data, and STL data having only local information and no global information 3D display of bitmap data, point cloud data and STL data on the screen, specify a point from the screen to an area expected to have feature information, and search for an area belonging to the same feature from the specified point, A method and apparatus for expanding and extracting global information has been proposed. These methods and apparatuses are disclosed in Patent Document 1 and Patent Document 2.

Japanese Patent Laid-Open No. 2002-230056 JP 2004-046545 A

  In the prior art, when the bitmap data, the point cloud data, and the STL data are three-dimensionally displayed on the screen, and the point is specified from the screen in the area that is expected to have the feature information, the operator sequentially A point was specified from the screen in an area expected to have feature information on the three-dimensional display screen.

  On the other hand, for actual industrial machine parts, the configured features consist of planes, cylinders, cones, and free-form surfaces. For complex machine parts, the number of features can be thousands. There are cases where this is reached. For this reason, the operation method has a problem that the work time is very long and the conversion man-hour is increased.

  In addition, in an area other than the area where the feature can be extracted, the operator has to specify the boundary line of the free curved surface on the three-dimensional display screen from the screen in order to set the free curved surface in the area. Therefore, not only the feature extraction but also the free-form surface setting, there is a problem that the work time becomes very long and the conversion man-hour increases when the operator designates sequentially. In particular, in industrial products such as molds with a small number of machining surfaces and a large number of free-form surfaces, most of the conversion man-hours are spent on setting the boundaries of these free-form surfaces.

  An object of the present invention is to reduce the manual operation of an operator, extract a feature, and form a free-form surface in a process of converting three-dimensional bitmap data, point cloud data, and STL data into B-reps data having a smaller data capacity. It is an object of the present invention to provide a three-dimensional three-dimensional shape data conversion method and apparatus capable of automatically executing setting, boundary setting of a feature and a free-form surface, and shortening an operation time required for conversion.

  The present invention is a three-dimensional three-dimensional shape data conversion device for converting shape data describing a three-dimensional shape of an object into topological data, wherein the entire area of the object is applied to polygon data generated from the shape data. Region dividing means for dividing each of the shape features into partial regions within a certain range, display means for displaying the divided regions three-dimensionally, and free curved surface forming means for generating a free curved surface in each of the divided regions A feature extracting unit that extracts features from the feature amount of the free-form surface and acquires geometric shape definition information; a phase information creation unit that generates phase information from the free-form surface and the feature; and An intersection line calculation execution means for calculating an intersection line with the original free-form surface that could not be extracted, and a feature extracted by the obtained intersection line is trimmed. It characterized in that it comprises a three-dimensional shape data configuration means for outputting to integrate topology data consisting of the free-form surface and tea.

  In addition, a 3D solid shape data conversion method for converting polygon data describing a three-dimensional shape of an object into topological data, wherein the entire region is a shape feature amount with respect to polygon data describing a three-dimensional solid shape Dividing each partial area within a certain range, generating a free curved surface in each divided area, displaying each divided area on a three-dimensional screen, and generating a free curved surface in each divided area The feature is extracted from the feature quantity and the geometric shape definition information is obtained, the intersection line between the extracted feature and the original free-form surface from which the feature could not be extracted, and the obtained intersection line Trimming features; and integrating and outputting topological data composed of extracted features and the generated free-form surface. To.

  According to the present invention, in the process of converting three-dimensional bitmap data, point cloud data, and STL data into B-reps data having a smaller data capacity, the manual operation of the operator is reduced, and feature extraction, free-form surface is performed. Setting, boundary setting of features and free-form surface can be automatically executed, and the operation time required for conversion can be shortened.

  The configuration of the first embodiment of the three-dimensional shape data conversion apparatus according to the present invention is shown in FIG. The three-dimensional solid shape data conversion device C has a function of converting the input point cloud data D1, bitmap data D2 or STL data D3 into B-reps data D0 and outputting it, and the bitmap data / point cloud data / STL data conversion means C1, STL data storage means C2, area division means C3, area division data storage means C4, free curved surface generation means C5, generated free curved surface data storage means C6, feature extraction means C7, extracted feature storage means C8, phase Information creation means C9, phase information storage means C10, intersection line calculation execution means C11, B-reps data construction means C12, generation CAD data storage means C13, STL generation condition specification means C14, area division condition specification means C15, free-form surface generation Condition specifying means C16, input means C17, feature extraction condition specifying means C 8, the phase information generating condition designation means C19, intersection line calculating condition designating means C20, area division correcting means C21, a free curved surface modifying means C22, a display unit C23, features modifying means C24, and a crossing line correcting means C25.

  Bitmap data / point cloud data / STL data conversion means C1, when point cloud data D1 or bitmap data D2 is inputted, is converted from this point cloud data D1 or bitmap data D2 by a polygon generating method such as a marching cube method. STL data is generated and output to the STL data storage means C1. When generating STL data, conditions such as the total number of polygons and allowable errors are input from the STL generation condition specifying means C14. When the STL data D3 is input, the STL data D3 is output to the STL data storage means C2 as it is. The STL data storage means C2 stores the STL data D3 from the bitmap data / point group data / STL data conversion means C1.

  The STL data storage means C2 includes a memory and a hard disk, and has a function of storing input data and outputting it when necessary. The STL data D3 stored in the STL data storage means C2 is data describing a set of minute triangular facets representing the surface of an actual object (actual three-dimensional structure) as shown in FIG.

The area dividing means C3 receives the STL data D3 stored in the STL data storage means C2, and uses the area dividing condition D10 input by the area dividing condition specifying means C15, so that the curvature of the polygon falls within a certain specified condition range. The STL data D3 is divided into regions where polygons belong to the same shape. This region division, first, randomly selecting seed polygon from STL data, finds the vector N ₀ of the seed polygon. Then, if determined the angle .theta.i the normal vector Ni and N ₀ of each polygon around the seed polygon, this .theta.i is, (1) as in equation reduced below the specified threshold angle epsilon _.theta.i is Judge as the same area.

θi <ε _θi (1)
The obtained area division data D4 is stored in the area division data storage means C4. The area division data D4 is three-dimensionally displayed on the PC screen using the display means C23.

  At this time, as shown in FIG. 5, the display color is changed for each divided region. In this display, when the basic information (number of polygons, representative shape features, etc.) for each divided area is displayed on the tree bar in relation to the stereoscopic image and a specific divided area is designated, the area designated by the three-dimensional stereoscopic display is displayed. A close-up display can also be made.

  In this display, as shown in FIG. 6, the original polygon is also displayed overlapping the color display of the divided areas. The area division data storage means C4 includes a memory and a hard disk, and has a function of storing input data and outputting it when necessary. In the area division correction means C21, when an inappropriate area division in the three-dimensional shape expression is found in the area division data D4 displayed on the display means C23, the area division configuration can be corrected from the display means C23.

  In the free curved surface generation means C5, a free curved surface is generated for each divided area using the area division data D4 and the generation condition D11 input by the free curved surface generation condition specifying means C16. The generated free-form surface data D5 obtained is stored in the generated free-form surface data storage means C6. Further, the generated free-form surface data D5 obtained is three-dimensionally displayed on the PC screen using the display means C23. FIG. 7 shows a display example of the generated free-form surface data.

Next, in the feature extraction unit C7, a plane, a cylindrical surface, a conical surface, which is a specific geometric shape, based on the region division data D4, the generated free-form surface data D5, and the feature extraction condition D12 input by the feature extraction condition specifying unit C18. Feature information such as a sphere is extracted. In this feature extraction method, the angle θ _FNif formed between the normal vector FNi of the divided area and the normal vector FNf of the feature set as belonging to the divided area is designated as shown by the equation (2). _When it is below _fn , the divided area is extracted as a feature.

θ _FNif <ε _fn (2)
These geometrical determinations are performed on a parameter space for general use for various feature shapes.

  In this process, a feature is extracted from the divided region where the feature information can be extracted, and the region that does not satisfy the expression (2) for any feature is left as a free-form surface, and the process proceeds to the next step. The extracted feature information D6 is stored in the extracted feature storage means C8. The obtained feature information D6 is three-dimensionally displayed on the PC screen using the display means C23. FIG. 8 shows a display example of feature information.

  In the phase information creation means C9, based on the generated free-form surface data D5, the extracted feature information D6, and the creation condition data D13 input by the phase information creation condition designating means C19, the geometric phase information between the free-form surface and the features. D7 is created. The obtained phase information D7 is stored in the phase information storage means C10. Here, the “phase information” is a relationship representing a connection state (connection relationship, connection state) between each feature and between each free-form surface, and is indispensable information for constructing B-reps data.

  Next, the intersection line calculation execution means C11 extracts using the generated free-form surface data D5, the extracted feature information D6, the phase information D7, and the intersection line calculation condition data D14 input by the intersection line calculation condition designating means C20. The intersection line between the various features and the free-form surface and the intersection line between the extracted features are calculated.

  Using the intersection line obtained by the intersection line calculation execution means C11, the feature surface is trimmed (cut) along the intersection line in the B-reps data construction means C12 (three-dimensional solid shape data construction means) to generate a free-form curved surface And B-reps CAD data D9 is generated. The generated CAD data D9 is stored in the generated CAD data storage means C13. The obtained B-reps CAD data D9 is three-dimensionally displayed on the PC screen using the display means C23. FIG. 9 shows a display example of B-reps CAD data.

  In each step of these conversion processes, the area division correction means C21, the free-form surface correction means C22, the feature correction means C24, and the intersection line correction means C25 are respectively divided into area division data D4 and generated free-form surface data displayed on the display means C23. D5, extracted feature data D6, and intersection line calculation result data D8 can be further corrected from the screen of the display means C23 using a keyboard or a mouse. Each corrected data is fed back again to the area dividing means C3, free curved surface generating means C5, feature extracting means C7, and intersection line calculation executing means C11, respectively, and the area divided data storage means C4 and the generated free curved surface are respectively obtained as new data. The data is stored in the data storage means C5, the extracted feature storage means C8, and the generated CAD data storage means C13.

  Next, the contents of the data conversion processing method performed by the three-dimensional solid shape data conversion apparatus C will be described in detail using specific examples. The processing procedure of the solid shape data conversion method by the three-dimensional solid shape data conversion apparatus C is shown in the flowchart of FIG. Hereinafter, each process will be described with reference to FIGS. 4 to 9 and FIG.

  First, bitmap data, point cloud data, or measurement data in STL format is read (step P1). If the read data is bitmap data or point cloud data, polygon data (STL) is generated (step P2).

  The obtained polygon data (STL) is divided into regions as a whole within a range where the shape feature amount (normal vector) for each polygon falls within a certain range (step P3). FIG. 5 shows an example of three-dimensionally displaying the result of region division for crankshaft measurement data.

  After sufficient area division is obtained, free curved surfaces are generated in all the divided areas (step P6). FIG. 7 shows an example in which free curved surfaces are generated in all the divided regions shown in FIG.

  Next, feature information of the divided area is extracted from the feature quantity of the free curved surface generated in each area and the shape feature quantity for each divided area (step P9). The feature information extracted here is a planar shape, a cylindrical surface shape, a conical surface shape, a spherical shape, and a fillet shape. FIG. 8 shows an example of generating a pre-trim feature shape set in an area in which a feature can be extracted in each divided area shown in FIG.

  Next, phase information between the extracted feature and the remaining free-form surface is created (step P12). Using this phase information, an intersection line (boundary line) between the extracted feature and the remaining free-form surface is calculated (step P13).

  Next, a trim (cutting) operation is performed on the feature generated in P9 based on the obtained intersection line so as to be a CAD plane with the intersection line as a boundary line, and is integrated with the generated free-form surface and output (step P16). . As a result, conversion to B-reps general-purpose CAD data D0 is realized.

  Next, FIG. 3 shows a correction processing procedure of solid shape data conversion in which the results of each process shown in FIG. It shows in the flowchart. Hereinafter, each processing will be described with reference to FIGS. 4 to 9 and FIG.

  First, bitmap data, point cloud data, or measurement data in STL format is read (step P1). If the read data is bitmap data or point cloud data, polygon data (STL) is generated (step P2).

  The obtained polygon data (STL) is divided into regions as a whole within a range where the shape feature amount (normal vector) for each polygon falls within a certain range (step P3). FIG. 5 shows an example of a three-dimensional display of the result of region division for crankshaft measurement data.

  Next, the operator evaluates the result of the area division from the display screen, and determines the suitability of the area division (step P4). In the determination, numerical data representing region division characteristics such as a difference amount distribution from the original measurement data is displayed. If an inappropriate region division has occurred in the determination, the operator corrects the division boundary from the display screen (step P5).

  After sufficient area division is obtained, free curved surfaces are generated in all the divided areas (step P6). Also in this step, the operator evaluates the free curved surface shape generated from the display screen, and determines the validity of the generated free curved surface (step P7). In the determination, numerical data representing a free-form surface characteristic such as a difference amount distribution from the original measurement data is displayed. If an inappropriate free curved surface shape is generated in the determination, the operator corrects the curved surface shape from the display screen (step P8). FIG. 7 shows an example in which free curved surfaces are generated in all the divided regions in FIG.

  Next, feature information of the divided area is extracted from the feature quantity of the free curved surface generated in each area and the shape feature quantity for each divided area (step P9). The feature information extracted here is a planar shape, a cylindrical surface shape, a conical surface shape, a spherical shape, and a fillet shape. Also in this step, the operator evaluates the feature shape extracted from the display screen and determines the validity of the extracted feature (step P10). In the determination, numerical data representing feature shape characteristics such as a difference amount distribution from the original measurement data is displayed. If an inappropriate feature shape is generated in the determination, the operator corrects the feature shape from the display screen (step P11). FIG. 8 shows an example of generating a feature shape before trim that is set in an area where a feature can be extracted in each divided area of FIG.

  Next, phase information between the extracted feature and the remaining free-form surface is created (step P12). Using this phase information, an intersection line (boundary line) between the extracted feature and the remaining free-form surface is calculated (step P13). Here, the operator evaluates the intersection line shape calculated from the display screen, and determines the validity of the intersection line (step P14). In the determination, numerical data representing the intersecting line shape characteristics such as a difference amount distribution from the original measurement data is displayed. If an inappropriate intersection line shape is generated in the determination, the operator corrects the intersection line shape from the display screen (step P15).

  In the above step, when the intersection line between the extracted feature and the adjacent free-form surface cannot be obtained analytically, the boundary line of the feature can be set by projecting the boundary line of the free-form surface onto the feature.

  Next, a trim (cutting) operation is performed on the feature generated in P9 based on the obtained intersection line so as to be a CAD plane with the intersection line as a boundary line, and is integrated with the generated free-form surface and output (step P16). . As a result, conversion to B-reps general-purpose CAD data D0 is realized.

  The above is the data conversion method by the three-dimensional solid shape data conversion apparatus C. An example of B-reps data D0 obtained by this data conversion processing method is shown in FIG. The B-reps data D0 is described by various surface elements such as a plane, a cylindrical surface, a fillet surface, and a free-form surface, and can be used as general-purpose CAD data. In addition, each process of area division, free-form surface generation, feature extraction, phase information creation, intersection line calculation, and B-reps format output can be automatically executed, reducing the number of manual operations by the operator and performing operations necessary for conversion. General-purpose CAD data is obtained by shortening the time. Further, fine correction from the screen can be performed in each process, and high-speed and highly accurate CAD data conversion can be realized.

  According to the present embodiment, in the process of converting three-dimensional bitmap data, point cloud data, and STL data into B-reps data having a smaller data capacity, the manual operation of the operator is reduced as much as possible, feature extraction, It is possible to automatically execute the setting of the free curved surface and the boundary line between the feature and the free curved surface to shorten the operation time required for the conversion.

It is a block diagram which shows embodiment of the solid shape data converter by this invention. It is a flowchart which shows the solid shape data conversion method by the apparatus of FIG. It is a flowchart which shows the correction method of the solid shape data conversion of FIG. It is a schematic diagram which shows the polygon data (STL) based on measurement, and general-purpose CAD data. It is a schematic diagram which shows the three-dimensional display screen which implemented area | region division with respect to the measurement data of the target object. FIG. 6 is a partial enlarged schematic diagram of FIG. 5 showing a divided region and polygon data simultaneously. It is a schematic diagram which shows the three-dimensional display screen which produced | generated the free-form surface in each division area of FIG. It is a schematic diagram which shows the feature extracted from each division area of FIG. It is a schematic diagram which shows the general purpose CAD data converted by the solid shape conversion apparatus.

Explanation of symbols

  C: Three-dimensional solid shape data conversion device, C1: Bitmap data / point cloud data / STL data conversion means, C2: STL data storage means, C3: Area division means, C4: Area division data storage means, C5: Free curved surface Generation means, C6 ... Generation free curved surface data storage means, C7 ... Feature extraction means, C8 ... Extraction feature storage means, C9 ... Phase information creation means, C10 ... Phase information storage means, C11 ... Intersection calculation execution means, C12 ... B -Reps data construction means, C13 ... generated CAD data storage means, C14 ... STL generation condition specifying means, C15 ... area division condition specifying means, C16 ... free-form surface generation condition specifying means, C17 ... input means, C18 ... feature extraction condition specification Means, C19... Phase information creation condition specifying means, C20... Intersection line calculation condition specifying means, C21. , C22 ... free-form surface modification means, C23 ... display means, C24 ... feature correction means, C25 ... the intersection correction means

Claims (10)

A three-dimensional solid shape data conversion device for converting shape data describing a three-dimensional shape of an object into topological data,
Area dividing means for dividing the entire area of the object into polygon data generated from the shape data for each partial area where the shape feature amount falls within a certain range, and display means for displaying the divided areas three-dimensionally A free-form surface generating means for generating a free-form surface in each of the divided areas, a feature-extracting means for extracting a feature from the feature quantity of the free-form surface and acquiring geometric shape definition information, and phase information from the free-form surface and the feature. Trimming a feature extracted by the obtained intersection line, a phase information creation means for generating, an intersection line calculation execution means for calculating an intersection line between the feature and the original free-form surface from which the feature could not be extracted from the phase information And three-dimensional solid shape data constructing means for integrating and outputting topological data composed of the extracted features and the free-form surface. 3-dimensional shape data conversion apparatus.   2. The three-dimensional solid shape data conversion apparatus according to claim 1, wherein the shape data includes bitmap data or point cloud data describing a three-dimensional shape of an object, and polygons are obtained from the bitmap data or point cloud data. A three-dimensional three-dimensional shape data conversion device comprising polygon data conversion means for generating data.   2. The three-dimensional solid shape data conversion apparatus according to claim 1, wherein said region dividing means, free curved surface generating means, feature extracting means, phase information creating means, intersection line calculation executing means, three-dimensional solid shape. A three-dimensional three-dimensional shape data conversion device characterized by comprising storage means for storing the output of data construction means.   2. The three-dimensional solid shape data conversion apparatus according to claim 1, wherein said region dividing means, free curved surface generating means, feature extracting means, phase information creating means, intersection line calculation executing means, three-dimensional solid shape. 3. A three-dimensional three-dimensional shape data conversion apparatus comprising processing condition designating means for setting processing conditions for each of the processing means for data construction means.   3. The three-dimensional solid shape data conversion apparatus according to claim 1 or 2, wherein the display unit displays the three-dimensional data generated by each processing unit, the free-form surface, the feature, and the intersecting line data three-dimensionally. A three-dimensional three-dimensional shape data conversion apparatus comprising correction means for correcting each data from the screen of the means.   3. The three-dimensional solid shape data conversion device according to claim 1, wherein the feature extraction means for extracting features from free surface feature quantities generated in the respective divided regions and acquiring geometric shape definition information includes: It is characterized by having automatic feature extraction means for automatically extracting features by setting input data, and manual feature extraction means for extracting features by designating divided areas to be displayed three-dimensionally on the image plane from the screen. 3D solid shape data conversion device. A three-dimensional solid shape data conversion method for converting polygon data describing a three-dimensional shape of an object into topological data,
A step of dividing the entire region into partial regions whose shape feature amounts fall within a certain range with respect to polygon data describing a three-dimensional solid shape;
Generating a free-form surface in each divided area;
Displaying each divided area on a three-dimensional screen;
Extracting a feature from a feature amount of a free-form surface generated in each divided area and acquiring geometric shape definition information;
Calculating a line of intersection between the extracted feature and the original free-form surface from which the feature could not be extracted;
Trimming the extracted features by the obtained intersection lines;
Integrating and outputting topological data consisting of the extracted features and the generated free-form surface;
A three-dimensional solid shape data conversion method comprising:   The method of converting a three-dimensional solid shape data conversion method according to claim 7, wherein for the polygon data describing the three-dimensional solid shape, the entire region is divided into partial regions whose shape feature amounts fall within a certain range. A three-dimensional solid shape data conversion method characterized by dividing polygon data into regions belonging to the same shape whose curvature falls within a certain range.   8. The three-dimensional solid shape data conversion method according to claim 7, wherein a step of calculating a line of intersection between the extracted feature and an original free-form surface from which the feature could not be extracted and a feature extracted by the obtained line of intersection are obtained. In the trimming step, polygon data displayed in a three-dimensional manner on the image plane, area division, and intersection lines are displayed, and the intersection line between the feature and the original free-form surface is corrected by designation from the screen. 3D solid shape data conversion method.   8. The method of converting a three-dimensional solid shape data according to claim 7, wherein in the step of calculating the intersection line between the extracted feature and the original free-form surface from which the feature could not be extracted, the intersection between the extracted feature and the adjacent free-form surface is performed. A three-dimensional three-dimensional shape data conversion method characterized by setting a boundary line of a feature by projecting the boundary line of a free-form surface onto the feature when the line cannot be obtained analytically.

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