Vector model scanning splicing area processing method and device based on isoparametric line intersection

Abstract

The invention discloses a vector model scanning splicing area processing method and device based on isoparametric line intersection. Traversing the scanning contour and the scanning path in a computer to generate respective preliminary scanning curved surfaces; curved surface extension is performed in the tangential direction to obtain a formed swept curved surface, isoparametric line u-axis coordinate distribution is extracted in a swept splicing area according to a step dichotomy mode, isoparametric lines are extracted for curve intersection to obtain intersection points, and curved surface intersection lines are obtained through fitting; and forming a CAD (Computer Aided Design) scanning model by utilizing the formed scanning curved surface after the curved surface splicing treatment and the geometric degradation operation. The method can enable the computer to quickly, efficiently and accurately generate the model, can control the accuracy of the intersecting line, can be used for solving the problems of long time consumption, failure and the like of complex feature transition processing of scanning modeling in the prior art, reduces the calculation complexity, improves the modeling stability, remarkably improves the calculation processing performance of the computer, and is suitable for popularization and application. The calculation efficiency is improved by several times, and real-time interaction level response is supported.

Description

Technical Field

[0001] The invention relates to the technical field of computer-aided design (CAD), and in particular to a method and device for processing a CAD vector model sweeping and splicing area based on isoparametric line intersection. Background Art

[0002] In computer CAD processing systems, sweeping is an important modeling method, in which the processing of transition areas is the most challenging part. Traditional sweep transition processing uses the method of "surface intersection + intersection line interruption and segmentation". Due to the problems of complex calculation and unstable results in surface intersection, there are many challenges in engineering applications of sweep modeling, such as the time required for complex sweep feature processing may reach minutes, the algorithm may fail completely in some special cases, and the accuracy of the results is difficult to guarantee.

[0003] For example, in general, the process of conventional sweep modeling systems such as the OCCT method is: calculate the swept surface, obtain the swept topology edge, and assemble the swept topology model, where the swept topology edge includes the swept edge along the sweep path, the swept contour, and the intersection line at the swept joint. The method for generating the intersection line at the joint is usually to find the surface intersection. The surface intersection has problems such as unstable calculation results and complicated process.

[0004] Currently, the existing technology has not yet proposed an effective solution to the above problem scenarios. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention proposes a CAD vector model sweeping and splicing area processing method and equipment based on isoparametric line intersection, which realizes intersection dimensionality reduction processing by converting the complex surface intersection problem into a simplified line-line intersection problem, thereby significantly improving the efficiency of computer processing and numerical stability.

[0006] The technical solution adopted by the present invention is: 1. A method for processing a CAD vector model sweeping and splicing area based on isoparametric line intersection, the method steps are as follows: The first step is to generate the swept surface Traversing the sweep profile and the sweep path in a computer, generating a respective preliminary sweep surface along each path curve in the sweep path according to a sweep profile; The swept joint area is a transition area between two swept curved surfaces formed by sweeping the contour shape curve along two adjacent path curves in the swept path.

[0007] The isoparametric lines are three-dimensional curves along the path curve on the swept surface.

[0008] Step 2: Extend the swept surface For each preliminary swept surface, the surface is extended along the tangential direction of the two ends of its own path curve to obtain a formed swept surface; at this time, the formed swept surfaces generated by every two adjacent path curves intersect, and the area at the intersection is used as the swept splicing area; In the present invention, the u-axis direction is along the sweep profile, and the v-axis direction is along the sweep path.

[0009] The third step is to adaptively extract isoparametric coordinates. At each sweeping joint area, the u-axis position coordinates of the isoparametric lines of the adjacent front and rear swept surfaces are extracted by step binary division; The fourth step is to generate the surface intersection line based on the isoparametric line intersection fitting For each swept joint area, isoparametric lines are established on two adjacent formed swept surfaces using the u-axis position coordinates of the isoparametric lines to intersect the curves, and a series of intersection points are obtained by fitting to obtain the surface intersection lines; Step 5: Sweep boundary processing Each adjacent two swept surfaces are cut and spliced ​​using the surface intersection line, and then each swept surface is checked for geometric degradation and geometric degradation operations are performed. The final swept surfaces constitute a CAD sweep model.

[0010] The sweep profile is a closed loop or non-closed loop profile curve, which can be composed of multiple straight lines / curves connected end to end, and the straight lines / curves have smooth or non-smooth transitions. The sweep path is mainly composed of multiple coplanar different path curves connected end to end in sequence. Each path curve is coplanar.

[0011] The third step is specifically as follows: T1, initially the entire sweep profile is used as a curve interval in the u-axis direction; T2. For each u-axis direction curve interval, take the two endpoints and the midpoint of the u-axis direction curve interval along the u-axis direction, establish a connecting line between the two endpoints as the chord length, and calculate the vertical distance from the midpoint to the chord length as the chord height; T3. Determine whether the chord height is within the preset tolerance value and process it: If the chord height is within the preset tolerance (including equal to the preset tolerance), the processing ends; If the chord height is not within the preset tolerance, the current u-axis direction curve interval is subdivided in a binary manner, that is, the original u-axis direction curve interval is further divided into two u-axis direction curve intervals; T4, return to the above step T2, and then repeat T2 to T3 for processing until the chord height of each u-axis direction curve interval is within the preset tolerance; T5. The division distribution of all current u-axis direction curve intervals is used as the isoparametric line distribution, and the coordinate parameters of the dividing points between adjacent u-axis direction curve intervals along the u-axis direction are used as the u-axis direction position coordinates of the isoparametric line.

[0012] Finally, the segmentation is judged and processed based on whether the preset tolerance can be met. If so, the segmentation is stopped; otherwise, the segmentation is continued.

[0013] The fourth step is specifically as follows: S1, establishing isoparametric lines on two adjacent formed swept surfaces according to the u-axis direction position coordinates of all isoparametric lines of the formed swept surface obtained in the third step, taking two isoparametric lines on adjacent formed swept surfaces with the same u-axis direction position coordinates as two adjacent isoparametric lines, and obtaining the intersection point between the two adjacent isoparametric lines; S2. Perform the following judgment process on the number of intersection points: If there is only one intersection point, the intersection point is retained as a legal intersection point; If there are at least two intersection points, the best intersection point is selected based on the tangent vector combined with the three-dimensional position; S3. Use a spline curve fitting algorithm to fit all intersection points to obtain a new fitting intersection line, and use the fitting intersection line as the surface intersection line between the two formed swept surfaces.

[0014] The optimal intersection point is selected by processing the tangent vector in combination with the three-dimensional position, specifically: S21, extract the path tangent vector v of the two path curves corresponding to the two adjacent isoparms at the connection point c1 and v c2 , tangent the two paths to the vector v c1 and v c2 Perform cross product to obtain the first reference normal N1; S22, traverse each intersection point between two adjacent isoparametric lines, and extract the intersection tangent vector v of the two adjacent isoparametric lines at each intersection point 1 and v 2 , the tangent vector v of the two intersection points 1 and v 2 Perform cross product to obtain the second reference normal N2; S23, retaining the same intersection point of the first reference normal N1 and the second reference normal N2; S24, finally, the following judgment and processing are performed: If the number of retained intersection points is one, then this intersection point is the optimal intersection point; If there are multiple intersection points to be retained, the intersection point that is closest in three dimensions to the connection point between two path curves corresponding to two adjacent isoparametric lines is taken as the optimal intersection point.

[0015] The computer is a personal computer, FPGA, single-chip microcomputer, etc.

[0016] 2. A computer device comprising a memory and a processor, wherein the memory stores a computer program, and wherein the processor implements the steps of the above method when executing the computer program.

[0017] 3. A computer-readable storage medium having a computer program stored thereon, characterized in that the computer program implements the steps of the above method when executed by a processor.

[0018] The goal of the present invention is to perform optimization processing on the swept splicing area, optimize the transition connection between the two swept surfaces, obtain the accurate isoparametric intersection line between the two swept surfaces in three dimensions, and then use it for modeling processing of the transition area, making the model processing more efficient and accurate.

[0019] The beneficial effects of the present invention are: The present invention is a solution for rapidly generating a CAD sweep model based on a sweep profile and a sweep path, which enables a computer to generate a model rapidly, efficiently and accurately, and can be used to solve the problems of time-consuming and failure-prone transition processing of complex features in sweep modeling in the prior art.

[0020] The present invention innovatively performs surface isoparametric line intersection processing, converts the intersection line processing of the swept splicing area from surface-to-surface intersection to line-to-line intersection, reduces calculation complexity and improves modeling stability.

[0021] Compared with the sweep modeling algorithm of the open source geometry library OCCT, the present invention can significantly improve the performance of computer computing and processing in complex surface scenes, increase computing efficiency by several times, and support real-time interactive level response.

[0022] At the same time, the present invention can establish isoparametric lines by binary subdivision, and can quickly and effectively control the accuracy of intersection lines by presetting tolerances, thereby meeting engineering accuracy requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the overall flow chart of the method of the present invention; Figure 2 It is a schematic diagram of the circular sweep profile sweeping along two circular arc path curves in the example; Figure 3 A schematic diagram of a swept surface generated by sweeping a circular contour shape curve along an arc path curve in an example; Figure 4 This is a schematic diagram of the result of extending the swept surface along the tangent direction of the path curve endpoint; Figure 5 Schematic diagram of two binary subdivision iterations for isoparametric line density control for the example; Figure 6 The example sweep result and the schematic diagram of the extracted isoparametric lines are shown; Figure 7 The following is a schematic diagram of a closed sweep profile and a closed sweep path for an example; Figure 8 Schematic diagram for example isoparametric intersection-multiple intersection point selection; Fig. 9 The schematic diagram of the sweep degeneration of the closed sweep profile along the sweep path is shown; Fig.10 Sweep the schematic diagram for the example pipe component; Fig.11 It is a schematic diagram of the sweeping component 1; Fig.12 It is a schematic diagram of the sweeping component 2. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1 As shown, the embodiments of the present invention are as follows: Example 1 is as follows: Step 1: Generate the swept surface.

[0026] Traversing the sweep profile and the sweep path in a computer, generating a respective preliminary sweep surface along each path curve in the sweep path according to the sweep profile; The contour shape curve is swept along a sweep path composed of multiple path curves connected end to end in sequence to form a complete swept surface model. For example, the contour shape curve of an arc along a straight path curve can generate a cylinder, and the contour shape curve of an arc along a path curve of an arc can generate a rotation surface. Figure 2 As shown, the circular sweep profile is swept along two circular arc path curves.

[0027] Sweep joint area: When the sweep path contains multiple path curves, the transition area of ​​the swept surface corresponding to the two previous and next path curves.

[0028] Isoparam: In the UV parameter space of the surface, the three-dimensional curve located on the surface is obtained by fixing the parameter v. In the specific implementation, the path curve direction is used as the v parameter direction, and the contour shape curve direction is used as the u parameter direction, thereby forming the UV parameter space of the surface. In the UV parameter space of the surface, the three-dimensional curve located on the surface is obtained by fixing the parameter u as the isoparam. The isoparam lines on the two swept surfaces formed by the sweeping of two adjacent path curves constitute a pair of isoparam lines.

[0029] The input sweep profile P consists of n contour shape curves. Let each contour shape curve be P i (1≤i≤n), the sweep path C consists of m path curves, let each path curve be C j (1≤ j≤m). According to the i-th contour shape curve P i and the jth path curve C j The definition of generates the corresponding swept surface S ij . Traverse all contour shape curves and path curves to generate all swept surfaces.

[0030] like Figure 3 As shown, the swept surface S 11 For example, the swept profile P 1 Along the sweep path C 1 Sweep to obtain the initial swept surface S 11 .

[0031] Step 2: Extend the swept surface.

[0032] The preliminary swept surface generated under each path curve is extended by stretching along the tangential direction of the two ends of its own path curve to obtain a formed swept surface; at this time, the formed swept surfaces generated by every two adjacent path curves intersect, and the area at the intersection is used as the swept splicing area, that is, each swept splicing area has two formed swept surfaces that intersect at two positions, wherein the u-axis direction of the swept surface parameter space corresponds to the swept profile, and the v-axis direction corresponds to the swept path.

[0033] For example, each preliminary swept surface S ij Along the path curve C j The surface is extended in the direction of the end tangent vector to obtain a new swept surface TS ij At this time, there are two formed swept surfaces TS in each swept joint area. ij TS i(j+1) , these two formed swept surfaces have an intersection area, which is the swept joint area. In the surface parameter space UV of each swept surface TS, the contour shape curve P i The direction is the u axis, and the path curve C j The direction is taken as the v-axis.

[0034] like Figure 4 As shown, the initial swept surface S 11 Along C 1 The end point is extended tangentially to obtain the formed swept surface TS 11 , initial swept surface S 12 Along C 2 The starting point is extended in the opposite direction to obtain the formed swept surface TS 12 .

[0035] Step 3: Adaptively extract isoparametric coordinates.

[0036] T1. Initially, the entire sweep profile is taken as a u-axis direction curve interval; the u-axis direction is along the direction of the sweep profile. Then, each u-axis direction curve interval is traversed and processed according to the following process.

[0037] T2. For each u-axis direction curve interval, along the u-axis direction of the swept profile of the formed swept surface, take the two endpoints and the midpoint of the u-axis direction curve interval, where the midpoint is the middle point, establish a line between the two endpoints as the chord length, and calculate the vertical distance from the midpoint to the chord length formed by the two endpoints as the chord height; T3. Determine whether the chord height is within the preset tolerance value and process it: If the chord height is within the preset tolerance and contains equal to the preset tolerance, the current u-axis direction curve interval subdivision processing is terminated; Otherwise, if the chord height is not within the preset tolerance, the current u-axis direction curve interval is subdivided in a binary manner, and then the curve interval is subdivided, that is, the original u-axis direction curve interval is divided into two u-axis direction curve intervals; T4, return to the above step T2, and then repeat T2 to T3 for processing until the chord height of each u-axis direction curve interval is within the preset tolerance; T5. The division distribution of all current u-axis direction curve intervals is used as the isoparametric line distribution to be extracted, and the dividing points between adjacent u-axis direction curve intervals (that is, the coordinate parameters of the two end points of the u-axis direction curve interval along the u-axis direction) are used as the u-axis direction position coordinates of the isoparametric line, which are actually also the discrete points used to obtain the intersection of the curves in the subsequent forming swept surface.

[0038] In a specific implementation, the curve of the sweep profile has two endpoints, and in an actual setting, the two endpoints overlap, so that the curve forms a closed loop.

[0039] In the embodiment, each swept joint area, the formed swept surface TS ij TS i(j+1) The curve interval in the u-axis direction is consistent.

[0040] like Figure 5 As shown, get the endpoint and midpoint of the current u-axis curve interval corresponding to the three-dimensional point p on the swept surface 1 、p 2 、p 3 , calculate point p 3 to p 1 and p 2The chord height distance h between the chord lengths is used to determine whether the chord height h is within the preset tolerance range, such as whether h satisfies h<= 0.001. If not, the current u-axis curve interval is further subdivided into multiple sub-curve intervals, and the above determination is repeated in each sub-curve interval until the chord height h is within the preset tolerance range. After the recursive determination is completed, a series of discrete points of the u-axis curve interval can be obtained, which is the u-axis position coordinate distribution of the isoparametric line.

[0041] Extract the current swept surface TS on the formed swept surface along the discrete points divided in each interval ij TS i(j+1) The isoparametric lines make the swept surface TS ij and forming swept surface TS i(j+1) There are the same number of isoparms.

[0042] The preset tolerance above determines the accuracy of the intersection line of the transition area of ​​the swept feature and is controlled by the user. The smaller the preset tolerance, the higher the accuracy of the surface intersection line.

[0043] Step 4: Generate surface intersection lines based on the intersection fitting of isoparametric lines.

[0044] S1. Establish isoparams on two adjacent forming swept surfaces according to the u-axis position coordinates of all isoparams of the forming swept surface obtained in the third step, and take two isoparams on adjacent forming swept surfaces with the same u-axis position coordinates (adjacent on two forming swept surfaces respectively) as two adjacent isoparams, and find the intersection between the two adjacent isoparams; that is, since the two adjacent path curves are coplanar, there will be an intersection between the two adjacent isoparams, and find the intersection.

[0045] S2. When finding the intersection of curves, there may be one solution or multiple solutions. The number of intersection points to be found is judged and processed.

[0046] From the third step, we can see that in each swept splicing area, the formed swept surface TS ij TS i(j+1) The respective isoparms have been generated. The swept surface TS ij Each isoparm corresponds to the swept surface TS i(j+1) Draw a curve to intersect the isoparametric lines in the image and get one or more intersection points.

[0047] The specific process is as follows: If there is only one intersection point between two adjacent isoparms, the intersection point is retained as a legal intersection point and as a valid intersection point; If there are at least two intersection points between two adjacent isoparametric lines, and if there are multiple intersection points, the best intersection point is selected by processing the tangent vector in combination with the three-dimensional position; S21, extracting the path tangent vectors v of the two path curves corresponding to the two adjacent isoparametric lines at the path connection point by computer calculation c1 and v c2 , tangent the two paths to the vector v c1 and v c2 Perform cross product to obtain the first reference normal N1; S22, traverse each intersection point between two adjacent isoparametric lines, and extract the intersection tangent vector v of the two adjacent isoparametric lines at each intersection point through computer calculation. 1 and v 2 , the tangent vector v of the two intersection points 1 and v 2 Perform cross product to obtain the second reference normal N2; S23, retaining the same intersection point of the first reference normal N1 and the second reference normal N2 as a candidate intersection point; S24, finally, the following judgment and processing are performed on the candidate intersection points: If the number of retained intersection points is one, then this intersection point is the optimal intersection point; If there are multiple intersection points to be retained, the intersection point that is closest in three dimensions to the path connection point between the two path curves corresponding to the two adjacent isoparametric lines is taken as the optimal intersection point.

[0048] Finally, if there are multiple candidate intersection points after screening, the candidate point closest to the connection point of the path curve is selected as the valid intersection point.

[0049] After the overall calculation is completed, a series of intersection points can be obtained. These intersection points are fitted with spline curves to obtain a fitting intersection line. This intersection line is used as the surface intersection line in the transition area of ​​the current sweep feature. Figure 6 shown.

[0050] like Figure 7 As shown, P represents a closed-loop sweep profile, C 1 and C 2 Represent two path curves respectively.

[0051] The swept profile P is along two path curves C 1 and C 2 Perform a sweep.

[0052] like Figure 8 As shown, there are multiple intersection points for isoparametric lines. The contour shape curve P of the eighth sweep contour 8 For example, the path curve C along the swept path 1 , C 2 Generate swept surface and process path curve C 1 To path curve C 2In the transition area of ​​adjacent isoparametric lines IsoCurve 8-1 and IsoCurve 8-2 After the intersection, we get two intersection points IntP 1 、IntP 2 , C 1 , C 2 The tangent directions at the connection are v c1 , v c2 , the corresponding first reference normal N is downward; the tangent direction of the other two intersection points on the two isoparms is v 1-1 , v 2-1 and v 1-2 , v 2-2 , the second reference normal v of the two intersection points on the isoparametric line can be calculated 3-1 Opposite to N, second reference normal v 3-2 In the same direction as N, the corresponding intersection point is IntP 2 .

[0053] S3. Thus, an intersection point is obtained between every two adjacent isoparametric lines. Then, an existing spline curve fitting algorithm is used to fit all the intersection points to obtain a new fitting intersection line. The fitting intersection line is used as the surface intersection line between the two formed swept surfaces for subsequent model generation.

[0054] Step 5: Sweep boundary processing.

[0055] The surface intersection line is used to cut and splice each two adjacent formed swept surfaces, and the boundary of the swept surface and the fitting intersection line obtained in the fourth step are used as the topological edge to construct the topological structure of the swept model.

[0056] Then, each swept surface is checked for any geometric degradation and geometric degradation operations are performed, so that a legal CAD swept model is constructed from the final formed swept surface.

[0057] Check whether there is any geometric degeneration on each swept surface, such as the face degenerating into a line, or the edge degenerating into a point. Specifically, you can delete the topological face and add the topological edge, or delete the topological edge and add the topological point. If so, you need to mark the current edge as a degenerate edge and the current face as a degenerate face to ensure the topology of the CAD swept model is legal.

[0058] like Fig. 9 As shown, the swept profile P 1 Along the swept path C 2 The sweeping result includes two points where the swept edges degenerate and the edges where the swept surfaces degenerate into lines. The current degenerate edges and degenerate surfaces are marked, and the topology is adjusted to ensure the topological legitimacy of the swept model.

[0059] It should be noted that the swept edge corresponding to the v-axis direction of the swept surface may be a curve that degenerates into a point. When there are multiple curves that degenerate into points, there may also be degenerate surfaces.

[0060] Example 2 is as follows: like Fig.10 FIG. 1 is another example of another swept surface and model formed by sweeping a closed-loop swept profile along two S-shaped extended path curves.

[0061] Comparative Example: According to Fig.11 The sweeping member 1 and Fig.12 The sweeping component 2 shown is completely processed by the method of the present invention and the conventional OCCT method, and the results are as follows: Table 1 Comparison of time consumption for sweeping parts OCCT method time consumption (ms) The method of the present invention takes time (ms) Performance improvement times Sweep Part 1 46.5 10.5 3.4 Sweep Part 2 28.7 7.1 3.0 In the above table, the performance improvement multiple is calculated = (OCCT method time consumption - the time consumption of the method of the present invention) / the time consumption of the method of the present invention.

[0062] The isoparametric line intersection method proposed by the present invention reduces the complexity of intersection line calculation from surface to line, thereby improving calculation stability and accuracy.

[0063] The above table lists the processing time (unit: ms) of "Sweep Component 1" and "Sweep Component 2" under the OCCT platform and the method proposed in this invention. It can be seen that "Sweep Component 1" takes 46.5 ms in OCCT, while the method proposed in this invention only takes 10.5 ms; "Sweep Component 2" takes 28.7 ms and 7.1 ms respectively. The results show that the method proposed in this invention can significantly reduce the calculation time in both test scenarios.

[0064] The above specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

[0065] The above description is only a preferred embodiment of the present invention, so all equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A vector model sweeping and splicing area processing method based on isoparametric line intersection, characterized by: The method steps are as follows: The first step is to generate the swept surface Traversing the sweep profile and the sweep path in a computer, generating a respective preliminary sweep surface along each path curve in the sweep path according to a sweep profile; Step 2: Extend the swept surface Extending each preliminary swept surface to form a formed swept surface, and establishing a swept joint area between two adjacent formed swept surfaces; The third step is to adaptively extract isoparametric coordinates. At each sweeping joint area, the u-axis position coordinates of the isoparametric lines of the adjacent front and rear swept surfaces are extracted by step binary division; The fourth step is to generate the surface intersection line based on the isoparametric line intersection fitting For each swept joint area, isoparametric lines are established on two adjacent formed swept surfaces using the u-axis position coordinates of the isoparametric lines to intersect the curves, and a series of intersection points are obtained by fitting to obtain the surface intersection lines; Step 5: Sweep boundary processing The intersection line of the surface is used to cut and splice two adjacent formed swept surfaces, and then each swept surface is checked for geometric degradation and geometric degradation operations are performed. The final formed swept surfaces constitute a CAD swept model.

2. The method for processing vector model sweeping and splicing regions based on isoparametric line intersection according to claim 1, characterized in that: The sweep profile is a contour-shaped curve, and the sweep path is mainly composed of a plurality of coplanar different path curves connected end to end in sequence.

3. The method for processing a vector model sweeping and splicing region based on isoparametric line intersection according to claim 1, characterized in that: The second step is specifically as follows: for each preliminary swept surface, the surface is extended in the tangential direction at both ends of its own path curve to obtain a formed swept surface; when the formed swept surfaces generated by every two adjacent path curves intersect, the area at the intersection is used as the swept splicing area.

4. The method for processing a vector model sweeping and splicing region based on isoparametric line intersection according to claim 1, characterized in that: The third step is specifically as follows: T1, initially the entire sweep profile is used as a curve interval in the u-axis direction; T2. For each u-axis direction curve interval, take the two endpoints and the midpoint of the u-axis direction curve interval along the u-axis direction, establish a connecting line between the two endpoints as the chord length, and calculate the vertical distance from the midpoint to the chord length as the chord height; T3. Determine whether the chord height is within the preset tolerance value and process it: If the chord height is within the preset tolerance, the process ends; If the chord height is not within the preset tolerance, the current u-axis direction curve interval is subdivided in a binary manner, that is, the original u-axis direction curve interval is further divided into two u-axis direction curve intervals; T4, return to the above step T2, and then repeat T2 to T3 for processing until the chord height of each u-axis direction curve interval is within the preset tolerance; T5. The division distribution of all current u-axis direction curve intervals is used as the isoparametric line distribution, and the coordinate parameters of the dividing points between adjacent u-axis direction curve intervals along the u-axis direction are used as the u-axis direction position coordinates of the isoparametric line.

5. The method for processing vector model sweeping and splicing regions based on isoparametric line intersection according to claim 1, characterized in that: The fourth step is specifically as follows: S1, establishing isoparametric lines on two adjacent formed swept surfaces according to the u-axis direction position coordinates of all isoparametric lines of the formed swept surface obtained in the third step, taking two isoparametric lines on adjacent formed swept surfaces with the same u-axis direction position coordinates as two adjacent isoparametric lines, and obtaining the intersection point between the two adjacent isoparametric lines; S2. Perform the following judgment process on the number of intersection points: If there is only one intersection point, the intersection point is retained as a legal intersection point; If there are at least two intersection points, the best intersection point is selected based on the tangent vector combined with the three-dimensional position; S3. Use a spline curve fitting algorithm to fit all intersection points to obtain a new fitting intersection line, and use the fitting intersection line as the surface intersection line between the two formed swept surfaces.

6. The method for processing a vector model sweeping and splicing region based on isoparametric line intersection according to claim 5, characterized in that: The optimal intersection point is selected by processing the tangent vector in combination with the three-dimensional position, specifically: S21, extract the path tangent vector v of the two path curves corresponding to the two adjacent isoparms at the connection point c1 and v c2 , tangent the two paths to the vector v c1 and v c2 Perform cross product to obtain the first reference normal N1; S22, traversing each intersection point between two adjacent isoparametric lines, extracting the intersection tangent vectors v1 and v2 of the two adjacent isoparametric lines at each intersection point, and performing a cross product of the two intersection tangent vectors v1 and v2 to obtain a second reference normal N2; S23, retaining the same intersection point of the first reference normal N1 and the second reference normal N2; S24, finally, the following judgment and processing are performed: If the number of retained intersection points is one, then this intersection point is the optimal intersection point; If there are multiple intersection points to be retained, the intersection point that is closest in three dimensions to the connection point between two path curves corresponding to two adjacent isoparametric lines is taken as the optimal intersection point.

7. The method for processing vector model sweeping and splicing regions based on isoparametric line intersection according to claim 1, characterized in that: The computer is a personal computer, FPGA, single-chip microcomputer, etc.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

Images