CN114519226B - Tubular object fairing anti-deformity drawing method suitable for building CAD design software - Google Patents
Tubular object fairing anti-deformity drawing method suitable for building CAD design software Download PDFInfo
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- CN114519226B CN114519226B CN202210134368.1A CN202210134368A CN114519226B CN 114519226 B CN114519226 B CN 114519226B CN 202210134368 A CN202210134368 A CN 202210134368A CN 114519226 B CN114519226 B CN 114519226B
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- 238000005070 sampling Methods 0.000 claims abstract description 40
- 238000005452 bending Methods 0.000 claims abstract description 15
- 238000007781 pre-processing Methods 0.000 claims abstract description 7
- 238000001125 extrusion Methods 0.000 claims description 13
- 230000000694 effects Effects 0.000 claims description 8
- 238000013507 mapping Methods 0.000 claims description 8
- 238000004321 preservation Methods 0.000 claims description 6
- 230000001154 acute effect Effects 0.000 abstract description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T11/00—2D [Two Dimensional] image generation
- G06T11/20—Drawing from basic elements, e.g. lines or circles
- G06T11/203—Drawing of straight lines or curves
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
- G06T17/10—Constructive solid geometry [CSG] using solid primitives, e.g. cylinders, cubes
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
- G06T17/20—Finite element generation, e.g. wire-frame surface description, tesselation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/80—Geometric correction
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- G—PHYSICS
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/14—Pipes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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Abstract
The invention discloses a tubular product fairing anti-deformity drawing algorithm suitable for building CAD design software, relates to the technical field of building design, and in particular relates to a tubular product fairing anti-deformity drawing algorithm suitable for building CAD design software, which comprises the following steps: s1, preprocessing a sampling point; s11, the trace line is represented by P [ n ] by a series of discrete sampling points; s12, judging the bending degree of the sampling points according to the difference degree of the directions of adjacent line segments of the sampling points, converting the bending degree into a bending radius, determining the number of the sampling points according to the chord length of the round corner part, and obtaining a final track line sampling point sequence; s2, fairing treatment; s3, extruding the model. The invention provides a novel tracing-line-based drawing algorithm which can support any cross-sectional shape and ensure surface fairing and correct model under extreme trajectories such as return bend, acute angle and the like.
Description
Technical Field
The invention relates to the technical field of building design, in particular to a tubular product fairing anti-deformity drawing method suitable for building CAD design software.
Background
Building BIM/CAD-like software requires handling of management and drawing of a large number of tubulars, for example: pipe network facilities such as water and electricity are warmed, folding beam parts, steel bars or line illustration and the like, and tubular objects are drawn, so that the following difficulties are mainly encountered at present:
If only a curve is drawn, the performance is insufficient and the effect is poor;
if the accurate model is drawn, the cost of the original geometric information memory and rendering performance is overlarge;
For complex tubular extension tracks, such as sharp folding angles, the problems of incorrect surface fairing and even misshapen of a model are easy to occur.
Disclosure of Invention
In order to achieve the above purpose, the invention is realized by the following technical scheme: a tubular product fairing anti-deformity drawing method suitable for building CAD design software comprises the following steps:
S1, preprocessing a sampling point;
s11, the trace line is represented by P [ n ] by a series of discrete sampling points;
s12, judging the bending degree of the sampling points according to the difference degree of the directions of adjacent line segments of the sampling points, converting the bending degree into a bending radius, determining the number of the sampling points according to the chord length of the round corner part, and obtaining a final track line sampling point sequence;
s2, fairing treatment;
s21, when extruding a tubular model from a track line, giving an upward direction U of the head point of the track line;
S22, according to the position P0 of the first point, the upper direction U and the line segment direction P0-P1, obtaining the tangent plane Q0 of the first point, the origin of Q0 is P0, the normal direction is P0-P1, and the Y direction of the 2D coordinate system on the surface is U;
S23, setting A=Pn-Pn-1B=Pn-Pn+1 at each point P [ n ] behind; x=a+b, y=a×b; obtaining a section Qn, through which Qn passes, with normal direction equal to X X Y;
S24, mapping the upward direction U [ n ] of the upper tangent plane Q [ n-1] to the tangent plane Q [ n ] as the upward direction of 2D on the plane of Q [ n ] to obtain a final middle point tangent plane Q [ n ];
s3, extruding a model;
s31, obtaining a section P [ n ] of each sampling point by a preprocessing step;
S32, generating two side end surfaces of the extrusion model according to the first section and the last section;
s33, generating a corresponding side surface surrounding the extrusion direction by each section in the middle;
s34, maximizing the effect of corner preservation and deformity protection.
Optionally, in step S12, dot (Normalize (P [ n ] -P [ n-1 ]), normalize (P [ n+1] -P [ n ])) is controlled by a linear parameter.
Optionally, if not specified, the step S21 freely selects an upward direction perpendicular to the first line segment.
Optionally, in the step S32, the method further includes the following steps:
S321, setting a cross-sectional shape R, traversing each point Rx on the R, and mapping the Rx to a tangent plane Q n to obtain a mapped point Rp x;
S322, checking which half space of the tangent plane Q [ n-1] Rp [ x ] is in, if it is the positive half space, rp [ x ] =Rp [ x-1];
S323, repeating the steps S321 and S322 until all points on the section R obtain corresponding difference points;
S324, combining the Rp point queue of the previous section and the Rp point queue of the current section into a side triangular patch of the new extrusion model by using a Strip mode.
Optionally, in the step S34, the method further includes the following steps:
s341, replacing the corner surface in the step S322, wherein one side is integrally lost, so that the corner is lost;
S342, a section in the middle of the corner is selected as a fixed section, the sampling point of the section does not pass through the step S322, and the sampling point at the front side can be simultaneously compared with the fixed section in half space, so that the effects of corner preservation and deformity protection are maximized.
The invention provides a tubular object fairing anti-deformity drawing method suitable for building CAD design software, which has the following beneficial effects:
1. the tubular object fairing anti-deformity drawing method suitable for the building CAD design software supports various cross-sectional shapes, and is suitable for various application fields of tubular objects in the building design software.
2. The tubular object fairing anti-deformity drawing method suitable for the building CAD design software provides an innovative method for keeping fairing and preventing model mismatching.
3. The tubular product fairing anti-deformity drawing method suitable for the building CAD design software improves the universality and the display effect of the geometric shape of the tubular product under various track line conditions on the premise of keeping low memory occupation and low calculation cost of a track line extrusion mode.
4. The tubular object fairing anti-deformity drawing method suitable for the building CAD design software provides a novel drawing method which is based on a track line, can support any cross-section shape, and ensures surface fairing and correct model under extreme tracks such as return bend, acute angle and the like.
Drawings
FIG. 1 is a schematic view of the surface fairing of the present invention;
FIG. 2 is a schematic diagram of the body trace of the present invention;
FIG. 3 is a schematic view of a body corner of the present invention;
FIG. 4 is a schematic view of the body interface of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments.
Referring to fig. 1 to 4, the present invention provides a technical solution: a tubular product fairing anti-deformity drawing method suitable for building CAD design software comprises the following steps:
S1, preprocessing a sampling point;
s11, the trace line is represented by P [ n ] by a series of discrete sampling points;
s12, controlling the difference degree of the directions of adjacent line segments of all sampling points by a linear parameter,
Dot (Normalize (Pn-1), normalize (Pn+1-Pn)) for judging the bending degree of the sampling points, converting the bending degree into bending radius, determining the number of the sampling points according to the chord length of the round corner part, and obtaining the final track line sampling point sequence;
s2, fairing treatment;
S21, when the tubular model is extruded from the track line, giving the upper direction U of the head point of the track line, and if not specified, freely selecting an upper direction vertical to the head line segment;
S22, according to the position P0 of the first point, the upper direction U and the line segment direction P0-P1, obtaining the tangent plane S0 of the first point, the origin of S0 is P0, the normal direction is P0-P1, and the Y direction of the 2D coordinate system on the surface is U;
S23, setting A=Pn-Pn-1B=Pn-Pn+1 at each point P [ n ] behind; x=a+b, y=a×b; obtaining a section Qn, through which Qn passes, with normal direction equal to X X Y;
S24, mapping the upward direction U [ n ] of the upper tangent plane Q [ n-1] to the tangent plane Q [ n ] as the upward direction of 2D on the plane of Q [ n ] to obtain a final middle point tangent plane Q [ n ];
s3, extruding a model;
s31, obtaining a section Q [ n ] of each sampling point by a preprocessing step;
S32, generating two side end surfaces of the extrusion model according to the first section and the last section;
S321, setting a cross-sectional shape R, traversing each point Rx on the R, and mapping the Rx to a tangent plane Q n to obtain a mapped point Rp x;
S322, checking which half space of the tangent plane Q [ n-1] Rp [ x ] is in, if it is the positive half space, rp [ x ] =Rp [ x-1];1.
S323, repeating the steps S321 and S322 until all points on the section R obtain corresponding difference points;
S324, combining the Rp point queue of the previous section and the Rp point queue of the current section into a side triangular patch of the new extrusion model by using a Strip mode;
s33, generating a corresponding side surface surrounding the extrusion direction by each section in the middle;
s34, maximizing the effects of corner preservation and deformity protection;
s341, replacing the corner surface in the step S322, wherein one side is integrally lost, so that the corner is lost;
S342, a section in the middle of the corner is selected as a fixed section, the sampling point of the section does not pass through the step S322, and the sampling point at the front side can be simultaneously compared with the fixed section in half space, so that the effects of corner preservation and deformity protection are maximized.
In summary, when the tubular object fairing anti-deformity drawing method suitable for building CAD design software is used, firstly, a track line is represented by a series of discrete sampling points to form P [ n ], then the bending degree of each sampling point is judged according to the difference degree of the directions of adjacent line segments of the sampling points, the bending degree is converted into a bending radius, the number of the sampling points is determined according to the chord length of a round angle part, and a final track line sampling point sequence is obtained; then, when the tubular model is extruded from the track line, the upward direction U of the head point of the track line is given, then, according to the first point position P0, the upward direction U and the line segment directions P0-P1, the tangential plane Q0 of the first point is obtained, the origin of the Q0 is P0, the normal direction is P0-P1, the Y direction of the 2D coordinate system on the plane is U, and each point P n is arranged
A=pn-pn-1b=pn-pn+1; x=a+b, y=a×b; obtaining a tangential plane Qn, passing through the P n, simultaneously making the normal direction equal to X Y, and mapping the upward direction U n of the previous tangential plane Qn-1 to the tangential plane Qn as the upward direction of 2D on the surface of the Qn to obtain a final intermediate point tangential plane Qn; finally, generating two side end surfaces of the extrusion model according to the first section and the last section, generating each section in the middle, generating corresponding side surfaces surrounding the extrusion direction, setting a section shape R, traversing each point Rx on R, mapping the R x to the section Q n to obtain a mapped point Rp x, checking which half space of the section Q n-1 the Rp x is in, if the half space is positive, rp x=Rp x-1, repeating the steps S321 and S322 until all points on the section R are respectively provided with a corresponding difference point, combining the Rp point queue of the last section and the Rp point queue of the current section into a new side triangular patch of the extrusion model by using a Strip mode, and integrally losing one side of the corner surface due to the replacement of the step S322, so that the corner surface itself is lost, and simultaneously, comparing the sampling space of the step S with the half space of the prior section 322 is the same, and the side of the step S is not the same, and the side of the step S is protected from deformity.
The present invention is not limited to the above-mentioned embodiments, and any person skilled in the art, based on the technical solution of the present invention and the inventive concept thereof, can be replaced or changed within the scope of the present invention.
Claims (3)
1. A tubular product fairing anti-deformity drawing method suitable for building CAD design software comprises the following steps:
S1, preprocessing a sampling point;
s11, the trace line is represented by P [ n ] by a series of discrete sampling points;
s12, judging the bending degree of the sampling points according to the difference degree of the directions of adjacent line segments of the sampling points, converting the bending degree into a bending radius, determining the number of the sampling points according to the chord length of the round corner part, and obtaining a final track line sampling point sequence; the position of the point on the track line is P [ n ], and the difference K is dot (Normalize (P [ n ] -P [ n-1 ]), normalize (P [ n+1] -P [ n ]); if K is greater than the threshold t, the periphery of the sampling point is required to be subjected to fairing treatment;
s2, fairing treatment;
s21, when extruding a tubular model from a track line, giving an upward direction U of the head point of the track line;
S22, according to the position P0 of the first point, the upper direction U and the line segment direction P0-P1, obtaining the tangent plane S0 of the first point, the origin of S0 is P0, the normal direction is P0-P1, and the Y direction of the 2D coordinate system on the surface is U;
S23, setting A=Pn-Pn-1B=Pn-Pn+1 at each point P [ n ] behind; x=a+b, y=a×b; obtaining a section Qn, through which Qn passes, with normal direction equal to X X Y;
S24, mapping the upward direction U [ n ] of the upper tangent plane Q [ n-1] to the tangent plane Q [ n ] as the upward direction of 2D on the plane of Q [ n ] to obtain a final middle point tangent plane Q [ n ];
s3, extruding a model;
s31, obtaining a section P [ n ] of each sampling point by a preprocessing step;
S32, generating two side end surfaces of the extrusion model according to the first section and the last section;
S321, setting a cross-sectional shape R, traversing each point Rx on the R, and mapping the Rx to a tangent plane Q n to obtain a mapped point Rp x;
S322, checking which half space of the tangent plane Q [ n-1] Rp [ x ] is in, if it is the positive half space, rp [ x ] =Rp [ x-1];
S323, repeating the steps S321 and S322 until all points on the section R obtain corresponding difference points;
S324, combining the Rp point queue of the previous section and the Rp point queue of the current section into a side triangular patch of the new extrusion model by using a Strip mode;
s33, generating a corresponding side surface surrounding the extrusion direction by each section in the middle;
s34, maximizing the effects of corner preservation and deformity protection;
s341, replacing the corner surface in the step S322, wherein one side is integrally lost, so that the corner is lost;
S342, a section in the middle of the corner is selected as a fixed section, the sampling point of the section does not pass through the step S322, and the sampling point at the front side can be simultaneously compared with the fixed section in half space, so that the effects of corner preservation and deformity protection are maximized.
2. The method for drawing the fairing anti-deformity of the tubular object suitable for building CAD design software according to claim 1, wherein the method comprises the following steps of: in step S12, dot (Normalize (Pn-1), normalize (Pn+1-Pn)) is controlled by a linear parameter.
3. The method for drawing the fairing anti-deformity of the tubular object suitable for building CAD design software according to claim 1, wherein the method comprises the following steps of: if not specified, the step S21 freely selects an upward direction perpendicular to the first line segment.
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| CA2396419C (en) * | 2000-01-06 | 2007-03-20 | Schlumberger Canada Limited | System and method for multi-resolution fairing of non-manifold models |
| US8878848B2 (en) * | 2012-01-20 | 2014-11-04 | Siemens Aktiengesellschaft | Method and device for snapping normals to create fair 3D surfaces from edge curves |
| CN104915511B (en) * | 2015-06-23 | 2018-04-03 | 广船国际有限公司 | A kind of method for fairing of asymmetric ship type |
| WO2019094218A1 (en) * | 2017-11-09 | 2019-05-16 | Desktop Metal, Inc. | Growth-based design system |
| CN108717725A (en) * | 2018-04-26 | 2018-10-30 | 东华大学 | A kind of spherical joints close-fitting vest undergarment covering the chest and abdomen prototype method based on virtual reality |
| CN110335357B (en) * | 2019-05-23 | 2023-01-24 | 中国自然资源航空物探遥感中心 | Constraint surface multi-resolution control preprocessing method |
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| 基于少量测量数据点的曲面模型重建;佟刚;赵宇明;张国忠;;CAD/CAM与制造业信息化;20060310(Z1);全文 * |
| 基于样图的纹理合成在三维点模型上的实现;曾静;李陶深;;广西大学学报(自然科学版);20101020(05);全文 * |
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