CN1895118A - Shoe-tree liftable analog flattening method and system - Google Patents

Abstract

A method for the 3D design and 2D curved surface developing of a shoe last features that the B-Spline is used for expressing the 3D model of a shoe last in 3D laying-out mode the 3D curved surface of a shoe last is divided by quadrangles to realize the transform between 3D and 2D. Its system is also disclosed.

Description

Shoe-tree liftable analog and flattening method and system

1, technical field

The present invention relates to the CAD/CAM technical field, relate in particular to the method that shoe-tree liftable analog and two dimension flatten.

2, background technology

Shoe tree is the parent of shoes, and the shoe tree design is according to the pin type, is beautified with art up processing obtaining threedimensional model.At all kinds of shoes particularly in the leather shoes production process, general directly design from shoe tree, the back threedimensional model is finished in design, by artificial means design is shown laid flat in one and overlaps the shoe pattern, and these shoe patterns can directly drop into batch process.The three-dimensional shoe last and the two-dimentional shoe pattern are the bases of whole design, are the three-dimensional shoe last artificial treatment that this process of the two-dimentional shoe pattern promptly flattens; At footwear industry design field, the shoe designer can see the stereoeffect of corresponding three-dimensional shoe last from the two-dimentional shoe pattern that they design simultaneously, and this designer promptly lies prostrate shoe last or hat block to the process that the two-dimentional shoe pattern is combined into three-dimensional shoe last.The source of traditional two-dimentional shoe pattern mainly contains two kinds: a kind of is to re-pack by hand by the shoe designer, again by scanning, uses vector quantization software, imports computer and handles; Another kind then is to utilize conventional two-dimensional CAD software development to finish.Owing to, all be to utilize graphic design method to finish by these two kinds of shoe patterns that channel obtains, so the shoe pattern of design does not often conform to the actual conditions, need to rely on designer's experience and revise repeatedly just and can put into production, workload is big.Three-dimension curved surface Modeling Technology based on subdivision curved surface, can realize shoe tree two, three-dimensional conversion designs and flattening mutually, make to be converted to automatic realization between the shoe pattern two, the three-dimensional mutually, make the designer that the abundant three dimensional design of freely carrying out be arranged, concentrate one's energy on shoes style and function, to consider.Three-dimensional shoe last model and automatic flattening will bring new design means for footwear industry CAD/CAM.

The flattening of three-dimension curved surface is different with expansion.It is the situation of simulation in external force that curved surface flattens, give two-dimentional curved surface the conversion that three-dimension curved surface is approximate, guarantee three-dimension curved surface and two-dimentional surface area approximately equal, mutual correspondence in boundary line and length keep equating that the position of three dimensional network lattice point and two-dimensional mesh lattice point are corresponding mutually.Two-dimentional curved surface after curved surface launches to require three-dimension curved surface and change is equal fully on shape and size.For the unidirectional curved surface of three-dimensional, can directly launch.Periphery for example, developed surface and former curved surface are equal fully on shape and size; And,,, can only simulate the mode under the external force pressure so can not be unfolded because the surface curvature direction is changeable for surface for multi-direction bending, do approximate flattening.Sphere for example, owing to be the three-dimension curved surface of multi-direction bending, so can only flatten, and can not launch.The planation surface that obtains by flattening and former curved surface are similar and can not equate fully on shape and size.

Shoe tree is an irregular abnormal curved surface by complexity, it also is the three-dimension curved surface of the multi-direction bending of a similar sphere, therefore it is impossible will launching shoe tree fully from the three-dimensional to the two dimension, can only be similar to flattening to the shoe tree surface, and then utilize shoe designer's experience and skill, substantially remain unchanged as dorsal line in the transfer process, beat clip etc. shoe tree is done further flattening in the fold place especially easily at leather, last upper of a shoe can become formal shoe pattern type behind the shoe last or hat block that stretches tight, use in the production.

Three-dimensional modeling and two dimension at shoe tree flatten in the whole design, at first on 3-D view, form three-dimensional female shoe last or hat block curved surface by the curve setting-out, then three-dimension curved surface is carried out the surface subdivision of B-Spline, use a large amount of quadrangles to represent to segment whole curved surface, obtain the three dimensional network lattice point, obtain the two-dimensional mesh lattice point of the two-dimentional shoe pattern of each three dimensional network lattice point correspondence then, mesh point utilizes its correspondence can finish the mutual conversion of shoe tree two dimension, three-dimensional once obtaining again.Test the result factually and show that this method is to meet technological requirement fully.

3, goal of the invention

At present China has nearly 100,000 tame Shoes Factories at present, but does not also have the cover really can practical footwear three dimensional design system, and existing three families of domestic production numerically controlled shoe tree machine producer, the Duo Jia of producer of cutting machine, and present the trend that progressively rises.Fast development along with domestic shoe-making industry, a lot of shoes manufacturing enterprises finish the original accumulation of funds already, beginning is to top grade, the development of automation aspect, demand to high performance numerical control device and software systems is also vigorous day by day, through the cultivation for many years of too much tame manufacturer, formed tens million of market scales.Exploitation high performance three-dimensional design system has become the necessary means of China's shoemaking shoe last or hat block high speed development.

In order to realize above purpose, the present invention proposes a kind of shoe tree three dimensional design and two-dimentional curved surface flattening method based on surface subdivision.Be different from traditional three-dimensional modeling mode, this paper adopts B-Spline to carry out the threedimensional model that the three-dimensional lofting mode is represented shoe tree, for flattening aspect in future, adopts the quadrangle mode to segment whole curved surface simultaneously.This design makes shoe tree 2 d-to-3 d and three-dimensional realize to being converted to of two dimension is unified.And satisfy before and after the conversion, the area approximation of the two-dimentional shoe pattern and the three-dimensional shoe pattern equates that mutual correspondence in boundary line and length keep equating that the position of mesh point is corresponding mutually on the shoe pattern.On the OpenGL platform, realize and provided the effect directly perceived of conversion, verified the exploitativeness of this design.

In order to realize above purpose, the present invention also provides a kind of system of shoe tree design three-dimensional simulation, is used for the discrete point of original three-dimensional input is changed, and expression constitutes the device of curved surface based on the setting-out curve; The present invention also provides a kind of the device that the setting-out curved surface carries out the two dimension flattening has been set up in the front; This device can realize simultaneously setting up the function of the automatic corresponding relation of the three dimensional design and the two-dimentional shoe pattern.

4, technical scheme

Fig. 1 is the basic principle figure of the shoe tree threedimensional model of a kind of surface subdivision of the present invention.As shown in Figure 1, the main thought of this method of system of the present invention is: 1: adopt the curved surface three-dimensional modeling technology based on the setting-out curve, promptly use one group of B-Spline curve to represent three-dimensional last surface.2: then, each B-Spline curve is waited the level segmentation of number.The curve after the level segmentation, form one group of vertical B-Spline curve, more vertical curve is waited the vertical segmentation of number.After vertical segmentation finishes, just can form the three-dimension curved surface of segmentation.Because this subdivision curved surface is the curved surface that a lot of three-dimensional quadrangles are combined into, be easy to just can carry out three-dimensional flattening to two dimension.3: after flattening end, can set up three-dimensional corresponding relation at last to two dimension.The detail operations of each module will be described in detail respectively below.

4.1 the last surface of setting-out curve is represented

The B-SPL has three-dimensional control point to be set P={P _kK=[1..n] } determine, then at P _kThe equation at place is S ^k(x, y, z)=A _k* t ³+ B _k* t ²+ C _k* t ¹+ D 0＜=t (x, y, z)＜P _K+1-P _k(formula 1) uses same equation for the two dimension of three peacekeepings in the future flattens, in this expression and general B-Spline only consider two dimension＜x, y difference, consider three-dimensional point＜x, y, z simultaneously 〉.So S ^kBe that x is arranged, y, three different modes of z.Because these three modes are similarly, in the following discussion, only provide the formula of x direction.

Because three-dimensional manual digital instrument, the point that can well control on the same plane carries out the three-dimensional input.After the user determines a high specific height earlier, use digitizer along the three-dimensional shoe last of physics select some characteristic points to describe at the sustained height profile, so just the set of data points system of being input to of this equal height has been suffered.

Discrete point to input carries out the slotting number of B-Spline, changes and gives smooth curve.[Fig. 2] be four planar points importing after figure after carry out battenization.It should be noted that first point of each height also can be formed a curve, is called the ridge curve in the input data.Other curves in a plane are called surface curve.

4.2 subdivision curved surface

In subdivision curved surface, suppose that the segmentation degree is m, expression is divided into the little straight line of m section to a surface curve; Identical n with the front represents the number at control point; Q represents the number of surface curve altogether.

4.2.1 the level of surface curve segmentation

For the certain surface curve, the height of being had a few all is identical, adopts following segmentation formula.

At first define F ^kExpression S ^kThe section SPL should be divided into little hop count,

Allow $F_k=\left\{\begin{array}{c}m/n(k<n-1)\\ m/n+m\%n(k=n-1)\end{array}\right\}$ (formula 2)

Then formula 1 adopts discrete mode to be expressed as in 4.1 joints:

$S^k=\{S_i^k=A^k*{\left(L^{*}i\right)}^3+B^k*{(L*i)}^2+C^k*(L*i)+D^k,L=(P_{k+1}-P_k,)/F^k,i=[1..F^k\left]\right\}$

(formula 3)

Under this expression, all there is m discrete on the B-Spline curve on each plane, then comprised the breakpoint (control point) of all original SPLs in this m discrete point.Biao Shi advantage is that user's control ratio is more convenient and directly perceived like this.

4.2.2 the vertical segmentation of ridge curve

Use formula 3 to segment too to the ridge curve, allow the ridge curve also disperse and turn to the straightway of m section.

4.2.3 the grid sectionalization of curved surface

After the individual surface curve of all g is all segmented, can obtain g the curve of all representing by m short line segment.M vertical B-Spline curve of definition now, wherein each curve is by g control point.Claim m SPL to form the control curve group of grid G.The same as formula 4 explanation, k bar curve is the starting point formation of getting k section line segment g the input line transect after segmentation among the G.

$G^k=\{G_i^k=S_k^i,k=[1..m],i=[1..g\left]\right\}$ (formula 4)

Below, more every curve among the grid G being carried out the B-Spline interpolation, this has only the curve at g control point this Gk, has also become m the curve that little line segment is formed.Fig. 3 is the figure after Fig. 2 carries out the grid segmentation.

After the point of input is carried out gridding, formed the m bar, every grid by the little straight line combination of m section.Can form (m-1) * (m-1) individual face F combination three-dimensional shoe last curved surface.Wherein each face is made up of four little line segments.Fig. 4 is that Fig. 3 carries out the curved surface demonstration.

$F=\{F_i^k->F_{i+1}^k->F_{i+1}^{k+1}->F_i^{k+1}->F_i^k,k=[1..m-1],i=[i..m-1\left]\right\}$ (formula 5)

4.4.4 the flattening of curved surface

In formula 5, whole last surface is represented the individual little quadrilateral surface for F=(m-1) * (m-1), need below these little three-dimensional quadrilateral surfaces are flattened on the two dimensional surface.Because it is similar and unnecessary equal fully on shape and size that planation surface only needs with former curved surface.But effective for what flatten, before should guaranteeing to flatten and after flattening, the length and the relation of little line segment remain unchanged.

In fact flattening is to carry out according to g bar three-dimensional surface curve.

It is L2 that definition flattens three-dimensional curve L3 curve, and L3 wherein every line is made up of m little line segment, then flattens formula and is

$l^2(x,y)=\{l_i^2=\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}|l_{j+1}^3-l_j^3|,i=[1..m-1\left]\right\}$ (| l _J+1-l _j| the length of expression line segment) (formula 6)

It should be noted that for all g bar surface curves, only carry out the flattening of x direction, and to the ridge curve, the two dimension of only carrying out the y direction flattens.After flattening simultaneously, need adjust the central point of two-dimensional curve.

If the two-dimensional curve that three-dimensional crestal line flattens is J.Utilize formula 6, g bar surface curve is shown laid flat in the bar two-dimensional curve calls the q set, so then have

$q^k\left(x\right)=\{q_{\mathrm{ij}}^k=\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}|S_{j+1}^i-S_j^i|,i=[1..m-1\}$

$q^k\left(y\right)=J_k,$ (k=[1..g|] (formula 7)

By formula 7,, flatten the surface curve set q that is converted to g bar two dimension the surface curve of g bar three-dimensional.Treat the set of q two dimension line, the same method of grid sectionalization of use and " 4.2.3 joint " curved surface can be converted to two-dimentional subdivision curved surface.Design sketch Fig. 6 that Fig. 5 is Fig. 4 after two dimension flattens is at m=100 the time, and the data of Fig. 2 are carried out the design sketch that three-dimension curved surface moulding and curved surface launch.

5 good effects

Adopt above processing, the present invention proposes a kind of shoe tree three dimensional design and two-dimentional curved surface flattening method based on surface subdivision.Be different from traditional three-dimensional modeling mode, this paper adopts B-Spline to carry out the threedimensional model that the three-dimensional lofting mode is represented shoe tree, for flattening aspect in future, adopts the quadrangle mode to segment whole curved surface simultaneously.This design makes shoe tree 2 d-to-3 d and three-dimensional realize to being converted to of two dimension is unified.And satisfy before and after the conversion, the area approximation of the two-dimentional shoe pattern and the three-dimensional shoe pattern equates that mutual correspondence in boundary line and length keep equating that the position of mesh point is corresponding mutually on the shoe pattern.On the OpenGL platform, realize and provided the effect directly perceived of conversion, verified the exploitativeness of this design.

Claims (7)

1. the method for shoe-tree liftable analog and flattening comprises step:

Carry out the three-dimensional lofting mode with SPL and represent that the threedimensional model of last surface adopts the quadrangle mode to segment whole curved surface

Last surface equates to carry out two dimension by area approximation and flattens.

2. method as claimed in claim 1 is characterized in that:

For the certain surface curve, the height of being had a few all is identical, adopt the segmentation formula of equidistant mode, the curve of any one section SPL segmentation multistage short lines combination, guarantee simultaneously, m discrete control point all arranged on the SPL on each plane, and comprised the breakpoint of all original SPLs in the individual point that disperses of this m.

3. method as claimed in claim 1 is characterized in that:

The ridge curve is also segmented by the same mode of claim 2, allow the ridge curve also disperse and turn to the straightway of m section.

4. method as claimed in claim 1 is characterized in that:

Definition g represents the number of vertical direction face, after the SPL of all g face all segmented by the same mode of claim 2, can obtain the curve of the vertical direction that g represents by m short line segment, again every curve in the batten of g bar vertical direction is carried out the equidistant spline interpolation of m, form (m-1) * (m-1) individual face combination three-dimensional shoe last curved surface F, wherein each face is made up of four little line segments.

5. method as claimed in claim 1 is characterized in that:

Being made up of m little line segment when three-dimensional curve, then flattening the mode that three-dimensional curve is a two-dimensional curve, is to guarantee that two-dimensional curve also is made up of m two-dimentional little line segment, and and the length of the three-dimensional little line segment of every little line segment and correspondence be the same.

6. method as claimed in claim 1 is characterized in that:

For all g bar surface curves, carry out the flattening of x direction, and to the ridge curve, the two dimension of carrying out the y direction flattens, and after flattening simultaneously, need adjust the central point of two-dimensional curve.

7. shoe-tree liftable analog and flattening system comprise:

Carry out the device that the three-dimensional lofting mode is represented the threedimensional model of last surface with SPL, it is characterized in that using claim 2, require 3 method;

Adopt the quadrangle mode to segment the device of whole curved surface, be characterised in that the method for using claim 4; Say that last surface equates to carry out the device that two dimension flattens by area approximation.Be characterised in that claim 5,6 the method used.