CN102915564A - Oriented bounding box and axial bounding box-based shoe last matching method - Google Patents

Abstract

The invention belongs to the fields such as computer animation, 3D (three dimensional) model building and shape analysis and particularly discloses an oriented bounding box (OBB) and axial bounding box (AABB)-based shoe last matching method. The method comprises the steps of firstly obtaining the OBB of a 3D model foot and a shoe last by matching the foot with the shoe or matching the foot with the shoe last indicating the internal space of the shoe, respectively aligning the foot and the shoe last to three axes of a world coordinative system according to the axial direction of the OBB, computing the AABB of the foot and the shoe last, translating the center of a bottom face quadrangle of the AABB of the foot model to the center of the bottom face quadrangle of the AABB of the shoe last, matching, and properly zooming the shoe if the shoe is larger or smaller. The oriented bounding box (OBB) and axial bounding box (AABB)-based shoe last matching method has the advantages of rapidity, efficacy, capability of accurately zooming the model and providing effective support for a shoe last digital technology.

Description

A kind of pin shoe last or hat block matching process based on oriented bounding box and axial bounding box

Technical field

The present invention relates to the fields such as a kind of computer animation, the foundation of 3D model, shape analysis, specifically refer to a kind of technology such as three-dimensional model coupling, virtual examination footwear that can be used for.

Background technology

Along with developing rapidly of E-commerce market, virtual fitting in the store on the net, virtual examination footwear have become a kind of fashion trend.We can construct different clothes, shoes and human 3d model, with clothes or shoes model through on the manikin, thereby judge whether required commodity suitable.In virtual examination footwear, can come human simulation to wear the state of upper shoes by pin shoe last or hat block matching process, can check and analyze intuitively, expediently the comfort level of footwear.And also can realize exact matching by iteration next-door neighbour point algorithm (ICP) between two similar shoe trees, therefore the research of pin shoe last or hat block Model Matching there is important using value.

The coupling of pin shoe last or hat block model can realize by means of the matching process of general three-dimensional model, and more representational is (1) iteration next-door neighbour point algorithm (ICP).The ICP algorithm mainly comprises corresponding point search and two steps of transformation matrix calculating between model, obtains at last rotation matrix and translation matrix.The method is registration and alignment model effectively, searches complexity but shortcoming is corresponding point, and calculated amount is large.(2) statistic histogram algorithm.The method is easy, is widely used, but can only embodies the overall distribution on three-dimensional model summit, can not effectively weigh local shape.(3) expansion Gaussian image algorithm.This algorithm is the similarity of coming Matching Model by the expansion Gaussian image of three-dimensional model, and the expansion Gauss map is mapped as each grid surface of model a vector of unit ball, and this ball is called Gaussian sphere.The mould length of vector equals the area of grid surface, and the direction of vector equals the normal direction of grid surface.But the expansion Gaussian image of concaver is not only, and the expansion Gaussian image is relevant with the rotation of three-dimensional model coordinate system, and is relatively more responsive to plant noise.(4) Functional Analysis algorithm.The Functional Analysis method is many, the spherical harmonics analysis is arranged, Fourier describes, Zernike square etc., these Functional Analysis algorithms have two shortcomings: (a) general three-dimensional model can not be directly used in Functional Analysis, need carry out parameter sampling, but sampling there is larger restriction to three-dimensional model usually; (b) need unified three-dimensional model coordinate system, the data that three-dimensional model obtains at different coordinate system down-samplings can be different.

Summary of the invention

The present invention proposes a kind of pin shoe last or hat block matching process based on bounding box OBB and bounding box AABB.The method is rotated pin and shoe last model by oriented bounding box OBB first so that they respectively with three axles alignment of world coordinate system; Calculate again their axial bounding box AABB, make the tetragonal center superposition in pin model bounding box tetragonal center, AABB bottom surface and shoe last model bounding box AABB bottom surface; After matching, if shoe last model is bigger than normal or less than normal, according to the range difference of bounding box AABB it is carried out thick convergent-divergent; And the difference method of adjusting the distance improves, and makes the convergent-divergent of shoe last model more accurate.

The present invention is achieved by following technical proposals:

A kind of pin shoe last or hat block matching process based on oriented bounding box and axial bounding box is characterized in that comprising the following steps:

(1) by oriented bounding box pin and shoe last model are rotated first so that they respectively with three axles alignment of world coordinate system;

Specifically: the oriented bounding box OBB that at first obtains pin and shoe last model, described oriented bounding box OBB refers to that three vectors have represented respectively the length of rectangular parallelepiped, wide, high is axial, get that root axle parallel with the pin length direction as the foundation of rotation, calculate first the angle between the X0Z plane of this axial vector and world coordinate system, then with the X-axis rotation of this axle around world coordinate system, make the XOZ plane parallel of this axial vector and world coordinate system; Calculate again the angle between this axial vector and the world coordinate system YOZ plane, then with the Y-axis rotation of this axle around world coordinate system, make the YOZ plane parallel of this axial vector and world coordinate system; Respectively pin and shoe last model are carried out above operation, they are alignd with three axles of world coordinate system respectively;

(2) calculate their axial bounding box AABB, make the tetragonal center superposition in tetragonal center, axial bounding box AABB bottom surface and shoe last model bottom surface of pin model;

Specifically: after pin and shoe last model alignd respectively, ask respectively the axial bounding box AABB of sole plane and OBB baseplane, get tetragonal center, axial bounding box AABB bottom surface as the basic point of translation, tetragonal center, the axial bounding box AABB of pin model bottom surface is moved to tetragonal center, the axial bounding box AABB of shoe tree bottom surface;

(3) match after, if shoe last model is bigger than normal or less than normal, according to the range difference of bounding box it is carried out thick convergent-divergent;

Specifically: pin, shoe last model still with three axles alignment of world coordinate system, utilize the bounding box AABB of pin and the bounding box AABB of shoe tree to compare, at X, on the Z axis, range difference is that two bounding box AABB are respectively at X, maximal value on the Z axis and maximal value poor, minimum value and minimum value poor; If the range difference on X-axis is less than the threshold value (comfort value, this example is got 0.3cm) of setting, then shoe last model is bigger than normal on X-direction, and shoe last model is contracted to the size that range difference equals threshold value in X-direction; If less than given threshold value, then shoe last model is less than normal on X-direction, and shoe last model is amplified to the size that range difference equals threshold value in X-direction at the range difference of X-axis for they; Z axis adopt with X-direction on identical disposal route realization;

(4) difference method of adjusting the distance improves, and makes the convergent-divergent of shoe last model more accurate;

Specifically: on the basis of thick convergent-divergent, calculate the central point of pin model bounding box AABB, three central planes of structure bounding box AABB, for any point on the pin model, a given one length of side makes it at X, Y forms a cube constraint space centered by oneself on the Z axis; Any point for the pin model, if point on the shoe last model is arranged in its solid space, illustrate that this point is the point near shoe last model, calculate respectively the x of these points on the shoe last model in its solid space, y, the z coordinate is fetched into respectively maximum value and the minimal value of three central plane distances again to the distance of three central planes of pin model bounding box AABB; The point of traversal pin model, if the arbitrary coordinate that the point on the pin model arranged is to poor greater than corresponding maximum value and threshold value of the distance of central plane corresponding to pin model bounding box AABB, illustrate that then shoe last model is less than normal on this coordinate axis, calculate respectively this on respective shaft and the distance of the nearest point of shoe last model, be designated as L, traveled through the point of pin model after, the maximal value of getting L, and then add upper threshold value, be exactly that shoe last model needs the range difference that amplifies at this axle; In like manner, if shoe last model is bigger than normal on certain coordinate axis, can correspondingly dwindle.

Beneficial effect: in hyundai electronics commercial affairs more and more flourishing today, can be better purchasing clothing in the ecommerce process, purchase the purchasing process that the footwear behavior more meets reality, more convenient, more easily choose the commodity that are fit to.

Description of drawings

The schematic flow sheet of Fig. 1 implementation procedure of the present invention

Fig. 2 pin model and world coordinate system alignment effect figure

(a) be arbitrary pin model initial configuration

(b) the bounding box OBB of pin model

(c) the pin model is in the rectification on YOZ plane

(d) pin model and effect after world coordinate system aligns

The translation schematic diagram of Fig. 3 pin model

(a) the bounding box AABB of pin model and shoe last model

(b) effect after the pin shoe last or hat block coupling, the right is the shoe tree translucent effect

Schematic diagram after Fig. 4 pin footwear Model Matching

(a) after the pin footwear coupling, pin model part (footwear model part is less than normal) bigger than normal

(b) the bounding box AABB of the translation rear foot and footwear model

The improvement schematic diagram of Fig. 5 footwear scaling of model

(a) black color dots at bounding box center is bounding box AABB central point, and wherein three dimensions is that AABB is on the plane of X-axis mid point, Y-axis mid point, Z axis mid point

(b) three line segments represent that certain point on the footwear minute is clipped to the distance of three central planes of AABB

The experiment effect schematic diagram of Fig. 6 footwear scaling of model

(a) original method zooming effect schematic diagram

(b) the zooming effect schematic diagram of improving one's methods

The effect schematic diagram of Fig. 7 coupling

(a) the effect schematic diagram of man's pin footwear Model Matching trailing flank and back

(b) the effect schematic diagram of each face after the woman sandal coupling

(c) children's pin footwear mate the effect schematic diagram of each face

(d) after the pin model suitably is out of shape, with the matching effect figure of high-heeled shoes.

Embodiment

The below specifies enforcement of the present invention:

Embodiment 1

For pin model and shoe last model, by oriented bounding box OBB rotation, then axial bounding box AABB Pan and Zoom improves four steps to convergent-divergent at last and finishes final coupling first.This paper discussion be pin and shoe tree coupling, but for convenience's sake, experiment effect is the coupling of pin model and footwear model.

(1) alignment of model

For pin or shoe last model, we are rotated by oriented bounding box OBB alignment, reach the purpose of aliging with world coordinate system.OBB (Oriented Bounding Box) is a rectangular parallelepiped of pressing close to object most in essence, and only this rectangular parallelepiped can rotate arbitrarily according to the single order matrix of object.Bounding box OBB is the bounding box information of describing how much nodes, and bounding box OBB is the data that define by three vectors in the method.Structure is as follows:

MCenter represents the centre coordinate of OBB, and mAxes represents three vectors.TVector3 represents to have the structure of three variablees.The calculating key of OBB is to seek optimum orientation, and determines upwards to surround the party minimum dimension of the bounding box of object.For this reason, the calculating key of OBB is to seek optimum orientation, and determines upwards to surround the party minimum dimension of the bounding box of object.For this reason, the method for calculating OBB mainly is to utilize single order and the second-order statistics of apex coordinate, at first calculates the average μ that the summit distributes, and with its center as bounding box, then calculates covariance matrix C _{J, k}Formula is as follows:

$u=\frac{1}{3n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}(q_i+p_i+r_i)---\left(1\right)$

The coordinate vector of the fixed point that formula (1) accumulative total is all calculates average vector μ, and wherein n is the quantity of all triangular facets, q _i, p _iAnd r _iRespectively three summits of i triangular facet.

$C_{\mathrm{jk}}=\frac{1}{3n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}({\stackrel{\→}{p}}_{\mathrm{ij}}{\stackrel{\→}{p}}_{\mathrm{ik}}+{\stackrel{\→}{q}}_{\mathrm{ij}}{\stackrel{\→}{q}}_{\mathrm{ik}}+{\stackrel{\→}{r}}_{\mathrm{ij}}{\stackrel{\→}{r}}_{\mathrm{ik}})1\≤j,k\≤3---\left(2\right)$

Formula (2) utilizes average vector to calculate covariance matrix C _{J, k}, it is 3 * 3 rank matrixes.Wherein

With

It all is tri-vector.Then obtain covariance matrix C _{J, k}Proper vector, determine three of bounding box OBB local coordinate axially.By covariance matrix C _{J, k}Be symmetric matrix, its three proper vectors are mutually orthogonal.After these three proper vector unitizations, set they for three of the local coordinate of object bounding box OBB axially.At last, with all fixed points of object be projected in three axially on, calculate three maximal values on axially, to determine the size of this OBB.

After solving the bounding box OBB of pin model, i.e. three of bounding box OBB axial vectors and central points.We realize the alignment of pin model with that root axle of pin length direction, i.e. that root axle of bounding box among Fig. 2 (b).Calculate the angle between the X0Z plane of this axial vector and world coordinate system, then with the X-axis rotation of this axle around world coordinate system, make the XOZ plane parallel of this axial vector and world coordinate system, shown in Fig. 2 (c):

Calculate the angle on this axial vector and world coordinate system YOZ plane, with the Y-axis rotation of this axle around world coordinate system, make the YOZ plane parallel of this axial vector and world coordinate system, shown in Fig. 2 (d):

Shoe last model in like manner aligns it respectively with three axles of world coordinate system with identical method, it should be noted that the center that the center that needs before above all rotations model move to world coordinate system operates.

(2) translation of model

AABB (AxisAligned BoundingBox) is a rectangular structure, its three axial vectors are parallel to respectively the coordinate axis of world coordinates, so only just can intactly describe a bounding box AABB with the coordinate of a point, AABB is used for the moving to together of pin and shoes pattern herein, and its data structure is as follows:

Max has represented the maximal value of bounding box on coordinate axis, and min has represented the minimum value of bounding box on coordinate axis.The structure of AABB bounding box is very simple, as long as minimum and maximum x value is taken out respectively on all summits of traversal, and the y value, z value (an altogether value), the max point just is comprised of three values of maximum, and the min point is comprised of three values of minimum.

After pin and shoe last model alignd respectively, we can know by Fig. 2 (d), and the sole plane is not parallel with the OBB baseplane, so also need they are asked respectively bounding box AABB.Consider the characteristics of pin and shoe tree, we get bounding box AABB bottom surface quadrilateral, such as the foundation of the tetragonal center among Fig. 3 (a) as translation, tetragonal center, pin model AABB bottom surface is moved to tetragonal center, shoe tree Mode A ABB bottom surface, it should be noted that if shoe last model, then directly translation is if the shoes model, then need to add the height of sole, effect is shown in Fig. 3 (b):

(3) convergent-divergent of model

After two model translations are good, the local situation bigger than normal of pin model occurs sometimes, the pin model namely occurs and partial penetration occurs, shown in Fig. 4 (a), shoes model situation bigger than normal sometimes also can occur.We can be according to (pin, shoe last model still with three axles alignment of world coordinate system) after the model translation, and they are at X, and Y, the range difference on the Z axis dwindle respectively or amplify the footwear model at X, Y, the size on the Z axis.Range difference, the namely distance between certain point coordinate and corresponding certain point coordinate on pin or the shoe tree.At first calculate the range difference between pin model and the shoe last model after the coupling with following process.

After the two model translations, utilize the AABB of pin and the AABB of shoe tree to compare, shown in Fig. 4 (c), at X, on the Z axis, range difference is that two bounding boxs are respectively at X, maximal value on the Z axis and maximal value poor, minimum value and minimum value poor, for example the range difference on the right side of pin is that shoe last model deducts the pin model in the upper maximal value of X-axis in the maximal value of X-axis, the range difference in the left side of pin is that the pin model deducts the minimum value of shoe last model on X-axis in the upper minimum value of X-axis, in like manner can try to achieve the range difference of Z axis pin model front and back.If the range difference on X-axis less than certain threshold value (comfort value, this example is got 0.3cm), illustrates that then shoe last model is bigger than normal on X-direction, shoe last model is contracted to the size that range difference equals threshold value, in like manner Z axis in X-direction; If they less than given threshold value, illustrate then that shoe last model is less than normal on X-direction at the range difference of X-axis, shoe last model is amplified to the size that range difference equals threshold value in X-direction.The method is easier, but the convergent-divergent precision is slightly poor, and can only at X, carry out convergent-divergent on the Z axis.Shown in Fig. 6 (a):

(4) improvement of scaling of model

Because above convergent-divergent degree of accuracy is inadequate, and can not carry out convergent-divergent in Y direction.So make improvements based on the above method.Calculate the central point of pin model AABB, three central planes of structure bounding box are for any point on the pin model, a given one length of side (can control, and numerical value more intensive is larger, and precision is higher by size, the less calculated amount of numerical value is less conversely, precision is poorer, gets a numerical value 1cm of compromise in this example, and pin is long to be 23.80cm), make it at X, Y forms a cube constraint space centered by oneself, shown in Fig. 5 (a) on the Z axis.Any point for the pin model, if point on the shoe last model is arranged in its cube, illustrate that this point is the point near shoe last model, calculate respectively the x of these points (point in its cube on the shoe last model), y, the z coordinate is to the distance of three central planes of pin model AABB, shown in Fig. 5 (b).Be fetched into respectively maximum value and the minimal value of three central plane distances.The point of traversal pin model, if the arbitrary coordinate that the point on the pin model arranged to the distance of central plane corresponding to pin model AABB greater than corresponding maximum value and threshold value (comfort value, this example is got 0.3cm) poor, illustrate that then shoe last model is less than normal on this coordinate axis, calculate respectively this on respective shaft and the distance of the nearest point of shoe last model, be designated as L, after having traveled through the point of pin model, getting the maximal value of L, and then add upper threshold value, is exactly that shoe last model needs the range difference that amplifies at this axle; If arbitrary coordinate of the point on the pin model to the distance of central plane corresponding to AABB less than minimal value and threshold value and, illustrate that then shoe last model is bigger than normal on this axle, calculate respectively this distance from the nearest point of footwear modal distance on respective shaft, be designated as L', traveled through after the point on the pin, getting the minimum value of L', and then deduct certain threshold value, is exactly that shoe last model needs the range difference that dwindles at this axle.The method calculation of complex, but precision is higher, and can be at three direction of principal axis difference convergent-divergents.Shown in Fig. 6 (b):

The experimental result of shoe last model convergent-divergent as shown in Figure 6, Fig. 6 (a), Fig. 6 (b) two figure are the zooming effect of high-heeled shoes model, by Fig. 6 (a), Fig. 6 (b) two figure more as can be known, the width value of high-heeled shoes is larger than the width value of the middle high-heeled shoes of Fig. 6 (b) among Fig. 6 (a), and the high-heeled shoes width is 9.52cm among Fig. 6 (a), and the high-heeled shoes width is 9.39cm among Fig. 6 (b).Result's confirmation, the Innovative method effect is really more accurate than original method.

The structure example

We use Visual C++6.0 and OpenGL shape library at the Intel of 2.40GHz (R) Core2, realized this paper algorithm on the PC of 2GB internal memory, and different 3D models are carried out pin shoe last or hat block Matching Experiment, and the result as shown in Figure 7.Fig. 7 (a) is man's the translucent matching effect of pin footwear, and the left side is the effect of outer instep one side, and the centre is the effect of pin back, and the right is the effect of interior instep one side.Fig. 7 (b), Fig. 7 (c) is respectively the pin footwear coupling of woman sandal and children's pin footwear matching effect, Far Left is the matching effect of pin front, the centre keeps left and is the effect of outer instep or interior instep (the interior instep of Fig. 7 (b) outer instep figure Fig. 7 (c)) side, keep right and be that the effect of pin back, rightmost are the matching effect of interior instep or outer instep (the outer instep of interior instep Fig. 7 of Fig. 7 (b) (c)) side in the centre.This method also is applicable to the pin shoe last or hat block coupling of high-heeled shoes, but need the pin model is done suitable distortion before the coupling, matching effect behind the pin model deformation is shown in Fig. 7 (d), Far Left is the matching effect of pin front, the centre keeps left and is the effect of outer instep one side, keep right and be that the effect of pin back, rightmost are the matching effect of interior instep one side in the centre.

Experimental result shows, the method is quick, and effectively, the bounding box OBB of proposition and bounding box AABB be the alignment of implementation model (rotation) and translation well, and the improved method of asking range difference is the convergent-divergent of implementation model more accurately.For the shoe tree digitizing technique provides effective support.

Claims (1)

1. the pin shoe last or hat block matching process based on oriented bounding box and axial bounding box is characterized in that comprising the following steps:

(1) by oriented bounding box pin and shoe last model are rotated first so that they respectively with three axles alignment of world coordinate system;

Specifically: the oriented bounding box OBB that at first obtains pin and shoe last model, described oriented bounding box OBB refers to that three vectors have represented respectively the length of rectangular parallelepiped, wide, high is axial, get that root axle parallel with the pin length direction as the foundation of rotation, calculate first the angle between the X0Z plane of this axial vector and world coordinate system, then with the X-axis rotation of this axle around world coordinate system, make the XOZ plane parallel of this axial vector and world coordinate system; Calculate again the angle between this axial vector and the world coordinate system YOZ plane, then with the Y-axis rotation of this axle around world coordinate system, make the YOZ plane parallel of this axial vector and world coordinate system; Respectively pin and shoe last model are carried out above operation, they are alignd with three axles of world coordinate system respectively;

(2) calculate their axial bounding box AABB, make the tetragonal center superposition in tetragonal center, axial bounding box AABB bottom surface and shoe last model bottom surface of pin model;

Specifically: after pin and shoe last model alignd respectively, ask respectively the axial bounding box AABB of sole plane and OBB baseplane, get tetragonal center, axial bounding box AABB bottom surface as the basic point of translation, tetragonal center, the axial bounding box AABB of pin model bottom surface is moved to tetragonal center, the axial bounding box AABB of shoe tree bottom surface;

(3) match after, if shoe last model is bigger than normal or less than normal, according to the range difference of bounding box it is carried out thick convergent-divergent;

Specifically: pin, shoe last model still with three axles alignment of world coordinate system, utilize the bounding box AABB of pin and the bounding box AABB of shoe tree to compare, at X, on the Z axis, range difference is that two bounding box AABB are respectively at X, maximal value on the Z axis and maximal value poor, minimum value and minimum value poor; If the range difference on X-axis is less than the threshold value (comfort value, this example is got 0.3cm) of setting, then shoe last model is bigger than normal on X-direction, and shoe last model is contracted to the size that range difference equals threshold value in X-direction; If less than given threshold value, then shoe last model is less than normal on X-direction, and shoe last model is amplified to the size that range difference equals threshold value in X-direction at the range difference of X-axis for they; Z axis adopt with X-direction on identical disposal route realization;

(4) difference method of adjusting the distance improves, and makes the convergent-divergent of shoe last model more accurate;

Specifically: on the basis of thick convergent-divergent, calculate the central point of pin model bounding box AABB, three central planes of structure bounding box AABB, for any point on the pin model, a given one length of side makes it at X, Y forms a cube constraint space centered by oneself on the Z axis; Any point for the pin model, if point on the shoe last model is arranged in its solid space, illustrate that this point is the point near shoe last model, calculate respectively the x of these points on the shoe last model in its solid space, y, the z coordinate is fetched into respectively maximum value and the minimal value of three central plane distances again to the distance of three central planes of pin model bounding box AABB; The point of traversal pin model, if the arbitrary coordinate that the point on the pin model arranged is to poor greater than corresponding maximum value and threshold value of the distance of central plane corresponding to pin model bounding box AABB, illustrate that then shoe last model is less than normal on this coordinate axis, calculate respectively this on respective shaft and the distance of the nearest point of shoe last model, be designated as L, traveled through the point of pin model after, the maximal value of getting L, and then add upper threshold value, be exactly that shoe last model needs the range difference that amplifies at this axle; In like manner, if shoe last model is bigger than normal on certain coordinate axis, can correspondingly dwindle.

Images