EP1137349B1 - Method and device for simulating and representing the dressing of a mannequin - Google Patents

Description

Technical field and prior art

The invention relates to the field of simulation of dressing of a manikin, and finds particular application in garment and / or sewing industries.

More and more, garment manufacturers are using databases in which clothing is classified or listed in two dimensions. So we are looking, from the data contained in these bases, to simulate the dressing of a manikin, without have to perform a realization phase on a classic dummy "real".

More specifically, the invention describes a method and a device for setting up, on a virtual manikin, a floating garment originally described by its two-dimensional fabric pieces. The problem is to sew the pieces together in one space three-dimensional (3D) and place the garment thus obtained, around the virtual dummy, in a correct position.

According to a known method, illustrated in FIG. pieces of clothing 2, 4, 6 to be assembled, approximately in front of their final position around a manikin 8. Then, we connect the lines sewing by "elastics" 10, 12, 14, 16, 18, 20, 22. The simulation tissue is then made in "weightlessness". The pieces are move closer to each other and eventually stabilize edge to edge. It only remains to sew.

Simulation of the approximation of parts according to this method takes a lot of time because calculating the physical behavior of a moderately rigid fabric, like cotton, involves the use algorithms for the integration of Euler differential equations, or Runge-Kutta, with a time step significantly lower than the half-period of the lowest sustained oscillation of the differential equation (Exceeding this time step implies an exponential increase errors, and so the fabric explodes).

For a reasonable mesh size of parts (triangles of centimeter size), a surface mass M of about 0.2 kg / m ² , a stiffness k in the warp / weft of about 1000 N / m, one is forced to adopt a no time of 0.1 millisecond. We thus obtain a frequency of about 1kHz ( f = ( k / M / 2π).

Other methods of solving differential equations, said implicit methods, allow to exceed this time step, but the cost of their implementation is greater than the gain obtained, because the non-linearity of the equations and calculations relating to the collisions.

However, a classic garment (a shirt) represents approximately 1.5 m ² of fabric. With an average mesh of 1 cm ² , we obtain a mesh of this garment of about 15000 elements. Each stage of the calculation requires the measurement of the forces applying to each element, and thus at least four measurements of the distance separating it from the neighbors (chain, frame and shears), which, in 3D, represents 12 subtractions, 12 multiplications, and especially 4 square root extractions. It is therefore necessary to make about 60000 square roots, and 180000 multiplications, at least, at each time step.

Curiously, and unfortunately, the addition of viscosities of the order of the critical viscosities obliges to further reduce the step of time. We can not therefore hope to dissipate very quickly the kinetic energy of reconciliation. A very fast approximation speed (due to very stiff elastics) causes wrinkling and stretching, and can also force to reduce the time step. We can not probably not hope to join the pieces in less than 1 second of simulated time, ie 10000 calculation steps. We obtain a total of 1.8 billion multiplications, and 600 million root extractions square. In addition, the collision management time must be added. fabric / fabric and fabric / manikin.

Various optimizations are possible, but the total time of calculation remains impressive (tens of minutes on a microprocessor "pentium 2").

US-5,615,318 discloses a method in which a three-dimensional shape is first achieved by assembling the pieces of clothing. Then sections of a standard model of dummy are dilated until some of these sections dilated areas correspond to sections of the 3D form, and leaving spaces between the manikin and the garment at the level of others sections.

The calculation of the dilation is quite complex. It requires locate corresponding characteristic points on the manikin and on the pieces of each garment, and calculate lengths of arches characteristics passing through some of these characteristic points. The characteristic arches pass for example through the neck, shoulders, or the chest. A dilation factor is deduced for each of these arcs.

The complexity of the calculations and the length of the calculation times also penalize any realization of pieces by cutting in a fabric or material.

Presentation of the invention.

• le dépôt des pièces de vêtement à la surface du mannequin,
• la jonction des pièces de vêtement selon leurs lignes de couture,
• et la relaxation des pièces de vêtement, depuis leur position à la surface du mannequin vers leur position d'équilibre sur le mannequin.

The invention relates to a method for visualizing a garment composed of pieces of clothing on a virtual dummy, or on a representation of a manikin or model of a manikin, or for dressing, with pieces of clothing, a manikin virtual model or manikin model represented in three dimensions, this method comprising:

• the deposit of the pieces of clothing on the surface of the manikin,
• the junction of the pieces of clothing according to their sewing lines,
• and relaxation of the garment pieces, from their position on the surface of the manikin to their equilibrium position on the manikin.

The piece of clothing and the model of manikin can be represented by data stored in a memory of a computer.

According to the invention, the pieces are first "painted" at the surface of the manikin, in a contiguous way, without respecting the geometry or the physical behavior of the tissue. In other words, the parts are pressed against the manikin. For this step, the pieces are deformed continuously, without tearing or intersection.

They are then "sewn", by geometric proximity.

Finally, the compression energy of the fabric is minimized: the fabric is relaxed, or "re-inflated". He goes from a state where this energy of compression is important to a state where it is reduced to a value compatible with the position of the garment on the manikin.

The 3D shape obtained is then ready for the simulation of draped fabric.

The method according to the invention has a computation time reduced compared to methods using tissue simulation for perform the assembly, sewing and donning of the garment, respecting at all times the dimensions and efforts in the fabric.

The invention avoids the preliminary steps of tissue simulation, then bringing the fabric closer to the body or manikin. It avoids in particular the calculations of the physical behavior of the tissue, before assembly. It solves the problems of calculation time, by removing the physical constraints associated with fabric simulation and the approximation of the fabric, and realizing or simulating directly seams (junction of garment parts).

More specifically, the method according to the invention makes it possible to temporarily eschew respect for geometry (respect for lengths, angles of the fabric) to keep only the relations of continuity in topology: it only implements continuous deformations.

Finally, the invention makes it possible to avoid complex calculations of dilation that involve deformity of the manikin: in particular, relaxation involves a deformation of the garment, but not of the dummy.

According to a particular aspect of the invention, the deposit of coins clothing on the surface of the manikin involves the establishment of a point-to-point relationship, or bijective and continuous, between the piece, or a part of that piece, or points representative of such a part, and a corresponding portion of the surface of the manikin, or points such a portion.

This relationship allows you to apply, or flatten, the piece of clothing against the manikin.

• la subdivision de la pièce de vêtement en un premier ensemble de parties,
• la déformation de cet ensemble de parties, en minimisant une fonction d'énergie, qui peut être l'énergie de traction.

The relaxation step can then include:

• the subdivision of the piece of clothing into a first set of parts,
• the deformation of this set of parts, minimizing an energy function, which can be the traction energy.

• la subdivision de la pièce de vêtement en un deuxième ensemble de parties, plus petites que les parties du premier ensemble,
• la déformation de ce deuxième ensemble de parties, en minimisant une fonction d'énergie, qui peut être là encore l'énergie de traction.

It can comprise, in addition:

• the subdivision of the piece of clothing into a second set of parts, smaller than the parts of the first set,
• the deformation of this second set of parts, minimizing an energy function, which can again be the traction energy.

The deformations can be chosen so as to respect the topological relations of the Euclidean volume. The result of this choice is that the calculation of collisions of the fabric becomes useless.

• un déplacement le long de lignes de champ issues du mannequin,
• un déplacement le long de la surface du tissu, dans les autres directions.

Such a deformation may for example comprise:

• a displacement along field lines from the manikin,
• a displacement along the surface of the fabric, in the other directions.

• la visualisation préalable du vêtement sur un mannequin virtuel, selon un procédé tel que décrit ci-dessus,
• la réalisation des pièces du vêtement.

The invention also relates to a method for producing garment parts, comprising:

• the preliminary visualization of the garment on a virtual dummy, according to a method as described above,
• the realization of the pieces of clothing.

The visualization may take place at a place distinct from the place of physical realization of the pieces of clothing, the data on the parts visualized garments being transferred, after visualization or simulation, on the place of realization of the pieces of clothing.

Another subject of the invention is a device for placing implementation of the method according to the invention.

• des moyens de calcul, ou des moyens spécifiquement programmés, pour:

• réaliser le dépôt de la pièce de vêtement sur la surface du mannequin ou sur une surface déduite de celle du mannequin,
• joindre les pièces de vêtement selon leurs lignes de couture,
• réaliser une relaxation des pièces du vêtement, depuis leur position à la surface du mannequin vers leur position d'équilibre sur le mannequin, et
• des moyens pour visualiser le mannequin avec les pièces de vêtement sur le mannequin.

Thus the invention also relates to a device for displaying garment parts on a manikin, comprising:

• computing means, or specifically programmed means, for:

• depositing the piece of clothing on the surface of the manikin or on a surface deduced from that of the manikin,
• join the pieces of clothing according to their sewing lines,
• to achieve a relaxation of the pieces of clothing, from their position on the surface of the manikin to their equilibrium position on the manikin, and
• means for viewing the manikin with the garment parts on the manikin.

In addition, it is possible to preview the selected manikin and / or selected garment parts.

This device may further comprise means for modify a selected piece of clothing or to replace a piece of clothing by another piece of clothing.

• un dispositif de visualisation selon l'invention, tel que ci-dessus,
• des moyens pour réaliser la découpe de pièces de vêtement,
• des moyens de transmission de données entre le dispositif de visualisation et les moyens pour réaliser la découpe des pièces de vêtement.

The invention also relates to a device for producing garment parts, comprising:

• a display device according to the invention, as above,
• means for producing the cutting of pieces of clothing,
• means for transmitting data between the display device and the means for producing the cutting of the garment pieces.

The means for making the cutting of the pieces of clothing can be controlled by a microcomputer, the means of data transmission then connecting the display device and the microcomputer.

The means of data transmission can by example to be part of a communication network.

Brief description of the figures

• la figure 1 illustre un procédé de simulation d'assemblage selon l'art antérieur ;
• les figures 2 à 6 sont des exemples d'étapes d'application de pièces de vêtement à un mannequin, dans le cadre d'un procédé selon l'invention ;
• la figure 7 illustre une étape d'insertion d'une ligne homologue sur un mannequin ;
• la figure 8 représente schématiquement une portion d'un mannequin et un système de repérage en coordonnées elliptiques ;
• les figures 9A et 9B représentent schématiquement, respectivement, des lignes caractéristiques d'une partie d'un mannequin et une partie d'un mannequin, topologiquement homologue à une pièce de vêtement ;
• la figure 10 représente la partie de mannequin de la figure 9B, en développement dans un plan ;
• la figure 11 représente une triangulation d'une pièce de vêtement ;
• la figure 12 représente des étapes d'un procédé pour plaquer une pièce de vêtement contre le mannequin ;
• la figure 13 représente schématiquement un procédé économique en déplacement pour rétablir les longueurs d'une chaíne de droites comprimée ;
• la figure 14 représente des étapes d'un procédé de relaxation selon l'invention ;
• les figures 15A et 15B représentent un noeud de maillage entouré de triangles ;
• la figure 16 représente un polygone, dans un ensemble de triangles, ce polygone contenant tous les points qui voient les contours extérieurs de tous les triangles ;
• les figures 17A et 17B représentent le déplacement d'un point de maillage triangulaire évitant les problèmes de retournement ;
• la figure 18 représente la zone de déplacement d'un point de maillage triangulaire, compatible avec la condition de non-retournement ;
• la figure 19 représente schématiquement un procédé général d'habillage de mannequin, de simulation et d'analyse de "portabilité" selon l'invention ;
• la figure 20 représente les étapes d'un procédé d'habillage de mannequin selon l'invention ;
• les figures 21A et 21B représentent un dispositif pour la mise en oeuvre de l'invention, et
• la figure 22 représente un dispositif de découpe, couplé à un dispositif de simulation et de visualisation selon l'invention.

The features and advantages of the invention will become more apparent in the light of the description which follows. This description relates to the exemplary embodiments, given for explanatory and nonlimiting purposes, with reference to the appended drawings in which:

• FIG. 1 illustrates an assembly simulation method according to the prior art;
• Figures 2 to 6 are examples of steps of applying garment parts to a manikin, in the context of a method according to the invention;
• Figure 7 illustrates a step of inserting a homologous line on a manikin;
• Figure 8 schematically shows a portion of a manikin and a tracking system in elliptical coordinates;
• Figures 9A and 9B show schematically, respectively, characteristic lines of a portion of a dummy and a portion of a dummy, topologically homologous to a piece of clothing;
• Fig. 10 shows the mannequin portion of Fig. 9B, developing in a plane;
• Figure 11 shows a triangulation of a piece of clothing;
• Fig. 12 shows steps of a method for pressing a piece of clothing against the manikin;
• FIG. 13 schematically represents an economical displacement process for restoring the lengths of a compression line of straight lines;
• Figure 14 shows steps of a relaxation method according to the invention;
• Figures 15A and 15B show a mesh node surrounded by triangles;
• Figure 16 shows a polygon, in a set of triangles, this polygon containing all the points that see the outlines of all the triangles;
• FIGS. 17A and 17B show the displacement of a triangular mesh point avoiding the problems of reversal;
• FIG. 18 represents the zone of displacement of a triangular mesh point, compatible with the non-inversion condition;
• Figure 19 schematically shows a general method of manikin dressing, simulation and analysis of "portability" according to the invention;
• FIG. 20 represents the steps of a manikin dressing method according to the invention;
• FIGS. 21A and 21B show a device for implementing the invention, and
• FIG. 22 represents a cutting device, coupled to a simulation and display device according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In the following, we call "mannequin" a representation computing the volume (or useful part of the volume) of a manikin clothing or a human body. For the purpose of explanation, the volume will be assumed to be described by its external surface, itself described as a triangular mesh, the vertices of the triangles of the mesh being points of this outer surface. Other representations are possible (parametric external surface, or the volume defined by voxels (small volume elements)).

The manikin can therefore be represented by data stored in a memory of a computer or a system computer data, these data corresponding for example to a mesh triangular, or to a parametric outer surface, or to these voxels.

Various types of manikins can be defined, depending on different parameters, for example the age and / or sex of the person that the model represents. It is possible to provide various types of dummy, and make a selection of a particular type of dummy. In particular, a database "mannequins" can be initially defined, in which a user can select a manikin particular, depending on the needs. Such a database can be previously stored in a computer system, as described later in this text.

U.S. Patent No. 5,850,222 discloses a modeling of manikin, usable in the context of the present invention.

"Clothing" means the computer representation of two-dimensional pieces (2D) of a garment, by their lines of finish and their cutting. The finish of a room is the set of lines delimiting the apparent part of the piece once mounted. The finish contains the lines stitching, the visible limits of the hems and fold lines or clamp. The finish is associated with an implicit concept of interior. The part of outer fabric to finish (ie between finish and cut) is called the seam value. The parts are supposed to be described with the x-axis corresponding to the warp direction of the fabric (the "straight line"), where they must be cut out.

The garment can therefore be represented by data stored in a memory of a computer or a system computer, these data corresponding for example to the finished lines and cutting.

Again, various types of clothing can be defined, in function of different parameters, for example the age and / or sex of the person to whom the garment is intended. It is possible to predict various types of clothing, and to make a selection of a type of special clothing. In particular, a database "clothing" can be initially defined, in which a user can select a particular garment, as needed. Such a database can also be previously stored in a computer system, as described later in this text.

A preliminary step of a method according to the invention can therefore consist in the selection and / or visualization of a type of manikin and a particular type of clothing.

In a general manner, the method according to the invention is first step of depositing pieces of clothing on the surface, or against the surface of the manikin. But we do not take into account, for this step, respect for the geometry or physical behavior of the tissue. We only take into account the relations of continuity, classical in topology; for example, deformations are carried out continuous, without tearing or intersection.

In one example, illustrated in FIG. 2, a part is applied 30, called "half-front", on the corresponding surface of the bust 32 of a dummy.

It is possible, in the case of partial parts, and as illustrated in FIG. 3, previously fusing pieces 34, 36 (or stored data or stored data sets corresponding, representative of these pieces) to obtain a piece 30 (or representative data of such a room) to be applied to the part 32 of the manikin. Each of the pieces 34, 36 can do initially part of the database used by the maker.

It is also possible, as illustrated in Figure 4, in the case of a piece of clothing 38 comprising one or more gripper (s) 40, close the one (s) prior to the application or filing of the piece on the mannequin. This closure of the clamps does not require to respect the lengths of the room. It is done on the data that represent the piece of clothing.

In certain cases of atypical or complex parts, it is it is preferable to cut the part (or the data that represents the piece) in sub-pieces of more classic shape, so as to simplify the step of depositing or applying the part to the surface of the manikin.

Thus, FIG. 5 represents a part 40 of shape initially complex, with the front and rear parts of a same half-room. Cutting makes it possible to isolate the part before 30 which is then applied to the manikin 32. Again, a cutting Corresponding data representative of the piece 40 is made.

In some cases, depending on the type of clothing or room, will apply this one or this one, not directly to the initial surface manikin, but to a surface deducted from the manikin or deducted from the outer surface that defines the manikin.

This result can be obtained by calculating the convex hull the usable area of the manikin or part of the dummy.

In the case of a useful surface with two parts separated from the manikin, the surface area resulting from the accumulation of convex polygons of selected sections, by horizontal example, of the two parts considered of the manikin.

For example, as shown in Figure 6, in the case of a skirt 44 (or a dress, etc.), the garment does not fit anymore topologically on the surface of the manikin 48: the surface of the skirt, once it is applied in three dimensions, has two holes 43, 45, while the manikin's usable area (reduced to the legs and basin) has three holes 47, 49, 51. So we correct the surface of the manikin filling the space between the two legs. The method simpler is to use a mannequin already presenting this property. We can also automatically obtain this result by calculating the convex hull of the usable surface of the manikin or, more just yet (from the point of view of computing time), by calculating the surface resulting from the accumulation of convex polygons of sections horizontal legs.

Thus, FIG. 6 represents the application of a panel 44 of skirt to a surface 46 deduced from the manikin 48. The result is equivalent to introducing both legs into a sheath,

The choice between the different techniques, exposed above in connection with FIGS. 2 to 6, will be carried out thanks to the knowledge type of garment, type of room and points and / or lines characteristics of the pieces.

Again, all the transformations and calculations are done on the representative data of mannequins and / or clothing.

To carry out the step of applying the part to the manikin, (or against the manikin) we can define a point-to-point relationship between said piece and the surface of the manikin or between the sets of representative data, respectively, of the piece and the surface of the dummy. This relationship respects the classical continuity relationships topology.

So, every point of the surface of the manikin or (in the case described above with reference to Figure 6) of the area deduced from manikin, is associated with one and only one point of the garment or the piece of clothing to apply.

More generally, we can define bijective relations and continuous (homologies) between the 2D parts of the garment (or corresponding representative data) and portions of surfaces manikin or surface portions simply derived from the manikin (or corresponding representative data).

The examples given above, in connection with FIGS. to 6 can therefore be described in terms of a continuous one-to-one relationship, or point-to-point, or in terms of continuous bijection, that is to say homology.

Figure 2 then corresponds to a homology between a room half-front and the corresponding surface of the manikin, and Figure 6 to a homology between a skirt panel and a surface deduced from dummy. In the case of Figure 5, cutting beforehand the complex part makes it possible to simplify the calculation of the homology.

More generally, we can define relations topology between the garment and the manikin (or body) it dress, or between the representative data of this garment and this manikin or that body, relationships expressed by surfaces and / or curves and / or homologous points.

Thus, according to another example, illustrated in FIG. 7, in the case of a partial piece 50, one can build on the manikin 32 a, or line (s) 52 border (s) to the, or line (s) no Classical (s) 53 of Exhibit 50.

A method for establishing such a method is described below. correspondence or homological relation.

In addition, a mesh of clothing or 2D document, or corresponding representative data, suitable for support the simulation of the fabric, for example a triangular mesh.

Using homology and normals on the surface of the mannequin, then, layer by layer (lining, sheet, pockets), the mesh of the pieces on the 3D surface of the manikin. The pieces are then pressed against the surface of the manikin, so unrealistic. It is possible to add a small thickness between successive layers, in order to put the pieces in the order they are will present at the end of the process.

Seams (or splices) are then made between Meshes of parts using 3D lines and adjacency geometric meshes.

The garment is then topologically complete, sewn and donned on the mannequin. On the other hand, it is generally extremely compressed and distorted (it can be stretched in places for example) and this physically unfeasible. This is normal since the garment is pressed against the manikin; indeed, as already explained above, the initial steps of the method according to the invention do not take respect for the mechanical and / or geometrical aspect of the constituent material of the garment.

Moreover, for a given form of piece of clothing, the result of this "plating" is the same regardless of the length or size of said piece of clothing.

A method will now be described, which helps to build a homology between the manikin and a piece of clothing.

• tronc et bassin
• jambes (ou haut et bas de la jambe)
• bras (ou avant et arrière-bras).

The manikin is first separated into different simple parts:

• trunk and basin
• legs (or up and down the leg)
• arm (or forearm and forearm).

If a coin covers more than one of these parts, the coin is cut also according to a homologous line, as already described above in connection with Figure 5.

As illustrated in FIG. 8, the parts of the manikin are described in elliptical coordinates. For each part, one chooses the axis AA 'most adapted: in the case of the example of figure 8 (trunk of the manikin), one chooses for example an axis passing on the one hand by the center of symmetry of a first section S ₁ (passing through the neck) and secondly by the center of symmetry of a second section S ₂ , here an abdominal section. Each point M is thus described by a set of coordinates r, ρ, , where r denotes the distance from the point M to the center O of the coordinate reference. ρ and  make it possible to locate the point M respectively with respect to a horizontal plane and a vertical plane of reference.

It may be that, for some surfaces, there is a couple (ρ, ) corresponding to several values of r. It means that it exists, according to a certain direction, several "levels" of surface of the manikin, at different distances from the center O. In this case, one can modify the volume of the manikin by retaining only the point (s) for which one (s) is maximum. We have already described above another example of modification of the surface of the manikin (Figure 6). It's here modified surface or, in the case described here, the area defined by the points of maximum coordinate r, which defines the surface from which homology will be established.

One volume is then isolated topologically counterpart to the piece, using the characteristic lines of the dummy. These characteristic lines define surfaces of the manikin that can be laid flat.

• L1, L3 : lignes définissant l'emmanchure droite
• L2, L4 : lignes définissant l'emmanchure gauche
• L5 : ligne définissant l'épaule droite
• L6 : ligne définissant l'épaule gauche
• L7 : ligne définissant le côté droit
• L8 : ligne définissant le côté gauche
• L9, L11, L12 : lignes définissant la taille
• L10 : ligne définissant le milieu, devant
• L13, L14, L15 : lignes définissant le cou
• L16, L18 : lignes définissant le poignet droit
• L17, L19 : lignes définissant le poignet gauche
• L20, L22 : lignes définissant le coude droit
• L21, L23 : lignes définissant le coude gauche
• L24, L26 : lignes définissant l'avant bras droit
• L25, L27 : lignes définissant l'avant bras gauche
• L28, L30 : lignes définissant l'arrière bras droit
• L29, L31 : lignes définissant l'arrière bras gauche

Examples of such lines Li (i = 1,2, ... 31) are given, for the top of a manikin, in FIG. 9A:

• L1, L3: lines defining the right armhole
• L2, L4: lines defining the left armhole
• L5: line defining the right shoulder
• L6: line defining the left shoulder
• L7: line defining the right side
• L8: line defining the left side
• L9, L11, L12: lines defining the size
• L10: line defining the middle, in front of
• L13, L14, L15: lines defining the neck
• L16, L18: lines defining the right wrist
• L17, L19: lines defining the left wrist
• L20, L22: lines defining the right elbow
• L21, L23: lines defining the left elbow
• L24, L26: lines defining the right forearm
• L25, L27: lines defining the left forearm
• L28, L30: lines defining the right back
• L29, L31: lines defining the left hind-arm

Figure 9B shows the front upper part of a mannequin, cut along certain characteristic lines.

We then project (Figure 10), on the plane (ρ, ), this part counterpart (or representative data for this part). This operation and the resulting contour are called the "projection" of the piece on the mannequin. The data relating to this projection are stored.

This projection is in bijection with the surface (corrected by the maximum radius) of the manikin.

In fact, therefore, a projection is made beforehand, on a plan, of the selected area of the manikin. Thus is established a first bijection between the surface (in 3D) of the manikin (or data representative of this surface) and its projection on a plane.

Moreover, as illustrated in Figure 11, from the shape of the room, we build a triangulation, maintaining the same number of points on the contoured parts sewn together with other rooms.

We will then progressively deform the triangulation (the "mesh") of the piece to bring it to coincide with its projection, in avoiding any inversion of triangles. The displacement is described later a triangular mesh point, without reversal.

The deformation algorithm used consists, at each step, to first move the points of the contour to a new position closer to the desired contour, while respecting the constraint of non-flipping triangles, while ensuring that the new contour remains a simple polygon, that is to say does not auto-intersect. he There are two possibilities for triangles to be superimposed: by flipping a triangle, or in the case of a complex polygon. Then all the other points of the triangulation are moved to the location of the average points surrounding them, in respecting the constraint of non-inversion of the triangles. For each point, is calculated the center of gravity of its neighbors, and this point follows this centroid. The deformation of the triangular mesh is therefore based on effects of average displacements.

In practice, the initial and final contours are sufficiently similar so that it is often unnecessary to respect the constraint "simple polygon". It is sufficient if the initial triangulation is reduced, by a scale factor, to fit within its projection. We can then go in a straight line, step by step, from the outline of the mesh to the corresponding point of the projection.

We thus obtain a reversible projection of each point of the piece on a point of the manikin. Data concerning this projection are stored. Practically, we memorize the correspondences of the vertices of the triangles with points of the projection of the manikin. We obtain, moreover, the lines to sew (whose corresponding data are also stored).

An application of this projection allows to set up the parts on the surface of the manikin.

• une première bijection, entre le mannequin ou une partie de celui-ci, défini(e) en trois dimensions, et une projection de ce mannequin ou de cette partie, en deux dimensions,
• une seconde bijection, entre la projection du mannequin et la, ou les, pièce(s) correspondante(s) de vêtement, qui a (ont) une représentation bidimensionnelle.

Indeed, according to the invention, two bijections are successively carried out:

• a first bijection, between the manikin or a part thereof, defined in three dimensions, and a projection of this manikin or this part, in two dimensions,
• a second bijection, between the projection of the manikin and the or the corresponding piece (s) of clothing, which has (have) a two-dimensional representation.

Using the stored data concerning these operations, a combination of these two bijections allows to clothe the garment (or its innermost layer) against the surface of the manikin, or again to put the garments on the surface of the manikin, since each point of the piece of clothing considered is in correspondence with a point on the surface of the manikin.

The layers, constituting the garment (lining, canvas, collar ...), are placed in 3D in successive layers separated by a sufficiently small thickness to preserve the bijectivity. This thickness is related to the minimum radius of curvature of the surface of the dummy.

More specifically, for each portion of the manikin, the thickness separating two successive layers is chosen very small before the radius of curvature of said portion of the manikin, and the sum of successive thicknesses is less than this same radius of curvature. The innermost layer is preferably pressed against the mannequin; in other words, the thickness separating this inner layer from the surface of the manikin is nil.

We then realize the seams, or the junction of the pieces of clothing according to their sewing lines, that is to say, the fusion of the points and sides belonging to the stitched edges (the bijectivity allows them to find). This operation is performed on the representative data pieces at the end of the stage of placement on the surface of the dummy.

Figure 12 summarizes the plating operations of a garment against the manikin that are actually made on the data representative parts of clothing and manikin.

In a first step (S26), the volume of the manikin a part topologically homologous to the piece.

Then (step S28) this part is projected in two dimensions, on a plane.

The triangulation of the piece of clothing, obtained previously or simultaneously to previous operations, is then deformed (step S29).

The data obtained during these last two stages can be stored.

Then, (step S30) the different layers of garment against the surface of the manikin.

Finally, the seams are made (joining pieces of clothing (or their representative data) according to their lines of sewing: step S31).

The garment is then ready for relaxation.

The purpose of relaxation is to bring back each piece of clothing towards his state of equilibrium. More precisely, the energy state tissue, initially very high due to topological treatment explained above, is brought back to a value close to the minimum, compatible with the launch of the simulation of the material. Different algorithms are possible. We can use a model more or less simplified and / or realistic tissue simulation (managing collisions), by direct introduction into such a model.

Comparison of the different characteristics of the tissues shows that (in general) the dominant energy factor (for a any displacement) is the tensile strength. This last is usually at least 100 times larger than resistance to shear, and even greater with respect to bending resistance, for typical curvatures. Curvature resistance becomes no negligible if you try to bend the fabric at a sharp angle.

The most economical method on the move to restore the lengths of a compressed straight line (the compression is the general case) consists, as illustrated in Figure 13, in "crumpling" the line.

This is what is conventionally done, for example in the framework of algorithms moving each point to restore distances with his neighbors. But, problems then arise, related to obtaining curvatures too important. Moreover, the folds obtained are then a direct function of the mesh step, and are therefore not parameters physical. Finally, fast anti-collision algorithms have times generally related to the regularity of the surfaces to be treated.

The introduction in the algorithm of a resistance to curvature to combat wrinkling results in weighted calculations; in addition, the curvature resistance must be then exaggerated (relatively to that of tissue), and this may lead to blocked solution (local minimum), where high tensile strengths remain, offset by strong resistance to curvature.

According to the invention, it is also possible to treat the problem from large areas, then "go down" to small areas. For example, one homogeneously "deforms" first of all the garment, preferably by seeking a minimum of traction energy (the examples of energy calculation are given below). Then we deform a set of large sub-parts of the garment, then sets of smaller and smaller parts ... etc. The size of a part can be defined according to the number of triangles that it contains: thus, the average number of triangles of each part of the first set is chosen larger than the average number of triangles of each part of the set next, and this second number is itself larger than the average number of triangles of each part of a third set ... etc. The crumpling is avoided by using "soft" deformations of space, that is to say, preferably continuous, differentiable and more preferably whose derivative is continuous (function C ² , from a mathematical point of view) .

This technique has the following advantage. Deformation chosen is a deformation (continuous and differentiable) of space, instead of simply a deformation of the fabric. So we move each point according to its position in space, and not according to its position relative to its neighbors. The deformations can then be chosen to respect the topological relations of the volume Euclidean. The result of this choice is that the calculation of tissue collisions becomes useless: the lining can no longer cross the canvas, the sleeve does not can no longer touch the small side, the garment can not penetrate the mannequin ... etc. The triangulation is preferably chosen dense enough so that the deformation of the space around a elementary triangle can be considered linear.

Calculations are made on the representative data of the pieces of clothing.

The mannequin remains, him, undistorted.

To obtain a deformation satisfying the above criteria, it is enough to move, in a sense, along lines of field (potential field of view) from the manikin, and in the other two directions, along the very surface of the fabric at the moment considered, avoiding, in this local reference to the fabric, any reversal of triangle. At the edge of the fabric (where the surface is not defined), just stay on the same equipotential. To avoid undressing in the case of a dummy too simple (this is particularly the case of a trunk without the arms), one can for example induce a low tendency to descend.

The cost of calculating a potential field is high, but the result depends only on the manikin (and the type of field chosen). he then simply store, or store, these field lines with the dummy. Lines quickly end up being rights which avoids calculating or storing them on a large scale. length.

The calculation of a potential field is given in the book entitled "Introduction to Implicit Surfaces", edited by J. Bloomenthal et al., Morgan Kaufmann Publishers The Morgan Kaufmann Series Computer Graphics and Geometric Modeling, 1997.

We choose a deformation function along each line of field. This function is optimized according to a criterion of minimization of energy.

The subdivision of the part of clothing (or data corresponding) to be treated may be to isolate related areas globally compressed or stretched. An arbitrary related breakdown works just as well, at the cost of a slight degradation of performance.

The desired result is then achieved: the garment is sewn, entity on the manikin, and it suffers only weak constraints, compatible with the launch of a realistic simulation of the fabric.

The traction energy of each piece is calculated in relation to at the initial position of this piece, in two dimensions.

For example, we calculate, for each triangle of the triangulation of the considered part, the variation of energy since the initial position of the triangle, and then the sum of the variations of energy of all the triangles.

For each triangle, we can take, as a measure of the energy, the variation of the length of one of its side or the variation of its perimeter.

For each triangle, we can also calculate the energy in function of its position in 3D (on the manikin), of its position of rest in the plane, and a value of the stiffness K of the fabric.

We give below an example of module of calculation of the energy, for each triangle, in language C ++.

FIG. 14 represents steps of a method of relaxation according to the invention. Again, these steps are performed on the memorized data of clothing.

A first set of parts is defined according to its size (step 340).

A deformation function is then selected for each field line (step S341). This function is optimized according to of a criterion for minimizing energy (step S342). Function energy has of course been previously defined.

Once the optimization obtained, we define another subset smaller parts (step S344) and a function of deformation is again chosen according to the field lines, and is optimized. The algorithm stops when the operator judges the result satisfactory, or after a predetermined number of iterations (step S343).

The question of moving a mesh point triangular, without flipping, will now be treated.

The problem will be explained in connection with the figures 15A and 15B. Let a mesh node No, surrounded by triangles. We wants to move No without inducing a "reversal", as it is produces one in Figure 15B.

So we first calculate (figure 16) the polygon (convex) containing all the points P such that "path" the outer contour of the triangles. This is the intersection (hatched in Figure 16) of the 1/2 plans defined by all sides of the outline. This intersection is not empty, since the original node No respects the constraint. We take note that, if the contour is convex, no calculation is necessary, any point to the contour interior being then a point P.

The result is a convex polygon. We can then calculate an intermediate endpoint No ', respecting the direction of the triangles, as illustrated in Figure 17A. Figure 17B shows the polygon obtained.

The problem is the same for a point at the edge (that is to say not entirely surrounded by triangles), except that the convex obtained can be opened, as shown in Figure 18.

Therefore, a triangular mesh point is moved without reversing triangles, provided that the displacement is limited within a polygon delineating all the points that see directly from the inside, the outer contour of the triangles.

Respecting the non-reversal constraint therefore consists in test the direction of rotation of the triangles adjacent to the point to be moved considered, and, if a reversal is detected (a direction of rotation which reverses), try a lower displacement (for example half initial displacement). In case of total failure, we can try to Unlock the situation by moving the point randomly.

FIG. 19 is a general diagram of a method according to the invention, whose operations described above can be part of.

In a first step (S10), the shapes, or subassemblies of clothing, are defined flat, in two dimensions. At during this stage can also be defined positions assembly of the different parts. This step can be implemented using the software marketed by Lectra under the designation "Modaris".

Step S20 groups the dressing operations of the manikin, as already described above.

In particular, the pieces of clothing, after having been selected, are placed against the surface of the manikin without consider their physical parameters. Then, the operation takes place junction parts between them, then relaxation.

A simulation step (S40) can then take place, by example by the finite element method. A simulation method which can be used is described by D. Baraff et al. "Large Steps in Cloth Simulation ": Sigraph 1998, Computer Graphics Conference Proceedings, Addison-Wesley, ISBN 0-201-30988-2.

The "portability" of the garment can then be analyzed (step S50): the operator can then visualize the garment, analyze the configuration or overall impression. If something does not not satisfied (a particular piece of clothing is, for example, badly adapted to a part of the body), it is possible to select a new piece of clothing replacing the previous one, or else modify the piece of clothing, for example using the software "Modaris" of the applicant.

In this case, the manikin is dressed again (step S20). The process is then reiterated from the stage where the pieces are plated on homologous forms of the manikin and laid flat. We reports, by bijectivity, the data on the surface of the manikin for the form or part that has undergone a modification or substitution. Then, the edges of the part are joined with the neighboring parts. The relaxation process can then be performed again, and will act on all the garment to bring it to its position of balance on the dummy. Thus, all interactions can be taken into account possible between the modified part and all other parts of clothing.

Otherwise, the manufacture of the garment (step S60) can take place.

Figure 20 is a detailed flowchart showing a dressing method according to the invention.

In a first step (S21) the flat pattern (two-dimensional representation) and the manikin are selected.

It can then be checked (step S22) if there is compatibility topological relationship between the type of garment selected and the corresponding dummy. For example, it can be checked whether the number of holes in the garment corresponds to that of that part of the dummy. If there is no compatibility, we can proceed with the alteration of the manikin (step S23), for example by melting parts of the manikin or by determining a surface deduced from the manikin, as already explained above.

Steps S24 (S241-S244), S25 and S26 are performed for each pair consisting of a piece of clothing and a surface or part of the manikin.

• étape S241 : fusion de la pièce avec une autre pièce
• étape S242 : coupure de pièce complexe
• étape S243 : insertion de ligne homologue sur le mannequin
• étape S244 : fermeture de pince.

If one is in a case of partial part, or part comprising a clamp, or of complex part, one of the following stages can be realized:

• step S241: merge the part with another part
• step S242: complex piece cut
• step S243: homologous line insertion on the manikin
• step S244: Clamp closure.

Then, the part is meshed (step S27), this which determines the number of points to be matched with points of the manikin, as well as flattening the surface corresponding manikin (step S28).

The contour of the part can then be brought to the contour of the projection of the manikin (step S29): the mesh is therefore gradually deformed.

This produces (S33) the "painted" garment on the manikin.

This step S33 completes the placement of the garment on the dummy.

The garment can then be relaxed (step S34). comes then the mechanical simulation step (S38), which allows, for a tissue given, to find the right drape, and that eliminates the last deformations. We obtain a realistic image of the garment put on the manikin (S39).

An example of a device, illustrated in FIGS. 21A and 21B, will now be given, for the implementation of the method according to the invention. This device is generally designated by reference 119.

Fig. 21A globally represents a graphics station comprising a microcomputer 120 configured appropriately for processing, according to a method according to the invention, of models of mannequin and garment parts, a display device 122 and control devices (for example a keyboard 124 and a mouse 125). The microcomputer 120 includes a calculating section with all electronic components, software or other, necessary for the simulation of the dressing of a manikin with pieces of clothing.

• réaliser le dépôt, ou effectuer les calculs de dépôt, des pièces de vêtement sur la surface du mannequin ou sur une surface déduite de celle du mannequin,
• réaliser la jonction, ou effectuer les calculs de jonction des pièces de vêtement selon leurs lignes de couture,
• effectuer une relaxation, ou effectuer les calculs de relaxation, des pièces du vêtement, depuis leur position à la surface du mannequin vers leur position d'équilibre.

Thus, for example (FIG. 21B), the system 120 comprises a programmable processor 126, a memory 128 and an input device, for example a hard disk 132, coupled to a system bus 130. The processor can be, for example , a microprocessor, or a CPU or workstation processor. The memory 128 may be, for example, a hard disk, a ROM, a compact optical disk, a DRAM dynamic random access memory or any other type of RAM, a magnetic or optical storage element, registers or other volatile and / or nonvolatile memories. A manikin dressing algorithm includes instructions that can be stored in the memory, and that allow the manikin to be dressed with one or more pieces of clothing, in accordance with any of the embodiments of the present invention. A program for implementing the method according to the invention is resident or recorded on a medium (for example: floppy disk or CD ROM or removable hard disk or magnetic medium) that can be read by a computer system or by the microcomputer 120. This program concerns a method of dressing, with pieces of clothing, a manikin represented in three dimensions. It includes instructions for:

• depositing, or performing the deposition calculations, garment parts on the surface of the manikin or on a surface deduced from that of the manikin,
• make the junction, or perform the calculations of joining the pieces of clothing according to their sewing lines,
• perform relaxation, or perform the relaxation calculations, of the pieces of clothing, from their position on the surface of the dummy to their position of equilibrium.

The microcomputer may comprise calculation means, to calculate for example the projections of the selected parts of the manikin, or to calculate values of the field lines of if they are not already associated with the manikin selected, or to perform the triangulation and their deformations, and / or the operations of application of the garment to dummy. These calculation means also make it possible to carry out the energy calculations (traction energy) and minimization calculations of these energies during relaxation ..

The microcomputer 120 can be programmed to generate mannequin shapes. or such forms can be previously stored, for example in the memory 128. even forms of clothing pieces can also be previously stored. In this case, means are provided which select a manikin and one or more pieces of clothing. These elements may have been obtained by CAD or by automatic generation systems.

The microcomputer 120 can also be connected to other peripheral devices, such as, for example, devices 132. It may be connected to an electronic network, for example example Internet or Intranet type, to send data mannequins and / or clothing.

It is possible to display on the screen 122 an image representing a manikin selected by an operator. This one also selects pieces of clothing, which are deposited against the surface of the manikin, regardless of their parameters physical and as already explained above. There may be a display intermediate, on the device 122, parts of the clad garment against the manikin, so in their compressed state, before relaxation. Then, there is the operation of joining the pieces together, then the step of relaxation.

The operator can then visualize the garment, analyze the configuration or overall impression, and if something does not not satisfied, he can select a new piece of clothing replace the previous one, or modify a piece of clothing.

It is also possible to physically realize the garment, for example by cutting operations of parts in a fabric, after validating these pieces by simulation. Such an operation cutting can be done according to processes and with devices known, for example as described in US-5,825,652.

Such a device is illustrated in FIG. means 136 of cutting table type, on which can be positioned sheets 138 of material to be cut, for example fabric, means 140 for positioning and moving a tool 150 above this table, and means 142 of steering or controlling these positioning and cutting. The control means are computer means. they may further include means 144 for viewing the room to be cut, whose data has been transmitted and / or means of viewing the area of the workpiece positioned on the cutting table.

The data concerning the parts, which have been validated according to the invention by simulation using the device 119, can for example be transmitted to the control means 142 of the cutting device via a link 146 of a communication network electronic. It is also possible to memorize the data on a floppy disk, and then load them into a memory means 142 for controlling the cutting device.

Claims (32)

1. A method of viewing a garment made up of garment pieces, represented by data stored in a memory of a computer (119), and having seam lines, on a dummy model represented by data stored in a memory of a computer (119), said method comprising:

   placing the garment pieces (30, 34, 36, 38, 40, 44, 50) on the surface of the dummy model (32, 42) or on a surface (48) derived from the surface of the dummy model;

   joining together the garment pieces along their seam lines; and

   relaxing each garment piece from its position on the surface of the dummy model to its equilibrium position on the dummy model.
2. A method according to claim 1, the garment pieces being placed on the surface of the dummy model by establishing a bijective and continuous relationship between at least a portion of a garment piece and a corresponding portion of the surface of the dummy model.
3. A method according to claim 1 or 2, the garment pieces being placed on the surface of the dummy model by establishing a bijective and continuous relationship between points representative of a garment piece and points on a corresponding portion of the surface of the dummy model.
4. A method according to claim 2 or 3, the establishing of a bijective and continuous relationship between a garment piece and a corresponding portion of the surface of the dummy model comprising:

   selecting a portion of the dummy model that corresponds topologically to the garment piece;

   projecting said portion of the dummy model on a plane; and

   deforming the piece to bring it to coincide with said projection.
5. A method according to claim 4, in which:

   a triangulation of the garment piece is performed; and

   the triangulation of the piece is deformed to bring it to coincide with said projection.
6. A method according to claim 5, the triangulation of the piece being deformed by:

   displacing points defining an outline of the piece to points on an outline of said projection; and

   displacing the points that are vertices of triangles within the outline of the piece.
7. A method according to claim 5 or 6, the triangulation being deformed while satisfying a constraint whereby the triangles of the triangulation of the piece must not be turned over.
8. A method according to any one of claims 1 to 7, the relaxing of a garment piece comprising:

   subdividing the garment piece into a first set of portions; and

   deforming said set of portions while minimizing an energy function of the garment piece.
9. A method according to claim 8, the relaxing of the garment piece further comprising:

   subdividing the garment piece into a second set of portions that are smaller than the portions of the first set; and

   deforming the second set of portions while minimizing an energy function of the garment piece.
10. A method according to claim 8 or 9, the energy function representing the traction energy of the garment piece.
11. A method according to one of claims 8 to 10, the energy function of the garment piece being computed relative to the position of the piece in two dimensions, and as a function of a value for the stiffness K of a fabric.
12. A method according to claim 8 to 11, the deforming of the sets of portions comprising:

    a displacement along field lines coming from the dummy model; and

    a displacement along the surface of the fabric, in the other directions.
13. A method according to claim 12, data corresponding to the field lines being pre-stored.
14. A method according to one of claims 9 to 13, the portions of the first and second sets of portions being connected zones of the garment piece.
15. A method according to one of the preceding claims, a garment piece being provided with a dart cut (40) which is closed prior to placing said piece on the surface of the dummy model (32).
16. A method according to one of the preceding claims, two garment pieces (34, 36) being joined together prior to placing them on the surface of the dummy model (32).
17. A method according to one of the preceding claims, one of the garment pieces (40) being previously cut out into at least two sub-pieces before being placed on the surface of the dummy model (42).
18. A method according to one of the preceding claims, further comprising:

    selecting one of the relaxed garment pieces referred to as a "piece to be replaced";

    selecting another garment piece referred to as a "replacement piece";

    placing the replacement piece on the surface of the dummy model;

    joining the replacement piece to the other pieces along its seam lines, where applicable; and

    relaxing all of the garment pieces from their position on the surface of the dummy to their equilibrium position on the dummy model.
19. A method according to one of the preceding claims, further comprising:

    selecting one of the relaxed garment pieces referred to as a "piece to be modified";

    modifying said piece;

    placing said piece as modified on the surface of the dummy model;

    joining the modified piece to the other pieces along its seam lines, where applicable; and

    relaxing all of the pieces of the garment from their position on the surface of the dummy model to their equilibrium position on the dummy model.
20. A method according to one of the preceding claims, further comprising a step of mechanically simulating the garment.
21. A method of making garment pieces, said method comprising:

    pre-viewing the garment on a dummy model using a method according to one of claims 1 to 20; and

    making the pieces of the garment.
22. Apparatus (119) for viewing garment pieces on a dummy model, said apparatus comprising:

    computer means (120, 126, 128, 132) for:

    placing garment pieces on the surface of the dummy model or on a surface derived from the surface of the dummy model;

    joining together the garment pieces along their seam lines; and

    relaxing the pieces of the garment from their position on the surface of the dummy model to their equilibrium position on the dummy model; and

    viewing means (122) for viewing the dummy model and the garment pieces on the dummy model.
23. Apparatus according to claim 22, further making it possible to pre-view the selected dummy model and/or the selected garment pieces.
24. Apparatus according to claim 22 or 23, further comprising means (24, 125) for modifying a selected garment piece or for replacing a garment piece with another garment piece.
25. Apparatus according to one of claims 22 to 24, further comprising means (124, 125) for selecting garment pieces from a preestablished garment database.
26. Apparatus according to one of claims 22 to 25, further comprising means (124, 125) for selecting a dummy model from a preestablished dummy database.
27. Apparatus according to one of claims 22 to 26, further comprising means for storing data relating to the garment pieces and/or to the dummy model.
28. Apparatus for making garment pieces, the apparatus comprising:

    viewing apparatus (119) according to one of claims 22 to 28;

    cutting-out means (136, 138, 140, 150) for cutting out garment pieces; and

    data-transmission means (146) for transmitting data between the viewing apparatus (119) and the cutting-out means for cutting out the garment pieces.
29. Apparatus according to claim 28, the cutting-out means (140, 150) for cutting out the garment pieces being controlled by a micro-computer (142), and the data-transmission means (146) interconnecting the viewing apparatus (119) and the micro-computer.
30. Apparatus according to claim 28 or 29, the data-transmission means (146) being part of a communications network.
31. Computer program including instructions for carrying out a process according to one of claims 1 to 21.
32. Support medium likely to be read by a computer system comprising data or instructions to carry out a process according to one of claims 1 to 21.

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