A method for cutting out part placements in flexible material panels supplied in rolls or coupons

Abstract

Method for cutting part placements in flexible material panels supplied in rolls or coupons. The invention relates to a method for cutting part placements in flexible material panels supplied in rolls or coupons, each panel of which has been printed with the same patterned design. The method comprises an initial step (S1) of digitally characterizing the printed panels, a step (S2) of developing theoretical part placements to be cut in the printed panels using the reference image and with respect to characteristic points thereof, a step (S3) of compensating for the actual deformation of the printed panels to be cut, and a step (S4) of cutting the part placements according to their new geometry. Figure for the abstract: Fig. 1.

Description

Title of the invention: Method for cutting placements of pieces in panels of flexible material packaged in rolls or coupons Technical field

[0001] The invention relates to the general field of cutting out placements of pieces in panels of flexible material packaged in rolls or coupons and on each of which the same patterned design has been printed.

[0002] One field of application of the invention is in particular that of the luxury clothing industry which uses panels printed in noble materials (for example silk twill or organza fabric). Prior art

[0003] In the fashion industry, brands present their clothing collections during fashion shows (for example during "Fashion Week") which they then send to be produced by their subcontractors responsible for industrializing the models presented.

[0004] The subcontractors then produce a prototype of the garment, which is checked and then approved by the brand according to specifications and demanding quality criteria. The brand can then order a certain number of pieces from the manufacturers.

[0005] Most of the time, the constraints imposed by the brand are such that it is not possible to automate this type of cutting and the subcontractors therefore make the garment by hand with very significant labor costs and lead times.

[0006] The material used by brands to make their clothing is typically natural fiber, for example silk twill or organza fabric. This material is generally presented in the form of panels packaged in rolls or coupons and on each of which the same patterned design, repetitive or non-repetitive, has been printed (by a screen method or by digital printing).

[0007] To produce an article or garment from such a material, it is therefore necessary to cut out pieces of the garment from one or more of these panels while respecting high requirements in terms of tolerances relating to the dimensions of the pieces and the connection of the patterns between two pieces.

[0008] In order to guarantee these requirements, it appears necessary to compensate for the deformation of the panels observed after their passage under the scanner of the cutting machine. Indeed, the problems of deformation of the material can take several forms and be due to several factors. In particular, the deformation of the material may be linked to printing (subject to constraints of heat and treatment agents), to the packaging of the material in rolls (constraint of non-uniform winding), and to the depositing (synchronization between the depositing carried out by the feeder and the cutter belt generating folds).

[0009] Furthermore, the deformation can take several forms. It can thus be a shrinkage of the fabric, a localized deformation of the fabric (the fabric is not stable, it has shrunk or enlarged by area of ​​non-homogeneous material), a regular deformation of the fabric (the fabric is twisted in a homogeneous manner), or an irregular deformation (the fabric is twisted in a heterogeneous manner both in the direction of the material and in the direction of the roll). It will be noted that these different forms of deformation can appear independently or accumulate on the same fabric.

[0010] It is known to seek to compensate for these deformations of the panels to be cut by allowing the operator to manually retouch the material deposited on the machine in order to align it as much as possible on the cutting conveyor. However, this process of compensating for deformations has the disadvantage of being manual and dependent on the operators, which poses a problem of productivity and labor significantly increasing the production cost. Statement of the invention

[0011] The main aim of the invention is therefore to overcome such drawbacks by proposing a solution for compensating for panel deformations which does not depend on operators and which does not require reviewing the technical architecture of the cutting machine.

[0012] According to the invention, this aim is achieved by means of a method of cutting out placements of pieces in panels of flexible material packaged in rolls or coupons and on each of which the same patterned design has been printed, the method comprising: - an initial stage of digital characterization of the printed panels including: • the definition of a reference plan for the printed panels; • the acquisition of a real image of a reference panel; • matching characteristic points of the reference plane with corresponding characteristic points of the real image of the reference panel; and • obtaining a reference image of the reference panel with the coordinates of the characteristic points; - a stage of developing theoretical placements of pieces to be cut in the panels printed using the reference image and in relation to characteristic points of the latter, and - a step of compensation for the actual deformation of the printed panels to be cut including: • acquisition of a real image of the printed panels to be cut with detection of their characteristic points; • matching the characteristic points of the reference plane with those of the real image of the printed panels; • the determination of an algorithm for transforming the reference image into the real image of the printed panels; and • the application of the transformation algorithm to the geometry of the parts to be cut from theoretical placements; - a step of cutting the placements of parts according to their new geometry.

[0013] The method according to the invention is remarkable in that it proposes a compensation solution which is based entirely on a software solution which does not require the manual intervention of operators. More precisely, the compensation solution of the method according to the invention makes it possible, by a comparison between a scanned image and a theoretical image of the panels, to adapt the cutting placement of the parts in order to guarantee that they are compatible with the tolerances of the ordering brands.

[0014] In one embodiment, the reference image is obtained by rectifying the real image of the reference panel and its characteristic points.

[0015] In this case, the definition of a reference plane of the printed panels can advantageously comprise the identification within the reference panel of remarkable graphic elements of the design printed on the panel and the association of these remarkable graphic elements with control points with the acquisition of their geometric coordinates.

[0016] The control points of the reference plane may consist of: points of intersection of straight line segments, end points of straight line segments, or points on the outline of geometric figures of the design printed on the panel.

[0017] Matching characteristic points of the reference plane may include translating the control points of the reference plane to match them with the notable graphic elements that they designate in the actual image of the reference panel.

[0018] The determination of a transformation algorithm advantageously comprises the development of two triangular meshes of identical structure from the control points of the reference plane on the one hand, and from the remarkable graphic elements that they designate in the real image of the printed panel, on the other hand.

[0019] The determination of a transformation algorithm can be carried out pixel by pixel for each triangle of the triangular mesh associated with the real image of the reference panel, and the triangular meshes can be developed by applying a Delaunay triangulation.

[0020] In another embodiment, the reference image is directly transmitted with its characteristic points.

[0021] Preferably, the acquisition of a real image of the printed panels to be cut further comprises the acquisition of a thumbnail associated with each characteristic point detected.

[0022] According to one application of the invention, the design printed on the panels is a design with non-repetitive patterns.

[0023] The step of compensating for the actual deformation of the printed panels to be cut can be implemented as a real image of the printed panels is acquired.

[0024] Alternatively, the step of compensating for the actual deformation of the printed panels to be cut is implemented once the entire actual image of the printed panels has been acquired. Brief description of the drawings

[0025] [Fig.l] [Fig.l] is a flowchart showing the main steps of the cutting method according to the invention.

[0026] [Fig.2] [Fig.2] illustrates an example of a panel with a non-repeating pattern to which the method according to the invention can be applied.

[0027] [Fig.3] [Fig.3] shows an example of deformations applied to the panel of [Fig.2],

[0028] [Fig.4] to [Fig.7] Figures 4 to 7 illustrate different steps of an example of developing a reference plan of the panel of [Fig.2] for implementing the method according to the invention.

[0029] [Fig.8] [Fig.8] illustrates an example of the development of triangular meshes for the calculation of a rectified reference image for the implementation of the method according to the invention.

[0030] [Fig.9] [Fig.9] illustrates an example of application of the transformation algorithm to determine the actual deformation of the panel for the implementation of the method according to the invention. Description of the embodiments

[0031] The invention applies to the automatic cutting of pieces from panels of flexible material (for example a silk twill or an organza fabric) which are packaged in rolls or coupons and on each of which the same patterned drawing.

[0032] The automatic cutting of the parts is carried out by means of a cutting system known from the prior art and typically comprising, from upstream to downstream in the direction of advance of the material: a supply module positioned at one end of the cutting table, an acquisition module for scanning the material spread on the cutting table, a cutting module, and a module for unloading the cut parts which is positioned at another end of the cutting table.

[0033] By "panel" is meant here a rectangular area of ​​flexible material on which a single design (with repetitive or non-repetitive patterns) has been printed and from which a single set of pieces (intended for the production of one or more garments) must be cut.

[0034] Typically, a panel will not exceed a few meters in length and its width may occupy the entire width of the strip. In the length direction of the material packaged in rolls or coupons, several identical panels adjacent to each other may be provided, it being understood that the pitch of the pattern printed on each panel is greater than or equal to the pitch of the placements of pieces to be cut in each panel.

[0035] As represented by [Fig.l], the method according to the invention for cutting placements of parts in such panels comprises four main steps, namely: an initial step S1 of digital characterization of the printed panels making it possible to obtain a reference image of a reference panel, a step S2 of developing theoretical placements of parts to be cut in the printed panels using the reference image, a step S3 of compensating for the actual deformation of the printed panels to be cut to modify the geometry of the parts to be cut from the theoretical placements, and a step S4 of cutting the placements of parts according to their new geometry.

[0036] We will now detail a method of implementing the initial step SI aimed at digitally characterizing the printed panels.

[0037] The purpose of this initial step Sla is to obtain a reference image of a reference panel.

[0038] By "reference image" is meant here a plane of the reference panel indicating the position (in a geometric reference frame linked to the panel) of notable graphic elements of the design printed on the panels. The notable graphic elements of the design printed on the panel are more precisely associated with control points whose geometric coordinates are determined and stored.

[0039] In practice, during a first sub-step SS1, an operator defines a reference plane of the panel using Computer Aided Design tools starting either from theoretical data of the panel provided by the designer / donor of order, or of analog measurements carried out on a panel sample (case described below).

[0040] [Fig.2] shows an example of a fabric panel on which a design with non-repeating patterns has been printed. To define the reference plane, the operator begins by defining the geometric limits of the panel (for example, this may be a square with sides of 140 cm), then marks control points within the panel pattern with the acquisition of their geometric coordinates in a geometric reference frame linked to the panel.

[0041] As shown in [Fig.4], the control points can be constituted by points Pi of intersection of straight line segments belonging to the drawn pattern, points Pe of end of straight line segments, remarkable points Pr of the drawn pattern (here the center of a flower), or even points on the outline of geometric figures of the design printed on the panel.

[0042] The geometric coordinates of these control points in the reference frame linked to the panel are determined and stored.

[0043] In order to assist the operator during this operation, it is possible to import an image (if available) in the background to guide him in determining the characteristic shapes of the panel.

[0044] It should be noted that the reference plan of the panels could have been developed by the designer / customer and imported directly (sub-step SS1').

[0045] The next sub-step SS2 consists of acquiring a real image of a reference panel using a scanner.

[0046] In practice, the flexible material passes under a scanner and the image of it is digitally reconstructed to be exported to a characterization application.

[0047] [Fig. 3] shows an example of obtaining a real image of a reference panel corresponding to the fabric panel of [Fig. 2]. In this figure, we see that the fabric has undergone deformations whose consequences on the pattern are visible (certain lines of the drawing are no longer straight but curved).

[0048] The following sub-step SS3 consists of the operator matching the characteristic points of the previously defined reference plane with corresponding characteristic points of the real image of the reference panel.

[0049] In practice, the operator has to translate each characteristic point of the reference plane to position it in the real scanned image on the remarkable graphic element that it designates.

[0050] Figures 5 and 6 illustrate an example of implementation of this sub-step from a portion of the panel of Figures 2 and 3.

[0051] [Fig.5] represents a part of the reference plane Z previously defined with all of its control points P.

[0052] [Fig.6] shows how the control points P are adjusted to match them with the remarkable graphic elements that they designate (this adjustment is illustrated by displacement vectors V).

[0053] This adjustment then makes it possible to obtain a reference image Z' of the reference panel (sub-step SS4) with the position of its control points P' after having been adjusted (see [Fig.7]).

[0054] The reference image Z' of the reference panel and the position of its control points are used to develop one or more placements of parts to be cut in the panels (step S2 of the method).

[0055] In a known manner, these placements are developed in particular by taking into account the constraints of connections between the pieces of clothing.

[0056] We will now detail a method of implementing step S3 of compensating for the actual deformation of the printed panels to be cut.

[0057] In a first step, the flexible material to be cut is positioned at the input of the cutting machine and passes under the acquisition module (i.e. scanner) thereof. The acquisition module makes it possible to acquire a real image of a first panel to be cut (sub-step SS5).

[0058] A processing algorithm automatically identifies the characteristic points on the real image and then automatically matches the characteristic points of the reference plane (defined in sub-step SS4) with those of the real image of the scanned printed panel (sub-step SS6).

[0059] This automatic matching by the processing algorithm consists of translating each characteristic point of the reference plane to position it in the real image of the scanned printed panel on the remarkable graphic element that it designates.

[0060] The following sub-step SS7 consists of determining an algorithm for transforming the reference image into the real image of the printed panels.

[0061] According to an embodiment of this sub-step SS7, this transformation algorithm is obtained by developing two triangular meshes of identical structure from the control points of the reference plane on the one hand, and from the remarkable graphic elements that they designate in the real image of the printed panel, on the other hand.

[0062] In this embodiment, the idea is to construct two triangular meshes MO, Ml from these two clouds of control points, these two meshes being of identical structure and corresponding respectively to the cloud of control points in the reference frame of the reference image and to the cloud of control points in the reference frame of the real image of the scanned panel.

[0063] As shown in [Fig.8], it is understood that the triangular meshes MO, Ml are identical if a triangle (for example CO, DO, GO) exists in the mesh MO, then the triangle (here Cl, Dl, Gl) exists in the mesh Ml (and vice versa).

[0064] The two triangular meshes MO, Ml can be developed by applying a Delaunay triangulation known to those skilled in the art. Such a triangulation aims to maximize the smallest angle of all the angles of the triangles in order to avoid ending up with very elongated triangles.

[0065] The next step in the construction of the transformation algorithm consists of generating the reference image by straightening, triangle by triangle, between the triangular mesh MO covering the reference image and the triangular mesh Ml covering the real image of the scanned panel.

[0066] When seeking to transform a first image and a second image using a transformation function defined in the Euclidean plane (for example a rotation or a homothety), one of the known methods consists of scanning each pixel of the arrival image and applying to it the color of the pixel located at the starting position in the first image, this position being obtained by applying to the coordinates of the pixel the inverse transformation (i.e. reciprocal) of the transformation function.

[0067] In the present case, the real image of the scanned panel is known, as are all the pixels located in each triangle of the Delaunay triangulation ML. For each pixel PO located in the triangle T0 (A0, B0, C0) of the image 10 (i.e. the rectified image to be reconstructed) and whose analogous triangle in the scanned image II is the triangle Tl (A1, B1, C1), the color to be assigned to PO is determined by calculating the reciprocal position of PO in the real image.

[0068] We denote (xO, yO) the real coordinates of the point PO located at the center of the pixel of the image 10 and whose color we wish to calculate. We then wish to calculate the point PI with real coordinates (xl, yl) such that the position of PI relative to the triangle Tl corresponds to the position PO relative to the triangle T0. This bijective function uses the notion of barycentric coordinates.

[0069] For a point P located in a triangle (A, B, C), if we define (kA, kB, kC) by: kA = a / (a+b+c); kB = b / (a+b+c); and kC = c / (a+b+c) with a, b, and c being the respective areas of the subtriangles (P, B, C), (P, C, A) and (P, A, B), we obtain the following relation:

[0070] [Math.l] ÔP = &Æ -F kP.ÔB L fcCÔC

[0071] Thus, as shown in [Fig.9], knowing the triplet (kA, kB, kC) and applying this relation, it is possible to calculate the position of a point P in any triangle and thus define a natural bijection between two triangles (A0, BO, CO) and (Al, B1, Cl).

[0072] We then obtain the real coordinates (xO, yO) of point PO and the coordinates (xl, yl) of its antecedent (point PI) by the following equations:

[0073] [Math.2] xO = kA xx (AO) + kB xx (BO) + kC xx(C0)

[0074] [Math.3] yO = kA xy (A0) + kB xy (BO) + kC xy(C0)

[0075] [Math.4] ,xl = kA xx{ Al) + kB xx(Bl) + kC x ,x(Cl)

[0076] [Math.5] yl = kA xy (Al) + kB xy (Bl) + kC xy(Cl)

[0077] This step is repeated for all the triangles of the Delaunay triangulation in order to generate the rectified reference image, and the resulting transformation algorithm.

[0078] The following sub-step SS8 of step S3 of compensating for the actual deformation of the printed panels to be cut then consists of applying the transformation algorithm thus obtained to the geometry of the parts to be cut.

[0079] The pieces to be cut are then cut according to their geometry modified during step S4.

[0080] It will be noted that this step S4 of cutting the parts can be implemented either as a real image of the printed panels is acquired (sub-step SS1), or once the entire real image of the printed panels has been acquired.

Claims

1. Claims Method of cutting out placements of pieces in panels of flexible material packaged in rolls or coupons and on each of which the same patterned design has been printed, the method comprising: - an initial stage (IS) of digital characterization of the printed panels including: • the definition (SS1) of a reference plane for the printed panels; • the acquisition (SS2) of a real image of a reference panel; • matching (SS3) characteristic points of the reference plane with corresponding characteristic points of the real image of the reference panel; and • obtaining (SS4) a reference image of the reference panel with the coordinates of the characteristic points; - a step (S2) of developing theoretical placements of pieces to be cut in the printed panels using the reference image and in relation to characteristic points thereof; - a step (S3) of compensating for the actual deformation of the printed panels to be cut, comprising: • the acquisition (SS5) of a real image of the printed panels to be cut with detection of their characteristic points; • matching (SS6) the characteristic points of the reference plane with those of the real image of the printed panels; • the determination (SS7) of an algorithm for transforming the reference image into the real image of the printed panels; and • the application (SS8) of the transformation algorithm to the geometry of the parts to be cut from the theoretical placements; - a step (S4) of cutting the placement of parts according to their new geometry.

2. A method according to claim 1, wherein the reference image is obtained by rectifying the real image of the reference panel and its characteristic points.

3. A method according to claim 2, wherein defining a reference plane of the printed panels comprises identifying within the reference panel notable graphic elements of the design printed on the panel and associating these notable graphic elements with control points with the acquisition of their geometric coordinates.

4. A method according to claim 3, wherein the control points of the reference plane are constituted by: intersection points of straight line segments, end points of straight line segments, or points on the outline of geometric figures of the design printed on the panel.

5. A method according to one of claims 3 and 4, wherein the matching of characteristic points of the reference plane comprises the translation of the control points of the reference plane to match them with the remarkable graphic elements which they designate in the real image of the reference panel.

6. Method according to any one of claims 1 to 5, in which the determination of a transformation algorithm comprises the development of two triangular meshes of identical structure from the control points of the reference plane on the one hand, and from the remarkable graphic elements which they designate in the real image of the printed panel, on the other hand.

7. The method of claim 6, wherein the determination of a transformation algorithm is performed pixel by pixel for each triangle of the triangular mesh associated with the real image of the reference panel.

8. Method according to one of claims 6 and 7, in which the triangular meshes are produced by applying a Delaunay triangulation.

9. Method according to claim 1, wherein the reference image is directly transmitted with its characteristic points.

10. A method according to any one of claims 1 to 9, wherein acquiring a real image of the printed panels to be cut further comprises acquiring a thumbnail associated with each detected characteristic point.

11. A method according to any one of claims 1 to 10, wherein the design printed on the panels is a non-repeating pattern design.

12. A method according to any one of claims 1 to 11, wherein the step of compensating for the actual deformation of the printed panels to be cut is carried out as an actual image of the printed panels is acquired.

13. A method according to any one of claims 1 to 11, wherein the step of compensating for the actual deformation of the printed panels to be cut is implemented after the entire actual image of the printed panels has been acquired.

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