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 out piece patterns in rolls or sheets of flexible material panels Technical field

[0001] The invention relates to the general field of cutting out piece patterns in rolls or sheets of flexible material panels, each of which has been printed with the same pattern.

[0002] An application field of the invention is in particular that of the luxury fashion 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 event shows (for example during "Fashion Week"), which they then send to be produced by their subcontractors responsible for industrializing the presented models.

[0004] The subcontractors then produce a prototype of the garment, which is checked and then approved by the brand according to demanding specifications and quality criteria. The brand can then place an order for a certain number of pieces with 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 high labor costs and delays.

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

[0007] To produce an article or garment in such a material, it is therefore necessary to cut 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 on the joining 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 they pass under the scanner of the cutting machine. Indeed, material deformation problems can take several forms and be due to several factors. In particular, the deformation of the material may be related to printing (subject to heat and processing agent constraints), roll packaging of the material (non-uniform winding constraint), and placement (synchronization between the placement carried out by the feeder and the cutter conveyor causing creases).

[0009] Furthermore, deformation can take several forms. It can be a shrinkage of the fabric, a localized deformation of the fabric (the fabric is unstable, having shrunk or stretched in areas of non-homogeneous material), a regular deformation of the fabric (the fabric is twisted uniformly), or an irregular deformation (the fabric is twisted heterogeneously both in the direction of the material and in the direction of the roll). It should be noted that these different forms of deformation can appear independently or cumulatively on the same fabric.

[0010] It is known to attempt to compensate for these deformations of the panels to be cut by allowing the operator to manually adjust the material placed on the machine in order to align it as closely as possible with the cutting conveyor. However, this deformation compensation process has the disadvantage of being manual and operator-dependent, which poses a productivity and labor problem, significantly increasing production costs. Description of the invention

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

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

[0013] The method according to the invention is remarkable in that it offers a compensation solution that is based entirely on a software solution that does not require manual intervention from operators. More specifically, the compensation solution of the method according to the invention makes it possible, by comparing 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 for the printed panels may advantageously include the identification within the reference panel of notable graphic elements of the design printed on the panel and the association of these notable graphic elements with control points with the acquisition of their geometric coordinates.

[0016] The control points of the reference plane can consist of: points of intersection of line segments, endpoints of line segments, or points on the contour of geometric figures of the drawing printed on the panel.

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

[0018] The determination of a transformation algorithm advantageously includes 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 includes the acquisition of a thumbnail associated with each detected characteristic point.

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

[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.1] Fig.1 is a flowchart showing the main steps of the cutting process according to the invention.

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

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

[0028] [Fig.4] to [Fig.7] Figures 4 to 7 illustrate different stages 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 process 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 process according to the invention. Description of the implementation methods

[0031] The invention relates to the automatic cutting of pieces from panels of flexible material (for example, silk twill or organza fabric) which are supplied in rolls or pieces and on each of which the same design has been printed. patterned design.

[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 material advance: a supply module positioned at one end of the cutting table, an acquisition module for scanning the material spread out on the cutting table, a cutting module, and a module for unloading the cut parts which is positioned at the other end of the cutting table.

[0033] By "panel" we mean here a rectangular area of ​​the flexible material on which a single design (with repeating or non-repeating patterns) has been printed and in which a single set of pieces (intended for the making of one or more garments) is to be cut.

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

[0035] As represented by [Fig. 1], the method according to the invention for cutting part placements in such panels comprises four main steps, namely: an initial step S1 of digital characterization of the printed panels allowing 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 in order to modify the geometry of the parts to be cut from the theoretical placements, and a step S4 of cutting the part placements according to their new geometry.

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

[0037] This initial step Sla aims to obtain a reference image of a reference panel.

[0038] The term "reference image" here refers to a plane of the reference panel indicating the position (in a geometric coordinate system linked to the panel) of prominent graphic elements of the design printed on the panels. More precisely, these prominent graphic elements of the design printed on the panel are 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 / supplier order, or analog measurements carried out on a sample panel (case described below).

[0040] Figure 2 shows an example of a fabric panel on which a non-repeating pattern design has been printed. To define the reference plane, the operator first defines the geometric limits of the panel (for example, a square with sides of 140 cm), then marks control points within the pattern of the panel by acquiring their geometric coordinates in a geometric coordinate system linked to the panel.

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

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

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

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

[0045] The next substep SS2 consists of acquiring an actual 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 for export to a characterization application.

[0047] Figure 3 shows an example of obtaining a real image of a reference panel corresponding to the fabric panel of Figure 2. In this figure, it can be seen that the fabric has undergone deformations whose consequences on the pattern are visible (some lines of the design are no longer straight but curved).

[0048] The next substep SS3 consists for the operator in matching the characteristic points of the previously defined reference plane with corresponding characteristic points of the actual image of the reference panel.

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

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

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

[0052] Fig. 6 shows how the control points P are adjusted to correspond with the notable graphic elements 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 (substep 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 process).

[0055] As is known, these placements are notably developed taking into account the constraints of connections between the pieces of clothing.

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

[0057] Initially, the flexible material to be cut is positioned at the infeed of the cutting machine and passes under its acquisition module (i.e., scanner). The acquisition module acquires a real image of the first panel to be cut (substep 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 substep SS4) with those of the real image of the scanned printed panel (substep 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 next substep SS7 consists of determining an algorithm for transforming the reference image into the actual image of the printed panels.

[0061] According to one embodiment of this substep 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 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 control point clouds, these two meshes being of identical structure and corresponding respectively to the control point cloud in the frame of the reference image and to the control point cloud in the frame of the actual 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 constructed by applying a Delaunay triangulation known to those skilled in the art. The purpose of such a triangulation is to maximize the smallest angle among 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 rectification, triangle to triangle, between the triangular mesh MO covering the reference image and the triangular mesh Ml covering the actual 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 traversing 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 (i.e. reciprocal) transformation 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 (Al, Bl, Cl), the color to be assigned to PO is determined by calculating the reciprocal position of PO in the real image.

[0068] Let (xO, yO) be the real coordinates of point PO located at the center of pixel 10 of image 10, 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 triangle T1 corresponds to the position PO relative to triangle T0. This bijective function uses the concept 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 sub-triangles (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 triangles of the Delaunay triangulation in order to generate the rectified reference image, and the resulting transformation algorithm.

[0078] The next substep SS8 of step S3 for compensating 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 parts to be cut are then cut according to their modified geometry during step S4.

[0080] It should 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. Demands A method for cutting out placements of parts in panels of flexible material supplied in rolls or coupons, each of which has been printed with the same patterned design, the method comprising: - an initial step (IS) of digital characterization of printed panels including: • the definition (SS1) of a reference plane for printed panels; • the acquisition (SS2) of a real image of a reference panel; • the mapping (SS3) of characteristic points of the reference plane with corresponding characteristic points of the actual 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 parts to be cut in the printed panels using the reference image and in relation to characteristic points of it; - a step (S3) for 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; • the matching (SS6) of the characteristic points of the reference plane with those of the actual image of the printed panels; • the determination (SS7) of an algorithm for transforming the reference image into the actual 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 placements of parts according to their new geometry.

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

3. A method according to claim 2, wherein the definition of a reference plane for the printed panels includes the identification within the reference panel of notable graphic elements of the design printed on the panel and the association of 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 line segments, endpoints of line segments, or points on the contour of geometric figures of the design printed on the panel.

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

6. A method according to any one of claims 1 to 5, wherein 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 notable graphic elements that they designate in the actual image of the printed panel on the other hand.

7. A method according to claim 6, wherein the determination of a transformation algorithm is carried out pixel by pixel for each triangle of the triangular mesh associated with the actual image of the reference panel.

8. A method according to any one of claims 6 and 7, wherein the triangular meshes are developed by applying a Delaunay triangulation.

9. A 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 the acquisition of an actual image of the printed panels to be cut further includes the acquisition of 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 implemented 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 once the entire actual image of the printed panels has been acquired.

Images