FR3088112A1 - Method for detecting the angular position of a hollow body by taking at least two images of a neck of the hollow body - Google Patents

Abstract

The invention relates to a method for detecting the angular orientation of hollow bodies (10) of thermoplastic material comprising a neck (12) of determined main axis (A) which is equipped with a mark (20), the method comprising: a first step (E1) of taking at least one image (P) of the neck (12) from a shooting position and in a shooting axis (B) both determined with respect to the hollow body ( 10); - a second step (E2) of processing the at least one image (P) to detect the angular position of the marker (20); characterized in that the step (E1) of taking at least one image consists in taking at least two images (P1, P2, P3, P4) of the outer periphery of the neck (12) from shooting positions offset from the main axis (A) of the neck (12). Figure for the abstract: Figure 4

Description

Description

Title of the invention: Method for detecting the angular position of a hollow body by taking at least two images of a neck of the hollow body

Technical Field of the Invention The invention relates to a method for detecting the angular orientation of hollow bodies made of thermoplastic material, in particular of preforms and / or containers, comprising a neck of determined main axis which is equipped a benchmark for determining its angular orientation, the method comprising:

- A first step of taking at least one image of the neck of the hollow body;

- A second step of processing the at least one image to detect the angular position of the marker.

Technical background [0004] It is known to produce containers from thermoplastic material by blowing preforms, the body of which is previously heated. The preforms have a neck which is already molded to its final shape and which is therefore intended to remain unchanged during the production of the container.

[0005] Mass production of such containers is carried out by means of a blowing station which is equipped with numerous blowing molds. The large number of molds makes it possible to produce the containers at a high rate, for example greater than or equal to 50,000 bottles per hour. The molds are for example carried by a carousel which rotates so that the preforms are blown one after the other at a high rate during their movement between a point of introduction corresponding to the introduction of the preforms into an associated mold, and a point of release corresponding to the ejection of the containers formed outside the molds.

The containers thus obtained are received on leaving the mold by means of gripping a transfer wheel so that they are routed to another device via, for example, a conveyor. The next station is, for example, a container filling station or a container labeling or marking station.

It is sometimes necessary to modify the angular orientation of the preforms or containers during their movement.

Such modification of the angular orientation is for example necessary when the containers have at least one section which is not axisymmetric with respect to the axis of the neck.

To obtain such non-axisymmetric containers, the preforms are generally heated preferentially on certain parts, according to a process generally called preferential heating. The preforms are then received in molds with a well-defined orientation to match the heating profile of the bodies with the imprint of the non-axisymmetric container to be obtained.

In addition, the non-axisymmetric containers thus obtained must be presented with a well-defined orientation in a downstream labeling device so that a label is applied to a receiving face reserved for this purpose on the non-axisymmetric container.

Such a modification is also necessary in other configurations, for example on certain containers, axisymmetric or not, which are intended to be equipped with spray guns which must be oriented correctly relative to a label of the container.

The stations are generally themselves equipped with means of transporting the containers, such as carousels. The modification of the angular orientation of the container can also take place directly on these means of transport, and not only on means of transfer between two stations.

To allow the correct orientation of the preforms and / or containers, it is known to equip the neck of the preforms with a mark which allows their angular orientation to be achieved around the axis of the neck relative to a support. Since the neck retains its shape during the process for producing the container, this mark remains usable to allow the orientation of the finished container around the axis of its neck.

Such a mark is for example formed by a notch made in a collar flange, or by a lug formed in a groove located at the base of the collar.

This mark makes it possible to determine the angular orientation of the preform or of the container with respect to its support, and optionally to modify the angular orientation of the preform or of the support to bring the mark to a reference position determined with respect to to support.

In the following description, the terms hollow body will be used either as a preform or as a finished container.

To know the angular position of the mark relative to the support of the hollow body, it has already been proposed to use an image capture device whose shooting axis coincides with the axis of the neck of the preform. The image capture device thus makes it possible to take a single image of the collar in order to detect a mark formed by a notch made in the periphery of the collar.

However, such a device does not allow to see a mark which would be likely to be hidden by other elements of the preform on the image. Thus, the image does not make it possible to see a mark formed by a lug located in a groove made in one face of the neck parallel to its axis.

In addition, some containers require the use of preforms without flanges. In this case, the preform is provided with a stopper carrying a removable collar to allow its handling during the process for producing the final container. However, such a collar is capable of moving relative to the hollow body and therefore cannot be used to bear the mark. The mark is then necessarily carried by a face of the neck parallel to its axis. Such a mark is difficult to detect by the device of the prior art, or even completely hidden by the collar which risks being interposed between the field of vision of the image capture device and the mark.

Summary of the invention The invention provides a method for detecting the angular orientation of hollow bodies made of thermoplastic material, in particular of preforms, comprising a neck of determined main axis which is equipped with a mark enabling its angular orientation, the method comprising:

- A first step of taking at least one image of the neck of the hollow body by means of at least one image capture device from a shooting position and in a shooting axis both determined with respect to the hollow body;

- A second step of processing the at least one image to detect the angular position of the marker relative to the shooting axis of the at least one image capturing device.

The method according to the teachings of the invention is characterized in that the step of taking at least one image consists in taking at least two images of the outer periphery of the neck from shooting positions offset by relative to the main axis of the neck, the shooting positions being distributed around the main axis of the neck so that all of the images reveal the entire outer periphery of the neck.

According to other characteristics of the process carried out according to the teachings of the invention:

- The step of taking at least one image consists in taking at least three images of the outer periphery of the neck from shooting positions eccentric relative to the main axis of the neck, the shooting positions of view being distributed around the main axis of the neck so that all of the images reveal the entire outer periphery of the neck;

- When taking each image, the associated shooting axes intersect at a common point of intersection located on the main axis of the neck generally at the neck;

- Each shooting axis forms a zenith angle of between 20 ° and 160 ° relative to the main axis of the neck, preferably between 20 ° and 45 °, for example 25 °; - During the step of taking at least image, four images of the neck are taken from four distinct shooting positions relative to the hollow body;

- the at least two images are taken simultaneously, each by an associated image capture device;

- The hollow body is transported along a determined path relative to a fixed frame, the image capture devices being fixed relative to the frame, and the images being taken during the passage of the hollow body in at minus a specific point on the route;

- The hollow body is transported along a determined path relative to a fixed frame, the image capturing devices being moved jointly with the hollow body during its transport.

The invention also relates to a device for implementing the method carried out according to the teachings of the invention, the device being characterized in that it comprises:

- A support which is intended to receive a hollow body and which is mounted movable along a determined path;

- A shooting unit formed by at least two image capturing devices which are arranged regularly along the same circle, their shooting axes being directed towards a common point of central intersection located substantially along a central axis of the circle orthogonal to the plane of the circle, the common point of intersection being located on the path of the main axis of the neck of the hollow bodies.

According to other characteristics of the device produced according to the teachings of the invention:

- The shooting assembly includes at least three image capture devices;

- The shooting set includes four image capture devices;

- the shooting assembly is movable together with the support;

- The shooting assembly is fixed relative to a frame intended to be fixed relative to the ground during the implementation of the method.

Brief description of the figures Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

[Fig. 1] Figure 1 is a side view of a shooting assembly for implementing the method of the invention for detecting the angular orientation of a hollow body which comprises several devices for capturing images offset from the axis of a neck of the hollow body.

[Fig-2] Figure 2 is a detail view in perspective on a larger scale of the neck of the hollow body of Figure 1 which is equipped with a mark to detect its angular position.

[Fig.3] Figure 3 is a view similar to that of Figure 2 which shows an alternative embodiment of the neck of Figure 2 in which the reference is arranged in a groove of the neck.

[Fig.4] Figure 4 is a perspective view which shows the shooting assembly of Figure 1.

[Fig.5] Figure 5 is an elevational view which shows the shooting assembly of Figure 1.

[Fig.6] Figure 6 shows an image of a neck of a hollow body taken from a first shooting position along a first associated shooting axis.

[Fig.7] Figure 7 shows an image of the neck of the hollow body of Figure 6 taken from a second shooting position along a second associated shooting axis.

[Fig.8] Figure 8 shows an image of the neck of the hollow body of Figure 6 taken from a third shooting position along a third associated shooting axis.

[Fig.9] Figure 9 shows an image of the neck of the hollow body of Figure 6 taken from a fourth shooting position along a fourth associated shooting axis.

[Fig.10] Figure 10 is a top view which shows a device implementing the method of the invention comprising a transport device and a set of image taking fixed relative to a chassis of the device transport.

[Fig. 11] FIG. 11 is a side view which represents the shooting assembly of the device of FIG. 10.

[Fig. 12] Figure 12 is a view similar to that of Figure 11 which shows an alternative embodiment of the device for implementing the method of the invention in which the shooting assembly is movable together with a support of the body hollow.

[Fig. 13] FIG. 13 is a perspective view which represents the shooting assembly according to a second embodiment of the invention in which the shooting assembly comprises a single image capture device rotatably mounted around an axis coinciding with a main axis of the neck of the hollow body.

[Fig. 14] Figure 14 is a schematic view from above which shows a variant of the second embodiment of the invention in which several shooting devices are distributed along a path of the hollow body.

[Fig. 15] Figure 15 is a block diagram which represents the detection method carried out according to the teachings of the invention.

Detailed description of the invention In the following description, elements having an identical structure or similar functions will be designated by the same references.

In the following description, we will adopt non-limiting longitudinal orientations arranged parallel to the direction of movement of the hollow bodies, vertical, arranged parallel to the axis of the neck of the hollow bodies, and transverse indicated by the trihedron L , V, T of the figures. The vertical orientation is used as a purely geometric reference without relation to the direction of gravity.

There is shown in Figure 1 a hollow body 10, which is here formed by a preform. The hollow body 10 is made of thermoplastic material, here polyethylene terephthalate (PET). The hollow body 10 in the preform state is conventionally obtained by injection molding.

In general, such a hollow body 10 has a neck 12, shown here at the top of Figure 1, and a body 14, shown at the bottom.

The neck 12 has a generally cylindrical shape of revolution with a vertical axis A. The neck 12 has a cylindrical outer face, which can be equipped with a thread as is the case here. A free circular edge 15 of the upper end of the neck 12, also called the flange, delimits an opening which makes it possible to open the hollow body 10 towards the outside.

The neck 12 may also have a groove 16 formed in the base of the external face. Such a groove 16 is generally intended to receive a so-called tamper-evident ring which is linked in a breakable manner to a plug intended to equip the final container.

The neck 12 here has a collar 18 which extends radially projecting outwards just below the groove 16.

Alternatively, the flange 18 may be arranged elsewhere than at the base of the neck 12, for example at the level of the free circular edge 15.

According to yet another variant, the support face is attached to the preform, for example by means of a plug.

Here being a preform, the body 14 of the hollow body 10 has a substantially axisymmetric shape around the main axis A of the neck 12. The body 14 is here formed into an elongated tube along the axis A main having a closed lower end and which is open at its upper end by the neck 12.

The neck 12 is intended to keep its shape whatever the manufacturing step in which the hollow body 10 is located. Thus, the neck 12 has the same shape as the hollow body 10 is in the preform state or as a finished container.

The neck 12 is equipped with at least one marker 20, here a single marker 20, which makes it possible to determine the angular position of the hollow body 10 around its axis A. In the example shown in FIG. 2, the item 20 is here formed by a notch made in the periphery of the collar 18.

As a variant shown in FIG. 3, the reference 20 is formed by a lug produced in the groove 16.

According to a variant not shown, the reference 20 can be formed by any mark, excess material or removal of visible material in a visible angular position around the neck 12.

The invention provides a method for automatically detecting the angular orientation of hollow bodies 10 made of thermoplastic material, relative to a support 22.

The method has a first step El of taking at least one image which consists in taking at least one image P of the neck 12 of the hollow body 10 by means of at least one device 24 for capturing images from a shooting position and in a shooting axis B both determined with respect to the hollow body 10, and more particularly with respect to a support 22 by which the hollow body 10 is fixedly carried.

Each capture device 24 is for example formed by a digital camera or by a digital camera.

Thereafter, the references of each device 24 for capturing images and their shooting axis B will be designated by their respective reference followed by a number making it possible to distinguish them from each other.

The axes B for taking pictures of each of the devices 24-1, 24-2, 24-3, 24-4 for capturing images intersect at a common point S of intersection with the main axis A of the neck 12 generally at the neck 12 of the hollow body 10 at the time of taking the image.

More particularly, a zenith angle φ is defined below as being the angle formed between the axis B of the photograph relative to the main axis A of the neck 12 in an axial plane when the axis B the angle of view is inclined relative to the main axis A of the neck 12 around an axis orthogonal to said axial plane as shown in FIGS. 1 and 4.

We also define a longitude angle 0 which corresponds to the angle formed between an axial plane containing the shooting axis B and the main axis A of the neck 12 and an axial plane containing the main axis A of the neck 12. For example, in FIG. 5, the zenith angle φ between the axis B3 of shooting and the axis B4 of shooting is shown.

According to the teachings of the invention, the step El of taking at least one image consists in taking at least two images PI, P2, P3, P4 of angular sectors of the outer periphery of the neck 12 of the hollow body 10 from eccentric shooting positions relative to the main axis A of the neck 12.

Advantageously, the step E1 of taking at least one image consists in taking at least three images PI, P2, P3, P4 of angular sectors of the external periphery of the neck 12 of the hollow body 10 from taken positions. of view eccentric with respect to the main axis A of the neck 12. This makes it possible to obtain a better estimate of the angular position of the reference 20 because the images then have overlapping zones. Thus, even when the reference frame is located at the limit of an image, it appears more in the center on another image, which makes it possible to improve the precision of the estimation of its angular position.

The axes Bl, B2, B3, B4 for taking pictures are referenced B followed by a number each corresponding to one shooting position. The shooting positions are distributed regularly around the main axis A of the neck 12 so that the set of images PI, P2, P3, P4 combined reveals the entire circumference of the neck 12 of the hollow body 10. More particularly , the shooting axes Bl, B2, B3, B4 are arranged at the same longitude angle 0 relative to each other.

In addition, as shown in Figures 1 and 4, each axis Bl, B2, B3, B4 of shooting forms a zenith angle φ between 20 ° and 160 ° relative to the main axis A of the neck 12 Preferably, the zenith angle φ is between 20 ° and 45 °, for example 25 °. This zenith angle φ is preferably the same for all the shooting axes B1, B2, B3, B4.

During an image processing step E2, the images PI, P2, P3, P4 of said neck 12 are processed to detect the angular position of the marker 20 with respect to the axis B of which the image is taken. at least one device 24 for capturing images. The image processing PI, P2, P3, P4 is for example carried out automatically by an image processing means such as image recognition software. The processing means thus make it possible to separate the images P3, P4 on which the reference 20 does not appear in order to be able to analyze the images P1, P2 on which the reference 20 appears.

During this second step E2 of image processing, the processing means make it possible to detect the mark 20 on at least one of the images P1, P2, as shown in FIGS. 6 and 7, for example by means of a shape recognition software. The processing means also make it possible to estimate the longitude angle between the benchmark 20 thus recognized and the corresponding shooting axis B.

This is for example taking for reference the center of the free circular edge 15. For this purpose, each device 24-1, 24-2, 24-3, 24-4 is positioned so as to capture the entire free circular edge 15 on the image PI, P2, P3, P4, as shown in Figures 6 to 9.

It is thus possible to determine the angle 01, 02 of longitude between the shooting axis Bl, B2 according to which said image P1, P2 has been taken and the reference frame 20.

Certain angular sectors of the neck 12 appear to overlap on two images P1, P2, P3, P4. The assembly of images P1, P2, P3, P4 makes it possible to reconstruct a complete peripheral view of the external face of the neck 12 in the manner of a photographic panorama.

To carry out this second step, the images PI, P2, P3, P4 taken by the devices 24 for capturing images are automatically transmitted to an electronic control unit 26, shown diagrammatically in FIG. 1, which is equipped with image processing means.

Advantageously, during the step El of taking at least one image, four images PI, P2, P3, P4 of the neck 12 of the hollow body 10 are taken from four distinct shooting positions relative to the body hollow 10, as shown in FIGS. 6 to

9. This allows the entire peripheral surface of the cervix to be redundantly covered

12. Indeed, the angular sector represented on each image PI, P2, P3, P4 is entirely overlapping on two adjacent images PI, P2, P3, P4. The mark 20 therefore appears on two images P1, P2 taken during the first step El of taking at least one image. It is thus possible to accurately evaluate the angular position 0 of the reference frame 20 by carrying out two estimates of the angles 01, 02 between the reference frame 20 and each of the two corresponding shooting axes Bl, B2, as illustrated in FIGS. 6 and 7.

To implement this method, there is provided a device 28 comprising at least one support 22 for receiving the hollow body 10 leaving visible the mark 20 of the neck 12. This is for example a notch on the periphery from which the flange 18 rests as shown in FIG. 10, or else a clamp which grasps the hollow body 10 under the flange 18. The hollow body 10 is intended to remain fixed relative to the support 22 during the whole process. Thus, the support serves as a fixed geometric reference to determine the angular orientation of the reference 20 around the main axis A of the neck 12.

As regards a method intended to be applied to hollow bodies 10 circulating in a container manufacturing installation, the support 22 is advantageously mounted to be movable along a determined path coinciding with a path for producing the bodies hollow 10. As shown in FIG. 10, the support 22 is for example carried by a device 30 for transporting a hollow body 10 here formed by a transport wheel. In a variant not shown, the transport device and formed by a transport chain. The transport device 30 advantageously comprises several supports 22 to enable several hollow bodies 10 to be transported in file.

The transport device 30 rests on the ground by means of a frame 32 fixed relative to the ground. As this is a transport wheel, the transport device 30 is mounted for rotation relative to the chassis 32 about a vertical axis. The support 22 is thus movable relative to the fixed frame 32 so as to transport the hollow bodies 10 along the determined path in a longitudinal direction as indicated by the arrow F in FIG. 11.

According to a first embodiment of the invention shown in Figures 10 to 11, the at least two shots are taken simultaneously, each by a device 24-1, 24-2, 24-3, 24-4 associated image capture. This embodiment makes it possible to obtain images PI, P2, P3, P4 precisely positioned with respect to the main axis A of the neck 12.

To this end, the device 28 further comprises a set 34 for taking pictures formed by at least two devices 24-1, 24-2, 24-3, 24-4 for capturing images which are arranged. at regular angles of longitude 0 from each other along the same circle 36, as shown in FIG. 5. Advantageously, the shooting assembly 34 comprises at least three devices 24-1, 24-2, 24 -3.24-4 for capturing images which are arranged at regular angles of longitude 0 from each other along the same circle 36 to allow a better estimate of the angular position of the marker 20 to be obtained as previously explained.

The axes Bl, B2, B3, B4 for taking pictures of each of the devices 24-1, 24-2, 24-3, 24-4 for capturing images are directed towards a common point S of intersection central located substantially along a central vertical axis C of the circle 36. The central axis C is of course orthogonal to the plane in which the circle 36 extends. The first step El of taking at least one image is thus performed when the main axis A of the neck 12 is in coincidence with the central axis C of the shooting assembly.

When four images PI, P2, P3, P4 are taken during the first step El of taking at least one image, the assembly 34 comprises four devices 24-1, 24-2, 24-3, 24 -4 for capturing view images arranged at a longitude angle of 90 ° relative to each other.

The set 34 of shooting advantageously comprises a light source 38 which allows to illuminate the entire periphery of the neck 12 to improve the quality of the image obtained. This is an annular light stroke which is for example formed by several light-emitting diodes which are arranged on a ring centered on the axis C of the circle 36. The devices 24-1, 24-2, 24-3, 24-4 for image capture are here arranged above the annular light source 38 so that the axes Bl, B2, B3, B4 of shots pass inside the ring formed by the source 38 bright. This makes it possible to arrange the light source 38 as close as possible to the neck 12. The light source 38 is of course arranged above the neck 12 so as not to interfere with the movement of the hollow body 10.

The devices 24-1, 24-2, 24-3, 24-4 for image capture are here fixed relative to the chassis 32. The common point S of intersection of the axes Bl, B2, B3, B4 of shooting is arranged on the path of the main axis A of the neck 12 of the circulating hollow bodies 10. PI, P2, P3, P4 images are taken when passing the main axis

A of the neck 12 in coincidence with the common point S of intersection.

For example, the passage of each support 22 automatically triggers the taking of an image as a function of an operating parameter of the transport device.

Alternatively, the transport device comprises a sensor which is capable of detecting the passage of a hollow body 10 at the common point of intersection.

This first embodiment is particularly advantageous because it allows the use of a single set 34 of image capture to detect on the fly the orientation of each hollow body 10 supported by the transport device 30.

According to a variant of this first embodiment of the invention shown in Figure 12, the devices 24-1, 24-2, 24-3, 24-4 for capturing images are moved together with the body hollow 10 during transport. The image capture assembly 34 is more particularly on-board while traveling with the support 22. Thus, the image capture assembly 34 is movable jointly with the support 22.

This variant makes it possible to benefit from more time to carry out the detection method according to the invention. However, it is necessary to have as many assemblies 34 for taking images as there are supports 22 on the transport device 30.

According to a second embodiment of the invention, the images PI, P2, P3, P4 taken during the first step E1 of taking at least one image are taken successively by means of one or more devices 24-1, 24-2, 24-3, 24-4 image capture.

According to the example shown in Figure 13, the image capture device 24 is mounted movable, for example on an arm 40 rotatable around the central axis C. When the support 22 is movable, the arm 40 is mounted movable jointly with the transport device 30 so that its axis of rotation is in coincidence with the main axis A of the neck 12 of the hollow body 10 supported by the support 22 The arm 40 is controlled, for example by means of an electric motor, between different angular positions which make it possible to bring the device 24 for capturing images successively to each shooting position from which it takes the PI images, P2, P3, P4.

According to a variant of this second embodiment shown in FIG. 14, several devices 24-1, 24-2, 24-3, 24-4 for capturing images are arranged along the path of the support 22, each in an associated shooting position when the main axis A of the neck 12 of the hollow body 10 supported by the support 22 crosses the axis Bl, B2, B3, B4 for shooting each of the devices 24- 1, 24-2, 24-3, 24-4 for image capture.

Whatever the embodiment used, during the first step El of taking at least one image, at least two images PI, P2, P3, P4 of the periphery of the neck 12 of the hollow body 10 supported by the support are taken by the device (s) 24-1, 24-2, 24-3, 24-4 for image capture. In the example shown in FIGS. 6 to 9, four images PI, P2, P3, P4 are taken with an angular offset corresponding to a longitude angle of 90 °. As shown in Figures 6 and 7, the reference 20 is thus always visible on two images P1, P2 simultaneously.

During the second step E2 of image processing, the processing means make it possible to locate the reference 20 on each of these two images P1, P2, then by measuring their angle 01, 02 of longitude around the circle formed by the free circular edge 15 of the neck 12 relative to the axis B1, B2 for taking a picture, it is possible to precisely locate the angular position of the reference 20 around the main axis A of the neck 12 relative to the support 22.

Thus, in a next step, it is possible to control the pivoting of the hollow bodies 10 about their main axis A relative to the support 22 to bring them into the same angular reference position, for example by means of movable arms or by means of friction rollers which drive the hollow body 10 in rotation.

For each of the embodiments of the invention, the zenith angle φ is advantageously adjustable for each of the devices 24-1, 24-2, 24-3, 24-4 for capturing images. It is thus possible to adapt the image-taking assembly to necks 12 of different dimensions.

The invention advantageously makes it possible to obtain a total vision of the external periphery of the neck 12 without blind spots. This notably makes it possible to successfully carry out the angular detection of the neck 12 by means of marks 20 of various shapes which can be arranged indifferently at any point of the neck 12. It is in particular possible to detect marks 20 which are arranged in a peripheral groove 16 of the neck 12, or alternatively marks 20 formed by marks made on the external cylindrical wall of the neck 12.

Claims (1)

Claims [Claim 1] Method for detecting the angular orientation of hollow bodies (10) of thermoplastic material, in particular of preforms and / or containers, comprising a neck (12) of determined main axis (A) which is equipped with at least one mark ( 20) making it possible to determine its angular orientation, the method comprising: - A first step (El) of taking at least one image (P) of the neck (12) of the hollow body (10) by means of at least one device (24) for capturing images from a position of capture of view and in a shooting axis (B) both determined with respect to the hollow body (10); - a second step (E2) of processing the at least one image (P) to detect the angular position of the reference (20) relative to the axis (B) of shooting of the at least one device ( 24) image capture; characterized in that the step (El) of taking at least one image consists in taking at least two images (PI, P2, P3, P4) of the outer periphery of the neck (12) from shooting positions offset from the main axis (A) of the neck (12), the shooting positions being distributed around the main axis (A) of the neck so that all of the images (PI, P2, P3 , P4) shows the entire outer periphery of the neck (12). [Claim 2] Method according to the preceding claim, characterized in that the step of taking at least one image consists in taking at least three images (Pl, P2, P3, P4) of the external periphery of the neck (12) from positions of shooting offset from the main axis (A) of the neck (12), the shooting positions being distributed around the main axis (A) of the neck so that all of the images (PI, P2, P3, P4) reveal the entire outer periphery of the neck (12). [Claim 3] Method according to the preceding claim, characterized in that at the time of the taking of each image (PI, P2, P3, P4), the axes (Bl, B2, B3, B4) of associated shooting are intersecting at a point (S) common intersection located on the main axis (A) of the neck (12) generally at the level of the neck (12). [Claim 4] Method according to any one of the preceding claims, characterized in that each shooting axis (Bl, B2, B3, B4) forms a zenith angle (φ) of between 20 ° and 160 ° relative to the axis ( A) main of the neck, preferably between 20 ° and 45 °, for example 25 °. [Claim 5] Method according to any one of the preceding claims, characterized in that during the step (El) of taking at least one image, four images (PI, P2, P3, P4) of the neck (12) are taken from four distinct shooting positions relative to the body hollow (10). [Claim 6] Method according to any one of the preceding claims, characterized in that the at least two images (PI, P2, P3, P4) are taken simultaneously, each by a device (24-1, 24-2, 24-3, 24 -4) associated image capture. [Claim 7] Method according to any one of the preceding claims, characterized in that the hollow body (10) is transported along a determined path with respect to a fixed frame (32), the devices (24-1, 24-2, 24-3, 24-4) of image capture being fixed relative to the frame (32), and the images (PI, P2, P3, P4) being taken during the passage of the hollow body (10) in at least one determined points of the route. [Claim 8] Method according to any one of Claims 1 to 6, characterized in that the hollow body (10) is transported along a determined path with respect to a fixed frame (32), the devices (24-1, 24- 2, 24-3, 24-4) of image capture being moved together with the hollow body (10) during its transport. [Claim 9] Device (28) for implementing the method produced according to any one of claims 7 or 8, characterized in that it comprises: - a support (22) which is intended to receive a hollow body (10) and which is mounted movable along a determined path; - a set (34) of shooting formed by at least two devices (24-1, 24-2, 24-3, 24-4) for capturing images which are arranged regularly along the same circle (36), their axes (Bl, B2, B3, B4) of shooting being directed towards a common point (S) of central intersection situated substantially along a central axis (C) of the orthogonal circle (36) in the plane of the circle (36), the common point (S) of intersection being located on the path of the main axis (A) of the neck (12) of the hollow bodies (10). [Claim 10] Device (28) according to the preceding claim, characterized in that the assembly (34) for taking pictures comprises at least three devices (24-1, 24-2, 24-3, 24-4) for capturing images . [Claim 11] Device (28) according to the preceding claim, characterized in that the assembly (34) for taking pictures comprises four devices (24-1, 24-2, 24-3, 24-4) for capturing images. [Claim 12] Device (28) according to any one of claims 9 to 11, characterized in that the shooting assembly (34) is movable jointly with the support (22). [Claim 13] Device (28) according to any one of claims 9 to 11, characterized in that the set (34) of shooting is fixed relative to a frame (32) intended to be fixed relative to the soil during the implementation of the process.