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WO2012053977A1 - Appareil et procédés pour obtenir une image de paquet de produits - Google Patents

Appareil et procédés pour obtenir une image de paquet de produits Download PDF

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Publication number
WO2012053977A1
WO2012053977A1 PCT/SG2011/000363 SG2011000363W WO2012053977A1 WO 2012053977 A1 WO2012053977 A1 WO 2012053977A1 SG 2011000363 W SG2011000363 W SG 2011000363W WO 2012053977 A1 WO2012053977 A1 WO 2012053977A1
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WO
WIPO (PCT)
Prior art keywords
laser
image
goods package
laser beam
acquiring
Prior art date
Application number
PCT/SG2011/000363
Other languages
English (en)
Inventor
Dmitry Nechiporenko
Andrew Conley
Original Assignee
Azimuth Intellectual Products Pte Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Azimuth Intellectual Products Pte Ltd filed Critical Azimuth Intellectual Products Pte Ltd
Publication of WO2012053977A1 publication Critical patent/WO2012053977A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/8806—Specially adapted optical and illumination features
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V10/00—Arrangements for image or video recognition or understanding
    • G06V10/10—Image acquisition
    • G06V10/12—Details of acquisition arrangements; Constructional details thereof
    • G06V10/14—Optical characteristics of the device performing the acquisition or on the illumination arrangements
    • G06V10/145—Illumination specially adapted for pattern recognition, e.g. using gratings
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V2201/00—Indexing scheme relating to image or video recognition or understanding
    • G06V2201/06—Recognition of objects for industrial automation

Definitions

  • laser illumination is an attractive proposition for a number of reasons.
  • lasing devices tend to be compact in size, do not require excessive amounts of energy from their power sources, and are a good solution in situations where the illumination light must be polarised.
  • This is a particularly advantageous feature in situations where the light source must penetrate a material such as a transparent or partially transparent film thereby allowing illumination of an object under the material.
  • details of the object under the film may be read by a reading device or, say, have an image of the object captured by an imaging device such as a camera and the use of polarised light in such circumstances leads to a reduction in excessive glare from the film.
  • speckle is a random intensity pattern produced by the mutual interference of a set of wave fronts. It is observed when radio waves are scattered. It is a result of the interference of many waves, having different phases, which add together to produce a resultant wave whose amplitude, and therefore intensity, varies randomly.
  • speckle is a random pattern created when a laser beam is scattered off a rough surface. Speckle is not normally an issue in light beams of low coherence - made up of many different wavelengths -- because the speckle patterns produced by individual wavelengths have different dimensions and will normally average one another out.
  • Speckle effect may become so severe, that it causes distortion of the image acquired by the imaging device (as high-contrast, large speckle "kernels" are very difficult to distinguish from target items - i.e. those items which it is desired to capture an image of - like text, labels, barcodes, etc.), thereby leading to spurious results and possibly rendering any results unusable.
  • One approach as utilised by the system disclosed in United States Patent Application Publication 2010/0080253 Al, provides an imaging system which includes a plurality of laser sources configured to produce a plurality of light beams.
  • One or more optical alignment devices orient the light beams into a collimated light beam.
  • a light modulator modulates the collimated light beam such that images can be presented on a display surface.
  • Speckle is reduced with an optical feedback device that causes the laser sources to operate in a coherent collapsed state. Examples of optical feedback devices include partially reflective mirrors and beam splitter-mirror combinations.
  • an apparatus where the laser devices are arranged to project an illumination laser at a projection angle to illuminate a surface of a goods package (or other object), where the projection angle is oriented at the predetermined angle relative to a principal axis of view of a linescan camera, offers a convenient and cost-effective solution to reduce speckle effect.
  • an imaging device for capturing an image of an object having a rough surface may capture an image with reduced interference and noise caused by speckle reflection from the rough surface.
  • provision of an array of low-intensity lasers to project a composite laser beam to illuminate a portion of a rough surface of the goods package allows for a uniform, or substantially uniform, laser beam of resultant higher intensity.
  • individual laser devices which, respectively, project laser beams onto adjacent portions of the object allows for a composite laser beam of higher intensity to be produced, without the attendant disadvantage of increased speckle caused by the use of a high-powered emitter.
  • acceptable results for reduced speckle can be achieved using low- intensity lasers of around, say, 5 mW or 7 mW, to produce a composite laser beam with an intensity level of the order of 20,000 lux or above for image acquisition of a large load, such as a pallet of goods.
  • a substantially uniform beam may be achieved using smaller, individual low-intensity lasers.
  • the term "substantially uniform" in the context of a composite laser beam includes a laser beam which has no readily perceivable bright or dark spots when viewed by an imaging device such as a linescan camera.
  • a relatively inexpensive source of illumination is provided, having a uniform or substantially uniform beam width up to the typical width of pallet, say around 1.4m, with intensity of the order of 20,000 lux or more, with reduced reflection and low speckle.
  • Figure 1 is a series of block diagrams illustrating views of a first apparatus for acquiring an image of a surface of a goods package
  • Figure 2 is a block diagram illustrating an elevational view of a second apparatus for acquiring an image of a surface of a goods package
  • Figure 3 is a series of block diagrams illustrating a plan view and enlarged part thereof of a third apparatus for acquiring an image of a surface of a goods package.
  • Figure 4 is a series of block diagrams illustrating exemplary laser arrays for use with the apparatus of any of Figures 1 to 3.
  • Apparatus 100 comprises a linescan camera 102 capable of capturing an image in an optical plane 104. That is, the field of view of linescan camera 102 is in the optical plane 104.
  • Apparatus 100 also comprises a first laser device 106a which, in this example, is arranged to emitter a laser beam in an axis which is coplanar with optical plane 104.
  • apparatus 100 also has a second laser device 106b, but this is omitted from the view of Figure 1A for the sake of simplicity. However, this can be seen in Figure IB which will be discussed shortly.
  • Linescan camera 102 and the or each laser devices 106a, 106b are mounted on supports 108 mounted on base 110 disposed on floor surface 112.
  • the linescan camera 102 is arranged for movement in a movement plane 114, as will be explained shortly.
  • Apparatus 100 is provided to capture an image of goods package 118 disposed upon a pallet 116 which, in turn, is also disposed upon floor surface 112.
  • goods package 118 has a surface 120, the surface which apparatus 100 is to acquire an image of.
  • Goods package 118 has a material 122 thereon which is partially transparent to laser light.
  • One exemplary material 122 is shrink wrap film such as is commonly used for the wrapping of goods packages or stacks of goods packages. It will be appreciated that, in the view of Figure 1A, the spacing between shrink wrap 122 and goods package 118 has been exaggerated for the sake of illustration and, in practice, one would expect shrink wrap 122 to be wrapped tightly around goods package 118.
  • apparatus 100 and goods package 118 is illustrated in plan view.
  • both the laser devices 106a and 106b are illustrated.
  • Linescan camera 102 and laser devices 106a, 106b are retained on a frame support 111.
  • optical plane (field of view) 104 of linescan camera 102 can be seen in plan view Figure IB, it can be seen that the field of view fans out from the aperture 103 of linescan camera 102.
  • the optical plane is a principal axis of view 124 of optical plane 104 and can be thought of as a line extending along the major axis of linescan camera 102 about which the field of view is symmetrical in the optical plane 104.
  • principal axis of view 124 is parallel to a normal N of surface 120 of goods package 118.
  • Laser device 106b projects a laser beam 126.
  • laser beam 126 is a line laser.
  • the line laser may have a Gaussian intensity distribution in which case line 126 is representative of the centre of intensity of the beam, but with laser light being projected on the sides of line 126 as well. This provides the technical benefit that, with a fan angle about 15 degrees, a relatively uniform image may be acquired.
  • Laser 126 is projected at a projection angle 128 from the principal axis of view 124 of linescan camera 102.
  • the angle 128 of projection of laser beam 126 is such that its reflections 130 as reflected from material 122 reflect at an angle away from the field of view and sensor matrix/aperture 103 of linescan camera 102.
  • laser device 106a projects a laser beam 132 also at an angle 128a from principal axis of view 124.
  • reflections 134 of laser beam 132 are also reflected from material 122 at an angle away from the field of view and sensor matrix/aperture 103 of linescan camera 102.
  • any direct reflections of the laser beams 126, 132 do not cause any interference in the acquisition by linescan camera 102 of an image of surface 120 of goods package 118.
  • each of laser devices 106a 106b may take several variant forms. For instance, in the example of Figure IB, only a single laser beam is illustrated for the sake of simplicity but it will be appreciated that the or each laser device 106a, 106b may emit more than one laser beam projected generally parallel with laser beam lines 126, 132. In such a situation, each of the laser beams 126, 132 can be considered representative of the plural laser beams.
  • speckle may be caused by the projection of a laseron to any roughened surface. In the context of goods packages/pallet loads, these are often wrapped in a material 122 such as shrink wrap film..
  • the surface (for example, the external surface facing the camera device) of the shrink wrap film may be considered a surface of the goods package.
  • the manner of the shrink wrapping of the film results in a surface which is not substantially flat and, therefore, is susceptible to causing speckling when the laser light is shone thereon.
  • Figure 1 illustrates an apparatus 100 for acquiring an image of a surface 120 of a goods package 118, the surface being a rough surface, in the context that it is capable of causing speckle.
  • Apparatus 100 comprises a linescan camera 102 for acquiring the image of the surface 120 of goods package 118 on an optical plane 104 having a principal axis of view 124.
  • a (the or each) laser device 106a, 106b projects a laser beam 132, 126 at a projection angle 128, 128a thereby to illuminate the surface 120 of goods package 118 on the optical plane (i.e. the field of view of laser camera 102 is incident upon surface 120 of goods package 118 in the optical plane 104).
  • Projection angle 128, 128a is oriented at a
  • linescan camera 102 is arranged for movement in a movement plate 114 to acquire the image of the surface 120 of the goods package 118 and does so one line at a time. The result is a complete hi-resolution (for example, approximately 160 Mpixel) image.
  • Linescan camera 102 is arranged to move vertically in plane 114.
  • linescan camera 102 is mounted for linear movement on supports 108 which may comprise of linear actuators, having suitable drivers as will be known to the skilled person, and these are arranged upon a support base 110.
  • a suitable linescan camera is one which is set to grab about 6-10 lines per mm with a field of view 104 of a line being 1 pixel thick and 8000 pixel wide, but other, for example higher, resolutions are contemplated.
  • the or each laser device 106a, 106b shares, as mentioned above, the support framework 111 upon which both the laser devices 106a, 106b and linescan camera 102 are supported.
  • operation of the linear actuators may be such that the linescan camera 102 and the or each laser device 106a, 106b is moved in the movement plane 114.
  • the or each laser device 106a, 106b is arranged to project the laser beam 132, 126 in the optical plane 104.
  • the or each laser beam 132, 126 is projected in the optical plane 104 of linescan camera 102; the or each laser beam 132, 126 is coplanar with the optical plane 104. While it is desirable that the or each laser beam 132, 126 is incident upon surface 120 to illuminate the surface 120 of goods package 118 for linescan camera 102 to acquire an image thereof, it is not essential that the or each laser beam 132, 126 actually be projected in a plane which is coplanar with optical plane 104.
  • An alternative arrangement is illustrated in Figure 2.
  • a projection angle 128 may be selected dependent upon certain design parameters of the apparatus 100. For instance, if a "working distance" between linescan camera 102 and surface 120 is 1.8 m, then a suitable angle of projection of the laser beam (or a principal axis of a composite laser beam) is 65.2°.
  • principal axis of view 124 of linescan camera 102 is coaxial with a normal N of surface 120, it will be appreciated that this is not essential.
  • principal axis 124 may be arranged at an angle to normal IM or surface 120.
  • the or each laser beam 132, 126 is still projected at an angle 128 from principal axis of view 124.
  • any reflections of the laser light on shrink wrap 122 are reflected away from the sensor matrix of linescan camera 102.
  • the linescan camera and the or each laser device are moved while the goods package remains stationary.
  • the camera may be moved and the laser device held stationery, as long as the laser beam I capable of moving to illuminate the field of view of the linescan camera as it scans.
  • the techniques disclosed herein have broader application than that and may also be used in a conveyor application wherein the linescan camera (and perhaps the laser device) are stationary and goods are moved past the linescan camera (and perhaps the laser device) on a conveyor system. What is significant is that the relative movement is effected between the goods package and the linescan camera.
  • any goods package may have a material thereon -- such as a reflective label - which may cause glare/ reflection and/or speckle, and which might otherwise cause interference in the image acquisition device when acquiring the image of the goods package.
  • a material thereon such as a reflective label - which may cause glare/ reflection and/or speckle, and which might otherwise cause interference in the image acquisition device when acquiring the image of the goods package.
  • a goods package stationary (upon a pallet load or similar) and the linescan camera arranged to move to acquire the image.
  • a goods package has a high likelihood of being wrapped in a reflective and speckle-inducing material such as shrink wrap.
  • a shrink-wrapped film may be considered a particularly rough surface of the goods package in the context of laser illumination and speckle.
  • apparatus 200 comprises a linescan camera 102 having an optical plane 104 (the plane in which the camera's field of view is) and one or more laser devices 106.
  • linescan camera 102 and the or each laser device 106 are mounted for linear movement on supports 108 which may comprise of linear actuators with suitable supports 108 arranged upon a support base 110.
  • apparatus 200 operates to capture an image of a surface 120 of goods package 118, which, in this example, is wrapped in shrink wrap film 122.
  • the or each laser device 106 is not mounted to project the or each laser beam 204 in the optical plane.
  • the or each laser device 106 is mounted above a linescan camera 102 but arranged to project laser beam 204 at an angle 206 from the horizontal plane (in the example of Figure 2 the optical plane 104 is in the horizontal plane).
  • laser beam 204 is co-incident on surface 120 of goods package 118.
  • the field of view 104 of linescan camera 102 is illuminated by laser beam 204 as it moves in movement plane 114 to capture the image of surface 120.
  • laser beam 204 is also projected at a projection angle 128 relative to the principal axis of view of optical plane 104 to ensure that any reflections (for example, caused by speckling of the laser on the surface of material 122) reflect away from the sensing matrix of linescan camera 102, as is illustrated in Figure IB.
  • FIG 3 a third apparatus for acquiring an image of a rough surface of a goods package is illustrated in plan view in Figure 3A, and an enlarged part thereof is illustrated in Figure 3B.
  • Apparatus 300 comprises a linescan camera 302 for acquiring the image of the surface 304 of goods package 306.
  • Goods package 306 has thereon a material 316 -- such as shrink wrap film.
  • Goods package 306 is disposed upon pallet 318.
  • Apparatus 300 further comprises one or more laser devices 308 comprising an array 310 of low-intensity line lasers, 310a, 310b, etc, for projecting a composite laser beam 312 to illuminate a portion 314 of the surface 304 of goods package 306.
  • Suitable values of power for the low-intensity lasers include powers in the range of 5 mW to 7 mW, although other power values are contemplated.
  • Array 310 comprises a first low-intensity line laser 310a for projecting a first laser beam 312a on to a first portion 314a (see Figure 3B) and a second low-intensity line laser 310b for projecting a second laser beam 312b onto a second portion 314b (see Figure 3B) of the surface 304.
  • second portion 314b is adjacent first portion 314a, thereby to reduce the speckling 318 caused by reflections of laser light from the material 316.
  • FIG. 4A An example of a laser array 400 is shown in Figure 4A.
  • the lasers 402a, 402b, ... 402n are arranged in a linear array.
  • Such an arrangement facilitates simple projection of the lasers in the optical plane 104, as illustrated in Figure 1A, assuming with lasers are oriented in a plane normal to axis 404.
  • the lasers 402a, 402b, ... 402n are not arranged on a common line 404, and as such, may be considered to be in a non-linear array.
  • the lasers 402a, 402b, ... 402n are arranged such that their individual beams are incident upon the surface of the goods package to project a composite laser line. That is, the individual lasers produce a composite beam and, in a manner similar to that of Figure 2, are co-incident upon the field of view/optical plane 104 of linescan camera 102.
  • FIG. 4C Another non-linear array 400 is illustrated in Figure 4C were the individual lasers 402a, 402b, ... 402n are arranged in an irregular array and, as in Figure 4B, the individual beams are arranged to be incident upon the surface of the goods package to project a composite laser line.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Multimedia (AREA)
  • Theoretical Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Artificial Intelligence (AREA)
  • Chemical & Material Sciences (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
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Abstract

L'invention concerne un appareil et un procédé permettant d'obtenir une image d'une surface rugueuse d'un paquet de produits. Une caméra à balayage linéaire obtient l'image sur un plan optique ayant un axe de vue principal. Un dispositif laser projette un faisceau laser selon un angle de projection, éclairant ainsi la surface sur le plan optique. L'angle de projection est orienté suivant un angle prédéterminé par rapport à l'axe de vue principal. Un second appareil comprend une caméra à balayage linéaire permettant d'obtenir une image d'une surface d'un paquet de produits. Un dispositif laser comprenant un réseau de lasers faible intensité projette un faisceau laser composite pour éclairer une partie de la surface. Ledit réseau comprend un premier laser faible intensité pour projeter un premier faisceau laser sur une première partie de la surface et le second laser faible intensité pour projeter un second faisceau laser sur la seconde partie de la surface. La caméra à balayage linéaire est déplacée dans plan de déplacement p0our obtenir l'image.
PCT/SG2011/000363 2010-10-19 2011-10-18 Appareil et procédés pour obtenir une image de paquet de produits WO2012053977A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SG201007674-3 2010-10-19
SG2010076743A SG180036A1 (en) 2010-10-19 2010-10-19 Apparatus and methods for acquiring an image of a goods package

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WO2012053977A1 true WO2012053977A1 (fr) 2012-04-26

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PCT/SG2011/000363 WO2012053977A1 (fr) 2010-10-19 2011-10-18 Appareil et procédés pour obtenir une image de paquet de produits

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993016353A1 (fr) * 1992-02-18 1993-08-19 British Steel Plc Procede et dispositif servant a mesurer la forme de la surface d'un objet
DE4222908A1 (de) * 1992-07-11 1994-01-13 Licentia Gmbh Verfahren zur Lokalisierung von Adreßbereichen auf Postgut
WO1996034253A1 (fr) * 1995-04-27 1996-10-31 View Engineering, Inc. Procede d'imagerie tridimensionnelle, utilisant la triangulation, a l'aide d'un faisceau explorateur angle d'energie rayonnante et dispositif correspondant
US20070075853A1 (en) * 2005-10-04 2007-04-05 Griffin Dennis P Cargo sensing apparatus for a cargo container

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993016353A1 (fr) * 1992-02-18 1993-08-19 British Steel Plc Procede et dispositif servant a mesurer la forme de la surface d'un objet
DE4222908A1 (de) * 1992-07-11 1994-01-13 Licentia Gmbh Verfahren zur Lokalisierung von Adreßbereichen auf Postgut
WO1996034253A1 (fr) * 1995-04-27 1996-10-31 View Engineering, Inc. Procede d'imagerie tridimensionnelle, utilisant la triangulation, a l'aide d'un faisceau explorateur angle d'energie rayonnante et dispositif correspondant
US20070075853A1 (en) * 2005-10-04 2007-04-05 Griffin Dennis P Cargo sensing apparatus for a cargo container

Also Published As

Publication number Publication date
SG180036A1 (en) 2012-05-30

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