WO2010072912A1 - Device for three-dimensional scanning with dense reconstruction - Google Patents

Device for three-dimensional scanning with dense reconstruction Download PDF

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Publication number
WO2010072912A1
WO2010072912A1 PCT/FR2009/001428 FR2009001428W WO2010072912A1 WO 2010072912 A1 WO2010072912 A1 WO 2010072912A1 FR 2009001428 W FR2009001428 W FR 2009001428W WO 2010072912 A1 WO2010072912 A1 WO 2010072912A1
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WIPO (PCT)
Prior art keywords
axis
camera
projection
image
axial
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PCT/FR2009/001428
Other languages
French (fr)
Inventor
Vincent Lemonde
Ludovic Brethes
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Noomeo
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Publication of WO2010072912A1 publication Critical patent/WO2010072912A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
    • G01B11/2509—Color coding
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
    • G01B11/2545—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object with one projection direction and several detection directions, e.g. stereo

Definitions

  • the invention relates to the construction of non-contact synthetic images from physical three-dimensional objects. This technique is commonly called three-dimensional scanning, or, according to the English terminology, 3D scanning.
  • Such a tool generally comprises one or more scanners, portable or not, performing an acquisition of the topography of the object along one or more orientations, this topography being then exploited to perform a three-dimensional synthesis reconstruction of the object in the CAD environment.
  • the scanning which consists in projecting on the object a linear image (generally a plane light brush generated by means of a laser source) and scanning the surface of the object by means of this line, the successive distortions of which allow, as and when, a reconstruction of the entire illuminated side, and
  • the one-shot capture which consists in projecting onto the object, in a specific manner, a structured image containing a predetermined pattern whose general distortion, with respect to its projection on a plane, is analyzed point by point to allow the reconstruction of the illuminated side.
  • This technique has the advantage of being precise but it takes time however (several seconds for each scan) and requires that the object be perfectly immobile for the duration of the projection. It is understood that this technique is difficult to apply to biometrics (except for limited parts of the human body).
  • the use of the laser is delicate, and can even be dangerous if one must use it to scan the human face. This is why the one-shot technique is currently considered to be more promising because of the speed, greater than that of scanning, with which acquisition can be achieved.
  • This phenomenon occurs especially when a relief on the surface of the object to be scanned projects in its vicinity, under the effect of the light coming from the projector, a shadow whose image taken by the capture apparatus appears as a black spot and is therefore unusable for the reconstruction of the corresponding surface portion.
  • the system of document FR 2 842 591 in which the object to be digitized is illuminated with oblique incident light, illustrates this problem.
  • This phenomenon also occurs when a relief has an invisible hidden face for the capture device. It should be noted that stereovision, in which two capture devices simultaneously point towards the object, does not necessarily overcome the occultation phenomena.
  • the problem of occultations is circumvented by taking several successive shots by varying the angle of incidence of the projection, so as to minimize the hidden areas.
  • this solution not only strikes the capture times, because of the multiple shots for the same surface, but also the processing times, because of the redundancy of the reconstruction calculations for the unobstructed areas, and the necessity to provide, in the holes corresponding to the occult areas, sewing operations of reconstructed surface portions. These sewing operations are inherently difficult to program and can lead to surface aberrations that complicate modeling.
  • the invention aims in particular to remedy the difficulties described above, by proposing a one-shot scanning system, which is freed from the occultation phenomena as much as possible and allows a fast and reliable acquisition of the data necessary for the reconstruction. .
  • the invention proposes a device for constructing an image of synthesis of a three-dimensional surface of a physical object, this device comprising: a projector arranged to project, along an optical axis of projection, an image of a pattern comprising a plurality of points of light intensities and / or predetermined colors, the projector being arranged so that the image of the pattern is sharp in a predetermined image plane perpendicular to the projection axis; - An axial camera pointing in the direction of the image plane and having an axial axis of axial sight, the axial camera being positioned so that its axis of sight forms with the axis of projection a zero angle.
  • a remote camera pointing in the direction of the image plane and having a remote optical axis of view, this camera being positioned so that its axis of sight forms with the projection axis a non-zero angle.
  • FIG. 1 is a perspective view illustrating a three-dimensional scanning device comprising a connected capture apparatus to a computer
  • Fig. 2 is a sectional elevational view showing the capture apparatus of Fig. 1
  • FIG. 3 is a schematic side view illustrating the main optical components of the apparatus of FIG. 2, placed in a shooting situation of an object
  • Figure 4 is a schematic side view showing the fields of view of the cameras and their planes objects
  • - Figure 5 is a schematic perspective view showing the components shown in Figure 3
  • Figure 6 is a view similar to Figure 5, according to another angle of view
  • FIG. 7 is a perspective view showing the illuminated surface of the object, located in the field of view of the off-axis camera
  • Figure 8 is a perspective view showing the portion of the illuminated surface of the object, located in the field of view of the axial camera placed virtually in the axis of projection
  • FIG. 9 is a plan view, in the axis of the capture apparatus, of the speckle projected onto one face of the object of FIG.
  • FIG. 1 shows a contactless scanning device 1 for constructing an image of synthesis of a three-dimensional surface of a physical object 2.
  • this object 2 is represented in the form of a vase but it could be any other object having one or more three-dimensional surfaces to be digitized, these surfaces being, in practice, in relief, that is to say non-planar.
  • the scanning device 1 comprises an optical capture apparatus 3, provided with a portable casing 4 equipped with a handle 5 allowing its capture and manipulation.
  • the handle 5 carries, on a front face, a manual release 6 whose operation commands the shooting.
  • the scanning device 1 also comprises a unit 7 for processing the images captured by the device 3, in the form of a processor on which is implemented a software application for constructing the synthesis images from the captured images.
  • the processor may be embedded in the apparatus 3 or, as illustrated in FIG. 1, relocated by being integrated in a computer 8 connected to the capture apparatus 3 via a wireless communication interface or wired, for example in the form of a computer bus 9 USB type.
  • the capture apparatus 3 comprises, mounted in the housing 4: a light projector 10; an axial optical acquisition device 1 1, of the camera type
  • a remote optical acquisition device 12 of the same type as the axial optical acquisition device 1 1; a system 13 of optical sighting.
  • optical acquisition devices 11, 12 are cameras which, if necessary, can be used as cameras.
  • the projector 10 comprises a light source 14, a focusing optics 15 and a pattern 16 interposed between the light source 14 and the focusing optics 15.
  • the light source 14 is preferably a non-coherent source of white light, in particular of the filament or halogen type, or also of the diode (LED) type.
  • the focusing optics shown diagrammatically in FIGS. 3, 5 and 6 by a single converging lens, define a main optical axis 17 passing through the light source 14. This optical axis 17 defines an optical projection axis of the capture apparatus 3.
  • the pattern 16 defines a speckle comprising a multitude of points of light intensities (contrast) and / or predetermined colors.
  • the target 16 is in the form of a translucent or transparent plate (glass or plastic), square or rectangular, of the slide type, on which the speckle is printed by a conventional method (transfer, offset, screen printing, flexography, laser, inkjet, microlithography, etc.).
  • the pattern 16 is disposed between the light source 14 and the optic 15, on the axis 17 of projection, that is to say perpendicularly to the projection axis 17 and so that it passes through the center of the target 16 (defined in this case by the crossing of its diagonals).
  • the target 16 is placed at a predetermined distance from the optics 15 of which it constitutes an object plane, so that the image of the pattern is clear. in a predetermined image plane perpendicular to the projection axis 17.
  • the example given below provides preferred numerical values.
  • the camera 1 1 axial comprises a focusing optics 18, shown schematically in Figures 3, 5 and 6 by a single converging lens, and defining an optical axis 19 axial sight.
  • the camera 1 1 axial further comprises a photosensitive sensor 20, for example CCD type, which is in the form of a square or rectangular plate placed, facing the optics 18 of focus, on the optical axis 19 of axial view, that is to say perpendicular to it and so that the axis 19 passes through the center of the sensor 20 (defined in this case by the crossing of its diagonals).
  • a photosensitive sensor 20 for example CCD type, which is in the form of a square or rectangular plate placed, facing the optics 18 of focus, on the optical axis 19 of axial view, that is to say perpendicular to it and so that the axis 19 passes through the center of the sensor 20 (defined in this case by the crossing of its diagonals).
  • the camera 1 1 axial is oriented so as to point in the direction of the image plane of the projector 10, being positioned so that its axis of sight 19 forms with the axis 17 projection a virtually zero angle.
  • the camera 1 1 axial is positioned so that its axis 19 of sight is perpendicular to the axis 17 of projection and concurrent with it, while being located in a median plane of the target 16.
  • the plan containing the projection axis 17 and the axis 19 of axial aiming is called the aiming plane.
  • An optical splitter 21 is disposed on the projection axis 17 at its intersection with the optical axis 19 of axial aiming.
  • This optical separator 21 can be in the form of a thin or thick blade, or in the form of a prism.
  • the optical separator 21 is in the form of a blade 21 inclined by 45 ° with respect to the axis 17 of projection (and therefore also with respect to the axis 19 of sight of the axial camera). It has two opposite planar main faces, namely a rear face 22, turned on the side of the projector 10, and a front face 23, turned towards the camera 1 1 axial.
  • the rear face 22 is designed to transmit along the axis 17 of projection the incident light from the projector 10.
  • the front face 23 is semi-reflective, that is to say that it is intended to transmit according to the projection axis 17 incident light from the projector 10, but to reflect, along the axis 19 of axial view and to the camera 1 1 axial, the reflected light that reaches him, along the axis 17 of projection, the object 2 illuminated.
  • the separating blade 21 is arranged in such a way that the projection axis 17 and the axial viewing axis 19 are concurrent on the semi-reflecting front face 23, and more precisely in the center thereof, defined by the cross-section of its diagonals.
  • the camera 1 1 axial forms a virtual camera located on the axis 17 of projection.
  • the sensor 20 is placed at a predetermined distance from the optics 18, in an image plane situated at a predetermined distance from it, depending on its focal length (see the example below) and such that the corresponding object plane 24 at this image plane is substantially coincident with the image plane of the projector 10.
  • this virtual camera is located in front of the projector 10 rather than behind it, that is to say that the length of the optical path separating the object plane 24 from the camera 1 1 axial (i.e. the image plane of the projector 10) and the image plane thereof (in which the sensor 20 extends) is less than the length of the optical path separating the object plane from the projector 10 (in which extends the target 16) and the image plane thereof.
  • this arrangement results in the fact that the distance from the axial camera 11 to the separator blade 21 is less than the distance of the projector 10 to the separating blade 21. This makes it possible to use a sensor 20 of reasonable size (and therefore of reasonable cost), the field of view of which is strictly included in the image of the speckle.
  • the remote camera 12 is equipped with a focusing optics 25, shown diagrammatically in FIGS. 3, 5 and 6 by a single convergent lens, and defining an optical axis 26 for remote viewing.
  • the remote camera 12 furthermore comprises a photosensitive sensor 27, for example of the CCD type, which is in the form of a square or rectangular plate placed, facing the focusing optics 25, on the optical axis 26 of aiming. deported, that is to say perpendicular to it and so that the axis 26 passes through the center of the sensor 27 (defined in this case by the crossing of its diagonals).
  • a photosensitive sensor 27 for example of the CCD type, which is in the form of a square or rectangular plate placed, facing the focusing optics 25, on the optical axis 26 of aiming. deported, that is to say perpendicular to it and so that the axis 26 passes through the center of the sensor 27 (defined in this case by the crossing of its diagonals).
  • the remote camera 12 is oriented so as to point in the direction of the image plane of the projector 10, being positioned so that its viewing axis 26 forms with the projection axis 17 a non-zero angle ⁇ (see the numerical example of FIG. -after) and is located in the plane of sight (in other words, the projection axis 17, the axial viewing axis 19 and the remote viewing axis 26 are coplanar).
  • the sensor 27 is placed at a predetermined distance from the optic 25, in an image plane situated at a predetermined distance from it, depending on its focal length (see the example below) and such that: the center of the plane object 28 corresponding to this image plane is located on the axis 17 projection;
  • the object plane 24 of the camera 1 1 axial is included in the field of view of the sensor 27 of the camera 12 remote.
  • This configuration which imposes a shift of the object plane 28 of the camera 12 offset with respect to the object plane 24 of the axial camera 1 1, parallel to the projection axis 17, constitutes the best compromise between a good sharpness and maximum coverage of the fields of view of the two sensors 20, 27.
  • the remote camera 12 is positioned in such a way that the length of the optical path separating the object plane 28 from the remote camera 12 (whose intersection with the image plane of the projector 10 is a line perpendicular to the viewing plane and passing through by the center of the image plane of the projector 10) and the image plane thereof (in which the sensor 27 extends) is less than the length of the optical path separating the object plane from the projector 10 (in which the 16) and the image plane of it.
  • this arrangement allows to use a sensor 27 of reasonable size (and therefore reasonable cost), whose field of view is strictly included in the image of speckling.
  • the sighting system 13 is arranged to allow, prior to the shooting, a positioning of the apparatus 3 at a distance from the object 2 such that the projection thereon of the speckle (i.e. 16) be as clean as possible.
  • This sighting system 13 comprises two laser pointers 29, mounted in the housing 4 of the apparatus, designed to emit each, when the trigger 6 is depressed, a ray or linear light beam 31, 32 producing, on any illuminated surface, a light spot 33 substantially punctual.
  • the pointers 29, 30 are angularly positioned in the casing 4 so that the radii 31, 32 emitted intersect at a point of intersection located on the projection axis 17, substantially in the image plane of the projector 10.
  • the preferred dimensioning makes it possible to project in the image plane of the projector 10, located at 481 mm from the optical 15 thereof (this value can easily be deduced from the values provided by the relationship of thin lens conjugation) a sharp image of the speckled ( Figure 9), whose large side measures approximately 260 mm, this image being strictly included in the fields of the sensors 20, 27.
  • the capture apparatus 3 is positioned facing the object 2, facing a surface thereof that it is desired to digitize.
  • the trigger 6 is then depressed, which causes the ignition of the pointers 29, 30 lasers and the emission of their respective beams 31, 32.
  • the distance from the apparatus 3 to the object 2 is then adjusted so that the intersection of the beams 31, 32 laser is located on the surface of the object 2, that is, that is, so that only one light spot 33 appears on the surface of the object 2.
  • the point of the surface of the object corresponding to the spot 33 is then substantially in the image plane of the projector 10, which minimizes the blur that will affect the image of speckled projected on object 2.
  • the release of the trigger 6 causes the ignition of the light source 14 and the projection of speckled on the object 2.
  • the triggering mechanism may be of the flash type, that is to say that the projection of speckling and shooting are performed punctually and simultaneously, or of delayed type, that is to say that the taking of The view can be triggered - automatically or manually - for a period of time during which the projection is done continuously. Burst operation can also be provided in which several shots are taken successively at predetermined time intervals.
  • the incident white light emitted by the light source 14 first passes through the target 16, is focused by the optics 15 and then passes without reflection the separating plate 21. This light illuminates - with projection of the target 16 - the object to be digitized.
  • This reflected light undergoes a second reflection at right angles to the front face 23 of the splitter plate 21 towards the camera January 1.
  • the twice reflected light is focused by the optics 18 of the camera 1 1 axial and hits the sensor 20, which acquires a first deformed image of the speckled projected on the object 2.
  • the camera 1 1 axial axis 19 axial sight is virtually coincident with the axis 17 projection. In other words, although the camera 1 1 axial is not physically disposed on the axis 17 of projection, it is in this axis 17 to the extent that everything happens as if the light reflected by the object 2 and striking the sensor 20 had not undergone any deviation.
  • the interposition of the splitter blade 21 makes it possible, in practice, to avoid the concealment of the projector 10 that would be caused by the physical assembly of the camera 1 1 axial on the axis 17 of projection in front of the projector 10.
  • the images thus captured are transferred to the processing unit 7, which operates the three-dimensional reconstruction of the illuminated surface of the object 2 on the triple base of these two deformed images of the speckle, and the undistorted image of the speckle such as that projected on a plane confused with the image plane of the projector 10.
  • the processing unit 7 performs a mapping of the image of the deformed speckle from the remote camera 12 with the image of the deformed speckle from the axial camera 11.
  • This mapping can be performed for each point of the speckle, or in a selection of predetermined points, performed within the undistorted image.
  • the accuracy of the construction depends on the accuracy of the sensor 27.
  • the preferred dimensioning proposed above provides, for a sensor 27 comprising of the order of 1 million pixels, a precision of the order of one tenth of mm, sufficient to build an image of acceptable synthesis of any type of object whose size is on a human scale.
  • the processing unit 7 performs, from this mapping, a first reconstruction of the surface to be digitized by means of a triangulation calculation, so as to obtain a cloud of points.
  • the next step consists in completing and refining the cloud of points thus constructed by matching, for all the points of the cloud or for a selection of points, each point of the undistorted speckle with the corresponding point of the deformed speckle.
  • this pairing can be achieved by correlation, that is to say by successive approaches within zones which, although having local disparities, appear similar in neighboring regions of the two images.
  • the processing unit 7 measures for this point the deviation undergone, that is to say, the shift in the image of the deformed speckle of the position of the point relative to its position in the image of undistorted speckle.
  • the processing unit decomposes this deviation into a horizontal component (parallel to the abscissa axis) and a vertical component (parallel to the ordinate axis).
  • the processing unit 7 derives thereafter, by a calculation of triangulation carried out within the processing unit from the data coming from the sensor, at least the depth coordinate of the point of the image of the deformed speckle corresponding to the point selected in the image of undistorted mouchetis.
  • occultations can occur in the deformed image, in particular due to reliefs on the surface of the object 2.
  • the processing unit 7 repeats the operations of comparison, of pairing (that is to say of correlation), of measuring the deviation of the selected points and of calculating the depth coordinate of each point for the image. deformed mouchetis as captured and transmitted by the camera 1 1 axial. Some of the points, already calculated from the deformed image from the remote camera 12, are thus recalculated and are therefore redundant. This redundancy is used by the processing unit 7 to refine the three-dimensional position of these points from the double measurement.
  • the processing unit 7 reconstructs a dense synthetic image of the illuminated surface of the object 2, at least in the portion at the intersection of the fields of view of the two cameras 1 1, 12.
  • the configuration of the device makes it possible to avoid occultation phenomena. It is therefore not necessary to take several shots of the same surface to obtain a complete reconstruction thereof, for the benefit of simplicity and speed of execution.
  • the two cameras complement each other: the camera 1 1 axial allows not only to refine the measurements from the remote camera 12, but also to complete the areas possibly obscured, while the camera 12 remote allows to obtain a reconstruction of the surface in the vicinity of the projection axis, where the weakness of the solid angle of the field of view of the camera 1 1 axial does not provide sufficient accuracy of the measurements.
  • the shooting operations can be repeated at will on different sides of the object, so as to obtain a complete reconstruction thereof.
  • Classic sewing operations will be planned to join the different reconstructed surfaces.

Abstract

The invention relates to a device (1) for constructing a synthetic image of the three-dimensional surface of a physical object (2), wherein said device includes: a projector (10) arranged to project, along an optical projection axis (17), an image of a pattern including a plurality of points having predetermined light intensities and/or colours, the projector (10) being arranged so that the image of the pattern is clear in a predetermined image plane perpendicular to the projection axis (17); an axial camera (11) oriented towards the image plane and having an optical axial visual axis (19), the axial camera (11) being positioned so that the visual axis (19) thereof defines an angle (α) with the projection axis equal to zero; and an offset camera (12) oriented towards the image plane and having an offset optical visual axis (26), said camera (12) being positioned so that the visual axis (26) thereof defines an angle with the projection axis (17) not equal to zero.

Description

DISPOSITIF DE NUMERISATION TRIDIMENSIONNELLE A RECONSTRUCTION DENSE DENSE RECONSTRUCTION THREE-DIMENSIONAL SCANNING DEVICE
L'invention a trait à la construction d'images de synthèses sans contact à partir d'objets tridimensionnels physiques. Cette technique est couramment appelée numérisation tridimensionnelle, ou encore, suivant la terminologie anglo-saxonne, scanning 3D.The invention relates to the construction of non-contact synthetic images from physical three-dimensional objects. This technique is commonly called three-dimensional scanning, or, according to the English terminology, 3D scanning.
Les besoins de réaliser des images de synthèse à partir d'objets réels se font ressentir dans de nombreux secteurs de l'industrie, à commencer par les bureaux d'études où l'analyse des produits concurrents, couramment appelée ingénierie inverse ou « reverse engineering », ainsi que le partage et le stockage d'informations concernant ces produits, tendent à devenir indispensables compte tenu notamment des attentes générales en matière d'innovation et de la vitesse de renouvellement des produits. Ces secteurs ne sont pas les seuls concernés : la biométrie, la médecine (notamment la chirurgie) et l'élevage industriel (voir les documents cités ci-après) utilisent de manière croissante les techniques de numérisation tridimensionnelle. Les musées s'intéressent également à ces techniques, qui pourraient leur permettre, en réalisant à faible coût des copies d'objets anciens conservés en réserve car trop fragiles pour être exposés (notamment statues, ossements, poterie), d'augmenter de manière conséquente leur surface d'exposition.The need to create computer-generated images from real objects can be felt in many sectors of the industry, starting with consulting firms where the analysis of competing products, commonly known as reverse engineering or reverse engineering. As well as sharing and storing information about these products, they tend to become indispensable, especially given the general expectations of innovation and the speed of product renewal. These sectors are not the only ones concerned: biometrics, medicine (especially surgery) and industrial livestock farming (see documents cited below) are increasingly using 3D scanning techniques. The museums are also interested in these techniques, which could allow them, by realizing at low cost copies of old objects preserved in reserve because too fragile to be exposed (in particular statues, bones, pottery), to increase in a consequent way their exhibition surface.
Les techniques ancestrales consistaient à démonter les produits et réaliser des plans au crayon, ou à utiliser des outils de métrologie par contact. Ces méthodes, longues et fastidieuses, ont évolué au fil du temps avec l'avènement des outils de conception et de dessin assistés par ordinateur (CAO/DAO), qui permettent une conception et une représentation tridimensionnelle des objets à l'étude. Certains outils plus complets proposent un lien direct avec la fabrication (CFAO). Des solutions de prototypage rapide ont, enfin, fait récemment leur apparition en liaison avec les outils de CAO/DAO.Ancestral techniques consisted of dismantling products and making pencil drawings, or using contact metrology tools. These long and tedious methods have evolved over time with the advent of computer-aided design and drafting tools (CAD / CAD), which enable the design and three-dimensional representation of the objects under study. Some more complete tools offer a direct link to manufacturing (CFAO). Finally, rapid prototyping solutions have recently appeared in connection with CAD / CAD tools.
Il va de soi qu'un outil de numérisation tridimensionnelle, en lien avec un outil de CAO ou de CFAO, permet de réaliser un gain de temps considérable. Un tel outil comprend généralement un ou plusieurs scanneurs, portatifs ou non, réalisant une acquisition de la topographie de l'objet suivant une ou plusieurs orientations, cette topographie étant ensuite exploitée pour effectuer une reconstruction tridimensionnelle de synthèse de l'objet dans l'environnement CAO.It goes without saying that a three-dimensional scanning tool, in conjunction with a CAD or CAD / CAM tool, saves considerable time. Such a tool generally comprises one or more scanners, portable or not, performing an acquisition of the topography of the object along one or more orientations, this topography being then exploited to perform a three-dimensional synthesis reconstruction of the object in the CAD environment.
Il existe plusieurs techniques d'acquisition sans contact. Généralement ces techniques reposent sur la projection sur l'objet d'une image lumineuse ayant une forme prédéterminée (ligne, motif répétitif ou pseudo aléatoire) dont la distorsion, capturée visuellement et analysée point par point (suivant une résolution plus ou moins haute), permet de calculer, pour chaque point, des coordonnées tridimensionnelles et notamment de profondeur. Ces techniques peuvent être classées en deux grandes familles :There are several contactless acquisition techniques. Generally these techniques are based on the projection on the object of a luminous image having a predetermined shape (line, repetitive or pseudo-random pattern) whose distortion, captured visually and analyzed point by point (according to a higher or lower resolution), allows to calculate, for each point, three-dimensional coordinates and in particular depth. These techniques can be classified into two large families:
- le balayage, qui consiste à projeter sur l'objet une image linéaire (généralement un pinceau lumineux plan généré au moyen d'une source laser) et à balayer la surface de l'objet au moyen de cette ligne dont les distorsions successives permettent, au fur et à mesure, une reconstruction de la totalité de la face éclairée, etthe scanning, which consists in projecting on the object a linear image (generally a plane light brush generated by means of a laser source) and scanning the surface of the object by means of this line, the successive distortions of which allow, as and when, a reconstruction of the entire illuminated side, and
- la capture ponctuelle ou « one-shot », qui consiste à projeter sur l'objet, de manière ponctuelle, une image structurée contenant un motif prédéterminé dont la distorsion générale, par rapport à sa projection sur un plan, est analysée point par point pour permettre la reconstruction de la face éclairée.the one-shot capture, which consists in projecting onto the object, in a specific manner, a structured image containing a predetermined pattern whose general distortion, with respect to its projection on a plane, is analyzed point by point to allow the reconstruction of the illuminated side.
Ces deux techniques réalisent l'acquisition de l'image distordue au moyen d'un appareil de prise de vue ou de capture (appareil photographique ou caméra) dirigé vers la face éclairée de l'objet, cet appareil étant lui-même relié à un appareil d'analyse d'images et de reconstruction tridimensionnelle (généralement sous forme d'un module logiciel de reconstruction associé à un logiciel de CAO/DAO, implémentés sur un processeur d'ordinateur ou de calculateur).These two techniques achieve the acquisition of the distorted image by means of a camera or capture device (camera or camera) directed towards the illuminated face of the object, this apparatus being itself connected to a image analysis and three-dimensional reconstruction apparatus (generally in the form of a reconstruction software module associated with a CAD / CAD software, implemented on a computer or computer processor).
Les publications de brevets EP 0 840 880 (Crampton) et US 5 835 241 (Xerox) illustrent tous deux la technique du balayage. Cette technique a l'avantage d'être précise mais elle prend toutefois du temps (plusieurs secondes pour chaque balayage) et nécessite que l'objet soit parfaitement immobile pendant toute la durée de la projection. On comprend que cette technique soit difficilement applicable à la biométrie (sauf à des parties limitées du corps humain). En outre, l'utilisation du laser est délicate, et peut même se révéler dangereuse si l'on doit s'en servir pour scanner le visage humain. C'est pourquoi la technique du one-shot est actuellement considérée comme plus prometteuse, en raison de la rapidité, supérieure à cejle du balayage, avec laquelle l'acquisition peut être réalisée. Pour illustrer cette technique, on pourra notamment se référer aux publications de brevet US 2005/01 16952 (Je et al.), US 6 549 289 (Pheno Imaging), US 6 377 353 (Pheno Imaging), GB 2 410 794 (Sheffield Hallam University), US 2006/0120576 (Biomagnetic Imaging), US 2006/0017720 (Li), US 5 003 166 (MIT), WO 2007/105205 (Prime Sensé) et FR 2 842 591 (ENSMA/CNRS). La technique du one-shot ne va toutefois pas sans inconvénients.Patent publications EP 0 840 880 (Crampton) and US 5 835 241 (Xerox) both illustrate the scanning technique. This technique has the advantage of being precise but it takes time however (several seconds for each scan) and requires that the object be perfectly immobile for the duration of the projection. It is understood that this technique is difficult to apply to biometrics (except for limited parts of the human body). In addition, the use of the laser is delicate, and can even be dangerous if one must use it to scan the human face. This is why the one-shot technique is currently considered to be more promising because of the speed, greater than that of scanning, with which acquisition can be achieved. To illustrate this technique, reference may in particular be made to US patent publications 2005/01 16952 (Je et al.), US Pat. No. 6,549,298 (Pheno Imaging), US Pat. No. 6,377,353 (Pheno Imaging), GB 2,410,794 (Sheffield). Hallam University), US 2006/0120576 (Biomagnetic Imaging), US 2006/0017720 (Li), US 5,003,166 (MIT), WO 2007/105205 (Sense Premium) and FR 2 842 591 (ENSMA / CNRS). The one-shot technique is not without drawbacks.
L'une des difficultés majeures dont ne parviennent pas à s'affranchir la majorité des systèmes connus est le phénomène d'occultation, c'est-à- dire la présence sur la surface à numériser de zones cachées.One of the major difficulties that most of the known systems do not manage to overcome is the phenomenon of occultation, that is to say the presence on the surface to be digitized of hidden zones.
Ce phénomène se produit notamment lorsqu'un relief à la surface de l'objet à numériser projette dans son voisinage, sous l'effet de la lumière issue du projecteur, une ombre dont l'image prise par l'appareil de capture apparaît comme une tache noire et s'avère par conséquent inexploitable pour la reconstruction de la portion de surface correspondante. Le système du document FR 2 842 591 , dans lequel l'objet à numériser est éclairé en lumière incidente oblique, illustre cette problématique. Ce phénomène se produit également lorsqu'un relief présente une face cachée invisible pour l'appareil de capture. Il est à noter que la stéréovision, dans laquelle deux appareils de capture pointent simultanément vers l'objet, ne s'affranchit pas forcément des phénomènes d'occultation.This phenomenon occurs especially when a relief on the surface of the object to be scanned projects in its vicinity, under the effect of the light coming from the projector, a shadow whose image taken by the capture apparatus appears as a black spot and is therefore unusable for the reconstruction of the corresponding surface portion. The system of document FR 2 842 591, in which the object to be digitized is illuminated with oblique incident light, illustrates this problem. This phenomenon also occurs when a relief has an invisible hidden face for the capture device. It should be noted that stereovision, in which two capture devices simultaneously point towards the object, does not necessarily overcome the occultation phenomena.
On contourne en général le problème des occultations en effectuant plusieurs prises de vues successives en faisant varier l'angle d'incidence de la projection, de sorte à minimiser les zones occultées. Cependant, cette solution grève non seulement les temps de capture, en raison des prises de vues multiples pour une même surface, mais également les temps de traitement, en raison de la redondance des calculs de reconstruction pour les zones non occultées, et de la nécessité de prévoir, dans les trous correspondant aux zones occultées, des opérations de couture de portions de surface reconstruites. Ces opérations de couture sont, par nature, délicates à programmer et peuvent aboutir à des aberrations surfaciques qui compliquent la modélisation. L'invention vise notamment à remédier aux difficultés exposées ci- dessus, en proposant un système de numérisation de type one-shot, qui s'affranchisse au maximum des phénomènes d'occultation et permette une acquisition rapide et fiable des données nécessaires à la reconstruction.In general, the problem of occultations is circumvented by taking several successive shots by varying the angle of incidence of the projection, so as to minimize the hidden areas. However, this solution not only strikes the capture times, because of the multiple shots for the same surface, but also the processing times, because of the redundancy of the reconstruction calculations for the unobstructed areas, and the necessity to provide, in the holes corresponding to the occult areas, sewing operations of reconstructed surface portions. These sewing operations are inherently difficult to program and can lead to surface aberrations that complicate modeling. The invention aims in particular to remedy the difficulties described above, by proposing a one-shot scanning system, which is freed from the occultation phenomena as much as possible and allows a fast and reliable acquisition of the data necessary for the reconstruction. .
À cet effet, l'invention propose un dispositif de construction d'une image de synthèse d'une surface tridimensionnelle d'un objet physique, ce dispositif comprenant : un projecteur agencé pour projeter, suivant un axe optique de projection , une image d'un motif comprenant une multitude de points d'intensités lumineuses et/ou de couleurs prédéterminées, le projecteur étant agencé pour que l'image du motif soit nette dans un plan image prédéterminé perpendiculaire à l'axe de projection ; - une caméra axiale pointant en direction du plan image et présentant un axe optique de visée axiale, la caméra axiale étant positionnée de sorte que son axe de visée forme avec l'axe de projection un angle nul. une caméra déportée pointant en direction du plan image et présentant un axe optique de visée déportée, cette caméra étant positionnée de sorte que son axe de visée forme avec l'axe de projection un angle non nul.To this end, the invention proposes a device for constructing an image of synthesis of a three-dimensional surface of a physical object, this device comprising: a projector arranged to project, along an optical axis of projection, an image of a pattern comprising a plurality of points of light intensities and / or predetermined colors, the projector being arranged so that the image of the pattern is sharp in a predetermined image plane perpendicular to the projection axis; - An axial camera pointing in the direction of the image plane and having an axial axis of axial sight, the axial camera being positioned so that its axis of sight forms with the axis of projection a zero angle. a remote camera pointing in the direction of the image plane and having a remote optical axis of view, this camera being positioned so that its axis of sight forms with the projection axis a non-zero angle.
D'autres objets et avantages de l'invention apparaîtront à la lumière de la description faite ci-après en référence aux dessins annexés dans lesquels : - la figure 1 est une vue en perspective illustrant un dispositif de numérisation tridimensionnelle comprenant un appareil de capture relié à un ordinateur ; la figure 2 est une vue d'élévation en coupe montrant l'appareil de capture de la figure 1 ; - la figure 3 est une vue schématique de côté illustrant les principaux composants optiques de l'appareil de la figure 2, placés dans une situation de prise de vue d'un objet ; la figure 4 est une vue schématique de côté montrant les champs de vision des caméras et leurs plans objets ; - la figure 5 est une vue schématique en perspective montrant les composants représentés sur la figure 3 ; la figure 6 est une vue similaire à la figure 5, suivant un autre angle de vue ; la figure 7 est une vue en perspective montrant la surface éclairée de l'objet, située dans le champ de vision de la caméra désaxée ; la figure 8 est une vue en perspective montrant la portion de la surface éclairée de l'objet, située dans le champ de vision de la caméra axiale placée virtuellement dans l'axe de projection ; - la figure 9 est une vue en plan, dans l'axe de l'appareil de capture, du mouchetis projeté sur une face de l'objet de la figure 1.Other objects and advantages of the invention will emerge in the light of the description given hereinafter with reference to the appended drawings in which: FIG. 1 is a perspective view illustrating a three-dimensional scanning device comprising a connected capture apparatus to a computer; Fig. 2 is a sectional elevational view showing the capture apparatus of Fig. 1; FIG. 3 is a schematic side view illustrating the main optical components of the apparatus of FIG. 2, placed in a shooting situation of an object; Figure 4 is a schematic side view showing the fields of view of the cameras and their planes objects; - Figure 5 is a schematic perspective view showing the components shown in Figure 3; Figure 6 is a view similar to Figure 5, according to another angle of view; Fig. 7 is a perspective view showing the illuminated surface of the object, located in the field of view of the off-axis camera; Figure 8 is a perspective view showing the portion of the illuminated surface of the object, located in the field of view of the axial camera placed virtually in the axis of projection; FIG. 9 is a plan view, in the axis of the capture apparatus, of the speckle projected onto one face of the object of FIG.
Sur la figure 1 est représenté un dispositif 1 de numérisation sans contact, permettant de construire une image de synthèse d'une surface tridimensionnelle d'un objet physique 2. En l'occurrence on a représenté cet objet 2 sous forme d'un vase mais il pourrait s'agir de tout autre objet présentant une ou plusieurs surfaces tridimensionnelles à numériser, ces surfaces étant, en pratique, en relief, c'est-à-dire non planes. Le dispositif 1 de numérisation comprend un appareil 3 de capture optique, muni d'un boîtier 4 portatif équipé d'une poignée 5 permettant sa saisie et sa manipulation. La poignée 5 porte, sur une face avant, un déclencheur 6 manuel dont l'actionnement commande la prise de vue.FIG. 1 shows a contactless scanning device 1 for constructing an image of synthesis of a three-dimensional surface of a physical object 2. In this case, this object 2 is represented in the form of a vase but it could be any other object having one or more three-dimensional surfaces to be digitized, these surfaces being, in practice, in relief, that is to say non-planar. The scanning device 1 comprises an optical capture apparatus 3, provided with a portable casing 4 equipped with a handle 5 allowing its capture and manipulation. The handle 5 carries, on a front face, a manual release 6 whose operation commands the shooting.
Le dispositif 1 de numérisation comprend également une unité 7 de traitement des images capturées par l'appareil 3, sous forme d'un processeur sur lequel est implémentée une application logicielle de construction des images de synthèse à partir des images capturées.The scanning device 1 also comprises a unit 7 for processing the images captured by the device 3, in the form of a processor on which is implemented a software application for constructing the synthesis images from the captured images.
Le processeur peut être embarqué dans l'appareil 3 ou, comme cela est illustré sur la figure 1 , délocalisé en étant intégré dans un ordinateur 8 relié à l'appareil 3 de capture par l'intermédiaire d'une interface de communication sans fil ou filaire, par exemple sous forme d'un bus 9 informatique de type USB.The processor may be embedded in the apparatus 3 or, as illustrated in FIG. 1, relocated by being integrated in a computer 8 connected to the capture apparatus 3 via a wireless communication interface or wired, for example in the form of a computer bus 9 USB type.
L'appareil 3 de capture comprend, montés dans le boîtier 4 : un projecteur 10 lumineux ; - un dispositif 1 1 axial d'acquisition optique, de type caméraThe capture apparatus 3 comprises, mounted in the housing 4: a light projector 10; an axial optical acquisition device 1 1, of the camera type
(c'est-à-dire conçu pour réaliser des prises de vues en continu, par exemple à la cadence normalisée de 24 images par seconde), ou de type appareil photographique (c'est-à- dire réalisant des prises de vues ponctuelles), un dispositif 12 déporté d'acquisition optique, du même type que le dispositif 1 1 axial d'acquisition optique ; - un système 13 de visée optique.(ie designed for continuous shooting, for example at the normal frame rate of 24 frames per second), or camera-like type (that is to say shooting point shots), a remote optical acquisition device 12, of the same type as the axial optical acquisition device 1 1; a system 13 of optical sighting.
On suppose dans ce qui suit que les dispositifs 1 1 , 12 d'acquisition optique sont des caméras, qui, au besoin, peuvent être employées comme appareils photographiques.In the following it is assumed that the optical acquisition devices 11, 12 are cameras which, if necessary, can be used as cameras.
Le projecteur 10 comprend une source 14 lumineuse, une optique 15 de focalisation et une mire 16 interposée entre la source 14 lumineuse et l'optique 15 de focalisation.The projector 10 comprises a light source 14, a focusing optics 15 and a pattern 16 interposed between the light source 14 and the focusing optics 15.
La source 14 lumineuse est de préférence une source non cohérente de lumière blanche, notamment de type à filament ou halogène, ou encore à diode (LED). L'optique 15 de focalisation, représentée schématiquement sur les figures 3, 5 et 6 par une simple lentille convergente, définit un axe optique 17 principal passant par la source 14 lumineuse. Cet axe optique 17 définit un axe optique de projection de l'appareil 3 de capture. La mire 16 définit un mouchetis comprenant une multitude de points d'intensités lumineuses (contraste) et/ou de couleurs prédéterminées. Un tel mouchetis est représenté en plan sur la figure 9 : il s'agit ici d'un motif de type tavelures ou Speckle (pour une définition du motif de Speckle, cf. par exemple Juliette SELB, « Source virtuelle acousto-optique pour l'imagerie des milieux diffusants », Thèse de Doctorat, Paris Xl, 2002).The light source 14 is preferably a non-coherent source of white light, in particular of the filament or halogen type, or also of the diode (LED) type. The focusing optics, shown diagrammatically in FIGS. 3, 5 and 6 by a single converging lens, define a main optical axis 17 passing through the light source 14. This optical axis 17 defines an optical projection axis of the capture apparatus 3. The pattern 16 defines a speckle comprising a multitude of points of light intensities (contrast) and / or predetermined colors. Such speckling is shown in plan in Figure 9: this is a scab-type pattern or Speckle (for a definition of the Speckle pattern, see for example Juliette SELB, "Acousto-optical virtual source for imaging of diffusing media, PhD thesis, Paris Xl, 2002).
En pratique, la mire 16 se présente sous la forme d'une plaque translucide ou transparente (en verre ou en matière plastique), carrée ou rectangulaire, de type diapositive, sur laquelle le mouchetis est imprimé par un procédé classique (transfert, offset, sérigraphie, flexographie, laser, jet d'encre, microlithographie, etc.).In practice, the target 16 is in the form of a translucent or transparent plate (glass or plastic), square or rectangular, of the slide type, on which the speckle is printed by a conventional method (transfer, offset, screen printing, flexography, laser, inkjet, microlithography, etc.).
La mire 16 est disposée entre la source 14 lumineuse et l'optique 15, sur l'axe 17 de projection, c'est-à-dire perpendiculairement à l'axe 17 de projection et de sorte que celui-ci passe par le centre de la mire 16 (défini en l'occurrence par la croisée de ses diagonales). La mire 16 est placée à une distance prédéterminée de l'optique 15 dont elle constitue un plan objet, de telle sorte que l'image du motif soit nette dans un plan image prédéterminé perpendiculaire à l'axe 17 de projection. L'exemple donné ci-après fournit des valeurs numériques préférées.The pattern 16 is disposed between the light source 14 and the optic 15, on the axis 17 of projection, that is to say perpendicularly to the projection axis 17 and so that it passes through the center of the target 16 (defined in this case by the crossing of its diagonals). The target 16 is placed at a predetermined distance from the optics 15 of which it constitutes an object plane, so that the image of the pattern is clear. in a predetermined image plane perpendicular to the projection axis 17. The example given below provides preferred numerical values.
La caméra 1 1 axiale comprend une optique 18 de focalisation, représentée schématiquement sur les figures 3, 5 et 6 par une simple lentille convergente, et définissant un axe optique 19 de visée axiale.The camera 1 1 axial comprises a focusing optics 18, shown schematically in Figures 3, 5 and 6 by a single converging lens, and defining an optical axis 19 axial sight.
La caméra 1 1 axiale comprend en outre un capteur 20 photosensible, par exemple de type CCD, qui se présente sous forme d'une plaque carrée ou rectangulaire placée, en regard de l'optique 18 de focalisation, sur l'axe optique 19 de visée axiale, c'est-à-dire perpendiculairement à celui-ci et de sorte que l'axe 19 passe par le centre du capteur 20 (défini en l'occurrence par la croisée de ses diagonales).The camera 1 1 axial further comprises a photosensitive sensor 20, for example CCD type, which is in the form of a square or rectangular plate placed, facing the optics 18 of focus, on the optical axis 19 of axial view, that is to say perpendicular to it and so that the axis 19 passes through the center of the sensor 20 (defined in this case by the crossing of its diagonals).
La caméra 1 1 axiale est orientée de sorte à pointer en direction du plan image du projecteur 10, en étant positionnée de sorte que son axe 19 de visée forme avec l'axe 17 de projection un angle virtuellement nul.The camera 1 1 axial is oriented so as to point in the direction of the image plane of the projector 10, being positioned so that its axis of sight 19 forms with the axis 17 projection a virtually zero angle.
Plus précisément, la caméra 1 1 axiale est positionnée de sorte que son axe 19 de visée soit perpendiculaire à l'axe 17 de projection et concourant avec celui-ci, tout en étant situé dans un plan médian de la mire 16. Dans ce qui- suit, on nomme plan de visée le plan contenant l'axe 17 de projection et l'axe 19 de visée axiale.More specifically, the camera 1 1 axial is positioned so that its axis 19 of sight is perpendicular to the axis 17 of projection and concurrent with it, while being located in a median plane of the target 16. In what Next, the plan containing the projection axis 17 and the axis 19 of axial aiming is called the aiming plane.
Un séparateur 21 optique est disposé sur l'axe 17 de projection à son intersection avec l'axe optique 19 de visée axiale. Ce séparateur 21 optique peut se présenter sous forme d'une lame mince ou épaisse, ou encore sous forme d'un prisme.An optical splitter 21 is disposed on the projection axis 17 at its intersection with the optical axis 19 of axial aiming. This optical separator 21 can be in the form of a thin or thick blade, or in the form of a prism.
En l'occurrence, le séparateur 21 optique se présente sous forme d'une lame 21 inclinée de 45° par rapport à l'axe 17 de projection (et donc également par rapport à l'axe 19 de visée de la caméra axiale). Elle présente deux faces principales planes opposées, à savoir une face 22 arrière, tournée du côté du projecteur 10, et une face 23 avant, tournée du côté de la caméra 1 1 axiale.In this case, the optical separator 21 is in the form of a blade 21 inclined by 45 ° with respect to the axis 17 of projection (and therefore also with respect to the axis 19 of sight of the axial camera). It has two opposite planar main faces, namely a rear face 22, turned on the side of the projector 10, and a front face 23, turned towards the camera 1 1 axial.
La face 22 arrière est prévue pour transmettre suivant l'axe 17 de projection la lumière incidente en provenance du projecteur 10. La face avant 23 est semi-réfléchissante, c'est-à-dire qu'elle est prévue pour transmettre suivant l'axe 17 de projection la lumière incidente en provenance du projecteur 10, mais pour réfléchir, suivant l'axe 19 de visée axiale et vers la caméra 1 1 axiale, la lumière réfléchie qui lui parvient, suivant l'axe 17 de projection, de l'objet 2 éclairé.The rear face 22 is designed to transmit along the axis 17 of projection the incident light from the projector 10. The front face 23 is semi-reflective, that is to say that it is intended to transmit according to the projection axis 17 incident light from the projector 10, but to reflect, along the axis 19 of axial view and to the camera 1 1 axial, the reflected light that reaches him, along the axis 17 of projection, the object 2 illuminated.
La lame 21 séparatrice est disposée de telle sorte que l'axe 17 de projection et l'axe 19 de visée axiale soient concourants sur la face 23 avant semi-réfléchissante, et plus précisément au centre de celle-ci, défini par la croisée de ses diagonales.The separating blade 21 is arranged in such a way that the projection axis 17 and the axial viewing axis 19 are concurrent on the semi-reflecting front face 23, and more precisely in the center thereof, defined by the cross-section of its diagonals.
De la sorte, la caméra 1 1 axiale forme une caméra virtuelle située sur l'axe 17 de projection.In this way, the camera 1 1 axial forms a virtual camera located on the axis 17 of projection.
Le capteur 20 est placé à une distance prédéterminée de l'optique 18, dans un plan image situé à une distance prédéterminée de celle-ci, dépendant de sa focale (voir l'exemple ci-dessous) et telle que le plan objet 24 correspondant à ce plan image soit sensiblement confondu avec le plan image du projecteur 10.The sensor 20 is placed at a predetermined distance from the optics 18, in an image plane situated at a predetermined distance from it, depending on its focal length (see the example below) and such that the corresponding object plane 24 at this image plane is substantially coincident with the image plane of the projector 10.
Dans un mode de réalisation préféré, cette caméra virtuelle est située devant le projecteur 10 plutôt qu'en arrière de celui-ci, c'est-à- dire que la longueur du chemin optique séparant le plan objet 24 de la caméra 1 1 axiale (c'est-à-dire le plan image du projecteur 10) et le plan image de celle-ci (dans lequel s'étend le capteur 20) est inférieure à la longueur du chemin optique séparant le plan objet du projecteur 10 (dans lequel s'étend la mire 16) et le plan image de celui-ci. Concrètement, compte tenu de la présence de la lame 21 séparatrice, cette disposition se traduit par le fait que la distance de la caméra 11 axiale à la lame 21 séparatrice est inférieure à la distance du projecteur 10 à la lame 21 séparatrice. Cela permet d'utiliser un capteur 20 de taille raisonnable (et donc de coût raisonnable), dont le champ de vision soit strictement inclus dans l'image du mouchetis.In a preferred embodiment, this virtual camera is located in front of the projector 10 rather than behind it, that is to say that the length of the optical path separating the object plane 24 from the camera 1 1 axial (i.e. the image plane of the projector 10) and the image plane thereof (in which the sensor 20 extends) is less than the length of the optical path separating the object plane from the projector 10 (in which extends the target 16) and the image plane thereof. Specifically, given the presence of the separator blade 21, this arrangement results in the fact that the distance from the axial camera 11 to the separator blade 21 is less than the distance of the projector 10 to the separating blade 21. This makes it possible to use a sensor 20 of reasonable size (and therefore of reasonable cost), the field of view of which is strictly included in the image of the speckle.
La caméra 12 déportée est équipée d'une optique 25 de focalisation, représentée schématiquement sur les figures 3, 5 et 6 par une simple lentille convergente, et définissant un axe optique 26 de visée déportée.The remote camera 12 is equipped with a focusing optics 25, shown diagrammatically in FIGS. 3, 5 and 6 by a single convergent lens, and defining an optical axis 26 for remote viewing.
La caméra 12 déportée comprend en outre un capteur 27 photosensible, par exemple de type CCD, qui se présente sous forme d'une plaque carrée ou rectangulaire placée, en regard de l'optique 25 de focalisation, sur l'axe optique 26 de visée déportée, c'est-à-dire perpendiculairement à celui-ci et de sorte que l'axe 26 passe par le centre du capteur 27 (défini en l'occurrence par la croisée de ses diagonales).The remote camera 12 furthermore comprises a photosensitive sensor 27, for example of the CCD type, which is in the form of a square or rectangular plate placed, facing the focusing optics 25, on the optical axis 26 of aiming. deported, that is to say perpendicular to it and so that the axis 26 passes through the center of the sensor 27 (defined in this case by the crossing of its diagonals).
La caméra 12 déportée est orientée de sorte à pointer en direction du plan image du projecteur 10, en étant positionnée de sorte que son axe 26 de visée forme avec l'axe 17 de projection un angle α non nul (voir l'exemple numérique ci-après) et soit situé dans le plan de visée (en d'autres termes, l'axe 17 de projection, l'axe 19 de visée axiale et l'axe 26 de visée déportée sont coplanaires).The remote camera 12 is oriented so as to point in the direction of the image plane of the projector 10, being positioned so that its viewing axis 26 forms with the projection axis 17 a non-zero angle α (see the numerical example of FIG. -after) and is located in the plane of sight (in other words, the projection axis 17, the axial viewing axis 19 and the remote viewing axis 26 are coplanar).
Le capteur 27 est placé à une distance prédéterminée de l'optique 25, dans un plan image situé à une distance prédéterminée de celle-ci, dépendant de sa focale (voir l'exemple ci-dessous) et telle que : le centre du plan objet 28 correspondant à ce plan image soit situé sur l'axe 17 de projection ;The sensor 27 is placed at a predetermined distance from the optic 25, in an image plane situated at a predetermined distance from it, depending on its focal length (see the example below) and such that: the center of the plane object 28 corresponding to this image plane is located on the axis 17 projection;
- le plan objet 24 de la caméra 1 1 axiale soit inclus dans le champ de vision du capteur 27 de la caméra 12 déportée.- The object plane 24 of the camera 1 1 axial is included in the field of view of the sensor 27 of the camera 12 remote.
Cette configuration, illustrée sur la figure 4, qui impose un décalage du plan objet 28 de la caméra 12 déportée par rapport au plan objet 24 de la caméra 1 1 axiale, parallèlement à l'axe 17 de projection, constitue le meilleur compromis entre une bonne netteté et un recouvrement maximal des champs de vision des deux capteurs 20, 27.This configuration, illustrated in FIG. 4, which imposes a shift of the object plane 28 of the camera 12 offset with respect to the object plane 24 of the axial camera 1 1, parallel to the projection axis 17, constitutes the best compromise between a good sharpness and maximum coverage of the fields of view of the two sensors 20, 27.
En outre, la caméra 12 déportée est positionnée de telle sorte que la longueur du chemin optique séparant le plan objet 28 de la caméra 12 déportée (dont l'intersection avec le plan image du projecteur 10 est une droite perpendiculaire au plan de visée et passant par le centre du plan image du projecteur 10) et le plan image de celle-ci (dans lequel s'étend le capteur 27) est inférieure à la longueur du chemin optique séparant le plan objet du projecteur 10 (dans lequel s'étend la mire 16) et le plan image de celui-ci. Comme dans le cas de la caméra 11 axiale, cette disposition permet d'utiliser un capteur 27 de taille raisonnable (et donc de coût raisonnable), dont le champ de vision soit strictement inclus dans l'image du mouchetis.In addition, the remote camera 12 is positioned in such a way that the length of the optical path separating the object plane 28 from the remote camera 12 (whose intersection with the image plane of the projector 10 is a line perpendicular to the viewing plane and passing through by the center of the image plane of the projector 10) and the image plane thereof (in which the sensor 27 extends) is less than the length of the optical path separating the object plane from the projector 10 (in which the 16) and the image plane of it. As in the case of the camera 11 axial, this arrangement allows to use a sensor 27 of reasonable size (and therefore reasonable cost), whose field of view is strictly included in the image of speckling.
Le système 13 de visée est agencé pour permettre, préalablement à la prise de vue, un positionnement de l'appareil 3 à une distance de l'objet 2 telle que la projection sur celui-ci du mouchetis (c'est-à-dire de l'image de la mire 16) soit aussi nette que possible.The sighting system 13 is arranged to allow, prior to the shooting, a positioning of the apparatus 3 at a distance from the object 2 such that the projection thereon of the speckle (i.e. 16) be as clean as possible.
Ce système 13 de visée comprend deux pointeurs 29, 30 laser montés dans le boîtier 4 de l'appareil, conçus pour émettre chacun, lorsque le déclencheur 6 est enfoncé, un rayon ou faisceau lumineux 31 , 32 linéaire produisant, sur toute surface éclairée, une tache lumineuse 33 sensiblement ponctuelle.This sighting system 13 comprises two laser pointers 29, mounted in the housing 4 of the apparatus, designed to emit each, when the trigger 6 is depressed, a ray or linear light beam 31, 32 producing, on any illuminated surface, a light spot 33 substantially punctual.
Les pointeurs 29, 30 sont positionnés angulairement dans le boîtier 4 pour que les rayons 31 , 32 émis se croisent en un point d'intersection situé sur l'axe 17 de projection, sensiblement dans le plan image du projecteur 10.The pointers 29, 30 are angularly positioned in the casing 4 so that the radii 31, 32 emitted intersect at a point of intersection located on the projection axis 17, substantially in the image plane of the projector 10.
On fournit ci-après un exemple expérimental de dimensionnement et de positionnement du projecteur 10 et des caméras 1 1 , 12 :An experimental example of dimensioning and positioning of the projector 10 and the cameras 11, 12 is given below:
Projecteur 10 :Projector 10:
Figure imgf000012_0001
Figure imgf000012_0001
Caméra 1 1 axiale :1 1 axial camera:
Figure imgf000012_0002
Figure imgf000012_0002
Caméra 12 déportée :12 deported camera:
Figure imgf000012_0003
Figure imgf000012_0003
Le dimensionnement préféré (cf. colonne « valeur préférée »), permet de projeter dans le plan image du projecteur 10, situé à 481 mm de l'optique 15 de celui-ci (cette valeur peut aisément être déduite des valeurs fournies par la relation de conjugaison des lentilles minces) une image nette du mouchetis (figure 9), dont le grand côté mesure 260 mm environ, cette image étant strictement incluse dans les champs des capteurs 20, 27. En fonctionnement, l'appareil 3 de capture est positionné face à l'objet 2, en regard d'une surface de celui-ci que l'on souhaite numériser. Le déclencheur 6 est alors enfoncé, ce qui provoque l'allumage des pointeurs 29, 30 lasers et l'émission de leurs faisceaux 31 , 32 respectifs.The preferred dimensioning (see column "preferred value"), makes it possible to project in the image plane of the projector 10, located at 481 mm from the optical 15 thereof (this value can easily be deduced from the values provided by the relationship of thin lens conjugation) a sharp image of the speckled (Figure 9), whose large side measures approximately 260 mm, this image being strictly included in the fields of the sensors 20, 27. In operation, the capture apparatus 3 is positioned facing the object 2, facing a surface thereof that it is desired to digitize. The trigger 6 is then depressed, which causes the ignition of the pointers 29, 30 lasers and the emission of their respective beams 31, 32.
Tout en maintenant enfoncé le déclencheur 6, la distance de l'appareil 3 à l'objet 2 est alors ajustée de sorte que l'intersection des faisceaux 31 , 32 laser soit située à la surface de l'objet 2, c'est-à-dire de sorte qu'une seule tache 33 lumineuse apparaisse à la surface de l'objet 2. Le point de la surface de l'objet correspondant à la tache 33 se trouve alors sensiblement dans le plan image du projecteur 10, ce qui permet de minimiser le flou dont sera affectée l'image du mouchetis projetée sur l'objet 2.While pressing the trigger 6, the distance from the apparatus 3 to the object 2 is then adjusted so that the intersection of the beams 31, 32 laser is located on the surface of the object 2, that is, that is, so that only one light spot 33 appears on the surface of the object 2. The point of the surface of the object corresponding to the spot 33 is then substantially in the image plane of the projector 10, which minimizes the blur that will affect the image of speckled projected on object 2.
Le relâchement du déclencheur 6 provoque l'allumage de la source 14 lumineuse et la projection du mouchetis sur l'objet 2.The release of the trigger 6 causes the ignition of the light source 14 and the projection of speckled on the object 2.
Le mécanisme de déclenchement peut être du type flash, c'est-à- dire que la projection du mouchetis et la prise de vue sont réalisées ponctuellement et simultanément, ou bien de type retardé, c'est-à-dire que la prise de vue peut être déclenchée - de manière automatique ou manuelle - pendant un intervalle de temps au cours duquel la projection est effectuée en continu. On peut également prévoir un fonctionnement en rafale, dans lequel plusieurs prises de vues sont effectuées successivement à intervalles de temps prédéterminés.The triggering mechanism may be of the flash type, that is to say that the projection of speckling and shooting are performed punctually and simultaneously, or of delayed type, that is to say that the taking of The view can be triggered - automatically or manually - for a period of time during which the projection is done continuously. Burst operation can also be provided in which several shots are taken successively at predetermined time intervals.
La lumière blanche incidente émise par la source 14 lumineuse traverse en premier lieu la mire 16, est focalisée par l'optique 15 puis traverse sans réflexion la lame 21 séparatrice. Cette lumière éclaire - avec projection de la mire 16 - l'objet à numériser.The incident white light emitted by the light source 14 first passes through the target 16, is focused by the optics 15 and then passes without reflection the separating plate 21. This light illuminates - with projection of the target 16 - the object to be digitized.
La portion de la surface éclairée de l'objet 2 située dans le champ de vision de la caméra 1 1 axiale, représentée sur la figure 7, émet une lumière réfléchie suivant l'axe 19 de visée axiale, en sens inverse de la lumière incidente. Cette lumière réfléchie subit une seconde réflexion à angle droit sur la face avant 23 de la lame 21 séparatrice en direction de la caméra 1 1 . La lumière ainsi deux fois réfléchie est focalisée par l'optique 18 de la caméra 1 1 axiale et vient frapper le capteur 20, qui acquiert ainsi une première image déformée du mouchetis projeté sur l'objet 2. Grâce à la disposition particulière, décrite ci-dessus, de la caméra 1 1 axiale, l'axe 19 de visée axiale est virtuellement confondu avec l'axe 17 de projection. Autrement dit, bien que la caméra 1 1 axiale ne soit pas disposée physiquement sur l'axe 17 de projection, elle se trouve dans cet axe 17 dans la mesure où tout se passe comme si la lumière réfléchie par l'objet 2 et frappant le capteur 20 n'avait subi aucune déviation.The portion of the illuminated surface of the object 2 located in the field of view of the camera 1 1 axial, shown in Figure 7, emits light reflected along the axis 19 of axial sight, in the opposite direction of the incident light . This reflected light undergoes a second reflection at right angles to the front face 23 of the splitter plate 21 towards the camera January 1. The twice reflected light is focused by the optics 18 of the camera 1 1 axial and hits the sensor 20, which acquires a first deformed image of the speckled projected on the object 2. Thanks to the particular arrangement, described above, of the camera 1 1 axial axis 19 axial sight is virtually coincident with the axis 17 projection. In other words, although the camera 1 1 axial is not physically disposed on the axis 17 of projection, it is in this axis 17 to the extent that everything happens as if the light reflected by the object 2 and striking the sensor 20 had not undergone any deviation.
L'interposition de la lame 21 séparatrice permet, en pratique, d'éviter l'occultation du projecteur 10 que provoquerait le montage physique de la caméra 1 1 axiale sur l'axe 17 de projection devant le projecteur 10.The interposition of the splitter blade 21 makes it possible, in practice, to avoid the concealment of the projector 10 that would be caused by the physical assembly of the camera 1 1 axial on the axis 17 of projection in front of the projector 10.
La portion de la surface éclairée de l'objet 2 située dans le champ de vision de la caméra 12 déportée, représentée sur la figure 8, émet une lumière réfléchie suivant l'axe 26 de visée déportée. Cette lumière est focalisée par l'optique 25 de la caméra déportée et vient frapper le capteur 27, qui acquiert ainsi une seconde image déformée du mouchetis projeté sur l'objet 2, simultanément à l'acquisition par le capteur 20 de la première image.The portion of the illuminated surface of the object 2 located in the field of view of the remote camera 12, shown in FIG. 8, emits light reflected along the remote viewing axis 26. This light is focused by the optics 25 of the remote camera and hits the sensor 27, which thus acquires a second deformed image of the speckled projected on the object 2, simultaneously with the acquisition by the sensor 20 of the first image.
Les images ainsi capturées sont transférées vers l'unité 7 de traitement, qui opère la reconstruction tridimensionnelle de la surface éclairée de l'objet 2 sur la triple base de ces deux images déformées du mouchetis, et de l'image non déformée du mouchetis telle que projetée sur un plan confondu avec le plan image du projecteur 10.The images thus captured are transferred to the processing unit 7, which operates the three-dimensional reconstruction of the illuminated surface of the object 2 on the triple base of these two deformed images of the speckle, and the undistorted image of the speckle such as that projected on a plane confused with the image plane of the projector 10.
Dans un premier temps, l'unité 7 de traitement effectue une mise en correspondance de l'image du mouchetis déformé issue de la caméra 12 déportée avec l'image du mouchetis déformé issu de la caméra 1 1 axiale. Cette mise en correspondance peut être effectuée pour chaque point du mouchetis, ou en une sélection de points prédéterminés, effectuée au sein de l'image non déformée. Afin d'obtenir une construction aussi précise que possible, il est préférable que la mise en correspondance soit faite pour chaque point de l'image, c'est-à-dire, concrètement, pour chaque pixel de l'image acquise par le capteur de la caméra 12 déportée. Il va de soi que la précision de la construction dépend de la précision du capteur 27. Le dimensionnement préféré proposé ci-dessus fournit, pour un capteur 27 comprenant de l'ordre de 1 million de pixels, une précision de l'ordre du dixième de mm, suffisante pour construire une image de synthèse acceptable de tout type d'objet dont la taille est à échelle humaine.In a first step, the processing unit 7 performs a mapping of the image of the deformed speckle from the remote camera 12 with the image of the deformed speckle from the axial camera 11. This mapping can be performed for each point of the speckle, or in a selection of predetermined points, performed within the undistorted image. In order to obtain as precise a construction as possible, it is preferable that the mapping be done for each point of the image, that is to say, concretely, for each pixel of the image acquired by the sensor. of the deported camera. It goes without saying that the accuracy of the construction depends on the accuracy of the sensor 27. The preferred dimensioning proposed above provides, for a sensor 27 comprising of the order of 1 million pixels, a precision of the order of one tenth of mm, sufficient to build an image of acceptable synthesis of any type of object whose size is on a human scale.
L'unité 7 de traitement effectue, à partir de cette mise en correspondance, une première reconstruction de la surface à numériser au moyen d'un calcul de triangulation, de sorte à obtenir un nuage de points.The processing unit 7 performs, from this mapping, a first reconstruction of the surface to be digitized by means of a triangulation calculation, so as to obtain a cloud of points.
L'opération suivante consiste à compléter et affiner le nuage de points ainsi construit en appariant, pour l'ensemble des points du nuage ou pour une sélection de points, chaque point du mouchetis non déformé avec le point correspondant du mouchetis déformé.The next step consists in completing and refining the cloud of points thus constructed by matching, for all the points of the cloud or for a selection of points, each point of the undistorted speckle with the corresponding point of the deformed speckle.
Pour chaque point, cet appariement peut être réalisé par corrélation, c'est-à-dire par approches successives au sein de zones qui, bien que présentant des disparités locales, apparaissent ressemblantes dans des régions voisines des deux images. Une fois chaque point apparié, l'unité 7 de traitement mesure pour ce point la déviation subie, c'est-à-dire, le décalage dans l'image du mouchetis déformé de la position du point par rapport à sa position dans l'image du mouchetis non déformé.For each point, this pairing can be achieved by correlation, that is to say by successive approaches within zones which, although having local disparities, appear similar in neighboring regions of the two images. Once each paired point, the processing unit 7 measures for this point the deviation undergone, that is to say, the shift in the image of the deformed speckle of the position of the point relative to its position in the image of undistorted speckle.
Chacune de ces images étant plane, l'unité de traitement décompose cette déviation en une composante horizontale (parallèlement à l'axe des abscisses) et une composante verticale (parallèlement à l'axe des ordonnées).Each of these images being flat, the processing unit decomposes this deviation into a horizontal component (parallel to the abscissa axis) and a vertical component (parallel to the ordinate axis).
L'unité 7 de traitement en déduit ensuite, par un calcul de triangulation effectué au sein de l'unité de traitement à partir des données issues du capteur, au moins la coordonnée de profondeur du point de l'image du mouchetis déformé correspondant au point sélectionné dans l'image du mouchetis non déformé.The processing unit 7 derives thereafter, by a calculation of triangulation carried out within the processing unit from the data coming from the sensor, at least the depth coordinate of the point of the image of the deformed speckle corresponding to the point selected in the image of undistorted mouchetis.
Compte tenu de l'inclinaison de l'axe 26 de visée déportée par rapport à l'axe 17 de projection, des occultations peuvent se produire dans l'image déformée, en raison notamment de reliefs à la surface de l'objet 2.Given the inclination of the remote viewing axis 26 relative to the projection axis 17, occultations can occur in the deformed image, in particular due to reliefs on the surface of the object 2.
L'unité 7 de traitement répète les opérations de comparaison, d'appariement (c'est-à-dire de corrélation), de mesure de la déviation des points sélectionnés et de calcul de la coordonnée de profondeur de chaque point pour l'image déformée du mouchetis telle que capturée et transmise par la caméra 1 1 axiale. Certains des points, déjà calculés à partir de l'image déformée issue de la caméra 12 déportée, sont ainsi recalculés et sont par conséquent redondants. Cette redondance est utilisée par l'unité 7 de traitement pour affiner la position tridimensionnelle de ces points à partir de la double mesure.The processing unit 7 repeats the operations of comparison, of pairing (that is to say of correlation), of measuring the deviation of the selected points and of calculating the depth coordinate of each point for the image. deformed mouchetis as captured and transmitted by the camera 1 1 axial. Some of the points, already calculated from the deformed image from the remote camera 12, are thus recalculated and are therefore redundant. This redundancy is used by the processing unit 7 to refine the three-dimensional position of these points from the double measurement.
Certains des points calculés à partir de l'image déformée issue de la caméra 1 1 axiale, cependant, peuvent correspondre à des zones occultées dans l'image déformée issue de la caméra 12 déportée.Some of the points calculated from the distorted image from the axial camera 1 1, however, may correspond to obscured areas in the deformed image from the remote camera 12.
Ces points, non redondants, sont utilisés par l'unité 7 de traitement pour compléter les zones occultées. In fine, l'unité de traitement reconstruit ainsi une image de synthèse dense de la surface éclairée de l'objet 2, au moins dans la partie située à l'intersection des champs de vision des deux caméras 1 1 , 12.These non-redundant points are used by the processing unit 7 to complete the obscured areas. Ultimately, the processing unit reconstructs a dense synthetic image of the illuminated surface of the object 2, at least in the portion at the intersection of the fields of view of the two cameras 1 1, 12.
La configuration de l'appareil permet d'éviter les phénomènes d'occultation. Il n'est donc pas nécessaire d'effectuer plusieurs prises de vue d'une même surface pour en obtenir une reconstruction complète de celle-ci, au bénéfice de la simplicité et de la rapidité d'exécution.The configuration of the device makes it possible to avoid occultation phenomena. It is therefore not necessary to take several shots of the same surface to obtain a complete reconstruction thereof, for the benefit of simplicity and speed of execution.
En outre, les deux caméras se complètent mutuellement : la caméra 1 1 axiale permet non seulement d'affiner les mesures issues de la caméra 12 déportée, mais aussi de compléter les zones éventuellement occultées, tandis que la caméra 12 déportée permet d'obtenir une reconstruction de la surface au voisinage de l'axe de projection, où la faiblesse de l'angle solide du champ de vision de la caméra 1 1 axiale ne permet pas d'obtenir une précision suffisante des mesures.In addition, the two cameras complement each other: the camera 1 1 axial allows not only to refine the measurements from the remote camera 12, but also to complete the areas possibly obscured, while the camera 12 remote allows to obtain a reconstruction of the surface in the vicinity of the projection axis, where the weakness of the solid angle of the field of view of the camera 1 1 axial does not provide sufficient accuracy of the measurements.
Les opérations de prise de vue pourront être répétées à volonté sur différentes faces de l'objet, de sorte à obtenir une reconstruction complète de celui-ci. Des opérations classiques de couture seront prévues pour joindre les différentes surfaces reconstruites. The shooting operations can be repeated at will on different sides of the object, so as to obtain a complete reconstruction thereof. Classic sewing operations will be planned to join the different reconstructed surfaces.

Claims

REVENDICATIONS
1. Dispositif (1 ) de construction d'une image de synthèse d'une surface tridimensionnelle d'un objet (2) physique, ce dispositif comprenant : un projecteur (10) agencé pour projeter, suivant un axe optique (17) de projection, une image d'un motif comprenant une multitude de points d'intensités lumineuses et/ou de couleurs prédéterminées, le projecteur (10) étant agencé pour que l'image du motif soit nette dans un plan image prédéterminé perpendiculaire à l'axe (17) de projection ; une caméra (1 1 ) axiale pointant en direction du plan image et présentant un axe optique (19) de visée axiale, la caméra (1 1 ) axiale étant positionnée de sorte que son axe (19) de visée forme avec l'axe de projection un angle (α) nul ; une caméra (12) déportée pointant en direction du plan image et présentant un axe optique (26) de visée déportée, cette caméra1. Device (1) for constructing an image of synthesis of a three-dimensional surface of a physical object (2), this device comprising: a projector (10) arranged to project, along an optical axis (17) of projection , an image of a pattern comprising a plurality of points of light intensities and / or predetermined colors, the projector (10) being arranged so that the image of the pattern is sharp in a predetermined image plane perpendicular to the axis ( 17) projection; an axial camera (1 1) pointing in the direction of the image plane and having an axial axis (19) of axial viewing, the camera (1 1) being positioned axially so that its axis (19) of sight forms with the axis of projection a zero angle (α); a remote camera (12) pointing in the direction of the image plane and having an optical axis (26) for remote viewing, this camera
(12) étant positionnée de sorte que son (26) axe de visée forme avec l'axe (17) de projection un angle non nul, et de telle sorte que - le centre d'un plan objet (28) de la caméra (12) déportée soit situé sur l'axe (17) de projection ; un plan objet (24) de la caméra (11 ) axiale soit inclus dans le champ de vision de la caméra (12) déportée.(12) being positioned so that its (26) sighting axis forms a non-zero angle with the projection axis (17), and so that - the center of an object plane (28) of the camera ( 12) offset is located on the axis (17) of projection; an object plane (24) of the axial camera (11) is included in the field of view of the remote camera (12).
2. Dispositif (1 ) selon la revendication 1 , dans lequel la caméra (12) déportée est positionnée de sorte que l'intersection de son axe2. Device (1) according to claim 1, wherein the camera (12) offset is positioned so that the intersection of its axis
(26) de visée et de l'axe de projection soit située sensiblement dans le plan image.(26) and the projection axis is located substantially in the image plane.
3. Dispositif (1 ) selon la revendication 2, dans lequel la caméra (12) .déportée comprend une optique (25) de focalisation définissant l'axe (26) de visée de la caméra (12), et un capteur (27) optique positionné sensiblement dans un plan image de l'optique (25) de visée correspondant à un plan objet contenant le point de l'axe de projection situé dans le plan image du projecteur (10).3. Device (1) according to claim 2, wherein the camera (12) .deportée comprises an optics (25) focusing defining the axis (26) of sight of the camera (12), and a sensor (27) optical lens positioned substantially in an image plane of the viewing optics (25) corresponding to an object plane containing the point of the projection axis located in the image plane of the projector (10).
4. Dispositif (1 ) selon l'une des revendications 1 à 3, dans lequel la caméra (11 ) axiale comprend une optique (18) de focalisation définissant l'axe (17) de visée de la caméra (1 1 ), et un capteur (20) optique positionné sensiblement dans un plan image de l'optique (12) de focalisation correspondant à un plan objet sensiblement confondu avec le plan image du projecteur (10).4. Device (1) according to one of claims 1 to 3, wherein the camera (11) comprises a focusing optics (18) defining the axis (17) of sight of the camera (1 1), and an optical sensor (20) positioned substantially in an image plane of the optics (12) focusing device corresponding to an object plane substantially coincident with the image plane of the projector (10).
5. Dispositif (1 ) selon l'une des revendications 1 à 4, qui comprend une lame (21 ) séparatrice placée sur l'axe (17) de projection, et en regard de laquelle est positionnée la caméra (1 1 ) axiale.5. Device (1) according to one of claims 1 to 4, which comprises a blade (21) separator placed on the axis (17) of projection, and opposite which is positioned the camera (1 1) axial.
6. Dispositif (1 ) selon la revendication 5, dans lequel la distance de la caméra (11 ) axiale à la lame (21 ) séparatrice est inférieure à la distance du projecteur (10) à la lame (21 ) séparatrice.6. Device (1) according to claim 5, wherein the distance from the camera (11) to the axial blade (21) separator is less than the distance of the projector (10) to the blade (21) separator.
7. Dispositif (1 ) selon l'une des revendications 1 à 6, qui comprend deux pointeurs (29, 30) agencés pour émettre deux rayons lumineux se croisant en un point (33) d'intersection situé sur l'axe (17) de projection.7. Device (1) according to one of claims 1 to 6, which comprises two pointers (29, 30) arranged to emit two light rays intersecting at a point (33) of intersection located on the axis (17) projection.
8. Dispositif (1 ) selon la revendication 7, dans lequel les pointeurs (29, 30) sont positionnés pour que le point (33) d'intersection des rayons des pointeurs (29, 30) se trouve sensiblement dans le plan image du projecteur (10).8. Device (1) according to claim 7, wherein the pointers (29, 30) are positioned so that the point (33) of intersection of the spokes of the pointers (29, 30) is substantially in the image plane of the projector (10).
9. Dispositif (1 ) selon la revendication 7 ou 8, dans lequel les pointeurs (29, 30) sont des lasers. 9. Device (1) according to claim 7 or 8, wherein the pointers (29, 30) are lasers.
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