Omnidirectional scanner

0001The invention relates to a method for three-dimensional Detection of an object. the invention provides a further relates Device for carrying out the method and a use of the apparatus and method.

0002A method for three-dimensional detection and digitization objects are used for different purposes, for example in the development, production and quality control Industrial products and components. In the Medical used, for example, optical methods for the production of housing in the ear hearing aids portable. For individual adaptation to the auditory canal of a housing a hearing aid will be supported by an audiologist by means of a rubber-like plastic mass footprints from external auditory canal of the patient created. In order for the production the housing stereo-lithographic or similar processes To apply, have three-dimensional of the ear marks Computer models are created. This process is carried out so far on the hearing aid manufacturers. There, the footprints are completely measured in three dimensions with a precision scanner and on the basis of this data, a 3D computer model of the external auditory meatus created. Subsequently, in a Laser sintering process the production of individually formed Shell based on the data of the computer model.

0003The precision scanner used mostly as a laser scanner formed, in which controls a laser beam is guided over the surface of the impression and the backscattered Light by a detector (for example a CCD camera) of is observed a different from the laser beam direction. The surface coordinates of the impression then by triangulation calculated. In the known laser scanner VIVID 910 Fa. Minolta is out of the laser beam, a line generated which, on the surface of the object to be detected eg an ear impression, is moved. The image of the line is again observed with a camera, from the deformation the line image by triangulation on the surface coordinates be the object to be detected closed can. As an accessory to the known laser scanner used Turntable (Rotary Stage Controller), on which the object rotates during scanning by 360 °.

0004A disadvantage of the known laser scanners are their high Cost, sometimes even by the high-precision Mechanics of the turntable caused.

0005From Frank Forster, Manfred Lang, Bernd Radig "Real-Time Range Imaging for Dynamic Scenes Using Colour-Edge Based Structured Light ", ICPR '02, Vol. 3, pp. 30645-30648, 2002 a, Process for 3D detection of an object by means of structured Known light. It is a means of a projector Color pattern including a redundant code with known projected projection data on the surface of an object and the object with aufprojiziertem color pattern with a camera from a direction deviating from the direction of projection added. By decoding of the color pattern on each Pixel of the camera image, the associated three-dimensional Coordinates of the object surface by means of triangulation be determined. This method allows a Portion of the surface of the object with a video image to reconstruct.

0006From JP 2001108421 A is a 3D scanner for three-dimensional Detecting an object known. rotated when scanning the object with a reference object, on which marks are attached. So be different views of the object and the reference object photographed, wherein the Photos by viewing the markings on the reference object to a three-dimensional computer model to be assembled. A disadvantage of the known method, for some Applications inadequate compliance of the computer model with the real object.

0007Object of the present invention is a method and provide an all-round scanner, with which an object and in particular an ear impression in a relatively simple and cost-effective manner with the preparation of a hearing aid shell required accuracy in three dimensions can be detected.

0008This object is achieved by a method for three-dimensional Detecting an object having the characteristics of Claim 1. Furthermore, the object is achieved by a full-Scanner according to claim 15th

0009For three-dimensional detection of an object according to the invention are at least a projector, a camera and Means for rotating the projector and the camera relative to the object is necessary. is through the projector a two-dimensional Pattern, for example a color pattern, the redundant one contains code with known projection data on the Surface of the object projected. The aufprojizierte color pattern is then reacted with a camera such as a CCD camera, from a direction deviating from the direction of projection Direction taken. By decoding of the color pattern of each pixel of the camera image, the associated three-dimensional Coordinates of the object surface by means of triangulation certainly.

0010To enable a three-dimensional panoramic view, rotates the object relative to the projector and the camera. Preferably the object is this, on a turntable. Between two shots as the turntable revolves around a predetermined angle, so that a plurality, for example 60, pictures can be recorded per circumference. In a scan the object rotates generally once by 360 ° around the Axis of rotation. Target for an object only a partial area are digitized, so the object can also be a Angles are rotated less than 360 °. Furthermore, it is also possible to increase the accuracy to be formed of 3D model more than a complete revolution in the detection of of an object is running. A termination criterion for the scan are then, for example, five fully executed Revolutions of the object.

0011Thus from these frames a coherent all-round view the object can be generated, it is advantageous if the 3D data of the individual images to a common coordinate system be based. For the purpose required Calibration in accordance with the invention on the scanner marks mounted opposite to its position when scanning not change the object. In the use of a turntable the markings are preferably on the Rotary plate or at the edge of the turntable. The marks are designed such that in each camera image in a specific Of these marks is visible and from these Markings of the rotation angle of the object relative to the projector and the camera clearly and with the required Accuracy can be removed. A higher number of Marks thereby increasing the accuracy of the 3D reconstruction.

0012Advantageously, the position of the moving object with the markings with respect to a "world coordinate system" once accurately determined and communicated to the evaluation system. Then the relative position of the object to the projector and the camera or the angle of rotation of the turntable from the position and the Coding recorded in the object image in the marks Coordinate system are determined. successively recorded Single image or gained from 3D data sets can simply by selecting the appropriate coordinate transformation joined to the overall view in the "world coordinate system" will.

0013The invention provides the advantage that in a simple and cost-effective Way synchronization of the still image shooting is achieved with the rotational movement of the object, without this highly accurate and correspondingly expensive mechanism is required. are from a user of the all-scanner not to perform calibration or adjustment operations, except the attachment of the object to be measured on the Turntable. It was therefore an easy to use, but yet highly accurate and cost measurement option created the 3D wraparound surface of an object. The all-Scanner according to the invention is therefore as excellent for Use suitable by an audiologist, who from a patient created an ear impression and by the scanner digitized three-dimensionally, so that the model data obtained via data transmission (e-mail or the like) directly to Manufacturer of a housing shell can be transmitted. In this way, the time and costs in the manufacture of Hearing aid housing savings.

0014In one embodiment of the invention at a Rotation of the object to the camera and the projector relative several overlapping object images included. there are then in successive object images each more the same markings visible. Using the common visible markings are combined, the object images such that a so-called image composite is formed. A accurate measurement of the markers is not required for this, which makes the production of the system simplified.

0015By means of a "bundle" called and made photogrammetry known method, the relative Camera coordinate of each recording are determined. A few in the "world coordinate system" measured markings serve the image combined with this in relation to set. After this step, the individual object images simply by selecting the appropriate coordinate transformation are joined to the overall view. To calculate simplify, there are two axes of the "world coordinate system" in the plane spanned by the turntable level and the third axis of the "world coordinate system" falls with the axis of rotation of the turntable together.

0016The labels are preferably designed such that it contain a coding with the periphery of 1-n, for example, in the form a binary code. Advantageously comprise the markings some measurement positions (corners, lines, circles or the like). The marks recorded in the object images are in each object image by a suitable image processing software detected automatically decoded and measured. Preferably, the marks are designed such that for each object image by viewing the markings contained therein an unambiguous assignment of the spatial position in relation to the camera and the projector is possible.

0017A development of the invention provides that the rotational axis, to the object relative to the projector and the Camera rotated, pivoted relative to the projector and the camera can be. In the use of a turntable This is achieved most simply by that the turntable in at least one direction by a certain angle is tilted. This brings particular advantages when digitizing from ear impressions, as these rugged relatively could be. By the pivoting of the axis of rotation can shading and thus gaps or inaccuracies in to prevent the three-dimensional computer model.

0018are In an advantageous embodiment of the invention the markers are arranged and configured such that from each object image in addition to the rotation angle and the angle by which the rotation axis is pivoted relative to an initial position is, can be detected. The starting position thereby, the Location of rotation axis in the preceding object image or an initial position of serve.

0019In an alternative embodiment of the invention are at least two mutually offset cameras exist, so that the object simultaneously from different angles can be received. The cameras are relative the axis of rotation of the object to be detected in different Height mounted, so that even undercuts the Object that when using only one camera to flaws would result in the computer model, the more Camera can be recorded. To pivotal movement of the can thereby dispense rotation plate relative to the cameras will. Advantageously, in addition to a second camera also a second projector used so that each through a Camera Projector pair object images are formed.

0020The self-calibration feature an all-scanner according to the invention has the advantage that all individual 3D object images assembled simply to a 3D panoramic image can be. Here are no great demands on the Constancy of rotational movement detected. A synchronization of the Rotational movement with the image recording is not required. It can therefore fall back to a low-cost mechanics will. The accuracy of the 3D acquisition can easily Increasing the number of pictures will increase per revolution.

0021By a large number of the measurement data and in particular by overlapping object images increases the robustness and Accuracy of measurement significantly.

0022The invention is described by means of embodiments described. Show it:<sl><li>Figure 1 is a schematic diagram of the 3D detection of an object using color-coded, structured light,</li><li>2 shows the basic diagram of a scanner according to the invention, </li><li>Figure 3 shows a scanner in accordance with the invention in perspective View,</li><li>Figure 4 shows the scanner of figure 3 with an opposite 3 tilted axis of rotation,</li><li>Figure 5 shows the scanner of Figures 3 and 4 with a housing, and</li><li>Figure 6 shows an alternative embodiment of a scanner with two cameras.</li></sl>

00231 shows a device 1 is shown that this serves, the three-dimensional object coordinates of a surface 2 of an object to be detected to determine three.

0024The device 1 comprises a projector 4, the color pattern A 5 on the surface 2 of the object to be detected 3 projected. In the case illustrated in Figure 1 is the lying color pattern 5 of a series of side by side Streaks composed. However, it is also conceivable for a two-dimensional color pattern instead of the shown in Figure 1 dimensional color pattern 5 to use.

0025In the embodiment shown in Figure 1 can each Point P of the surface 2 of the object 3 a projection plane g are assigned. By the color pattern 5 are thus Projection data encoding. The onto the surface 2 of the object 3 projected color pattern 5 is in by a camera 6 7, an image is converted, in which the point P on the surface 2 is transformed into the point P '. With a known arrangement the projector 4 and the camera 6, in particular at known length of a base section 8, can by triangulation the three-dimensional space coordinates of the point P on the surface 2 are calculated. The requisite data reduction and evaluation is an evaluation of 9 made.

0026In order to determine the three-dimensional spatial coordinates of Point P on the surface 2 of a single image 7 also to allow, when the surface 2 of the object 3 has deep cracks and occlusions, the color pattern is 5 constructed so that the coding of the projection planes g is as robust as possible against errors. Further, by Coding errors, based on the coloring of the object, are eliminated.

0027In the case of the embodiments illustrated in Figure 1 the colors of the color pattern 5 described by the RGB model. The changes take place of the color values ​​of the color pattern 5 by changes of the color values ​​in each color channel R, G and B.

0028The color pattern is then satisfy the following conditions:<ul><li>In each color channel, only two color values ​​are used. In particular, in each color channel is in each case the minimum value and the maximum value is used so that in the RGB model a total of eight colors are available.</li><li>Within a codeword, each color channel at least a color change on. This condition allows the decoding the individual code words.</li><li>Adjacent color elements differ in at least two color channels. This condition is particularly to fault tolerance especially against indentations to ensure.</li><li>The individual code words of the color pattern 5 have a nontrivial on Hamming distance. This condition serves the fault tolerance in decoding the projection planes g to increase. </li><li>The color changes to code words with a non-trivial Hamming distance summarized.</li></ul>

0029An example of the color pattern 5 may be mentioned, which satisfies the above five conditions. This color pattern 5 refers to the RGB model with a red Color channel R, a green color channel G and a blue color channel B. Since color values ​​in each color channel only in each case the minimum value and maximum value may assume a total eight mixed colors available, each of which the following Numbers are assigned:<tables><table><tgroup cols="2"><tbody><row><entry align="left">black</entry><entry align="left">0</entry></row><row><entry align="left">blue</entry><entry align="left">1</entry></row><row><entry align="left">green</entry><entry align="left">2</entry></row><row><entry align="left">cyan</entry><entry align="left">3</entry></row><row><entry align="left">red</entry><entry align="left">4</entry></row><row><entry align="left">magenta</entry><entry align="left">5</entry></row><row><entry align="left">yellow</entry><entry align="left">6</entry></row><row><entry align="left">White</entry><entry align="left">7</entry></row></tbody></tgroup></table></tables>

0030For the code words of the color values ​​was a length of four selected color strips with adjacent codewords respectively overlap with three streaks.

0031Even the color changes were assigned numerical values. As in each of the three color channels of the color value will remain the same, fall can or increase, resulting a total of 27 different Color changes of the mixed color, each of which a number was assigned to 0-26. The length of the color changes assigned code words was equal to three color changes chosen with adjacent codewords respectively two color changes overlap.

0032the following sequence of numbers was by a search algorithm found that describes an embodiment of the color pattern 5, which satisfies the above five conditions: 1243070561217414270342127216534171614361605306352717072416305 250747147065035603634743506172524253607

0033In the chosen embodiment, the first Codeword of the digits 1243, the second codeword from the Numerals 2430 and the third codeword of the digits 4307th The embodiment shown provides a very robust Coding is.

00342 shows the basic diagram of an all-round scanner is under of the invention is illustrated. The scanner includes a Turntable 10 which is mounted rotatably about its axis of symmetry is. On the turntable is a according to the individual anatomical Circumstances a hearing aid wearer gearteter ear impression 11 attached. The ear impression 11 is for manufacturing individually formed shell of a worn in the ear Hearing aid are digitized. The detection of the ear impression by means of coded illumination and triangulation. To this end, the all-round scanner comprises a projector 12, of a color-coded pattern onto the surface of the ear impression 11 projected. The image projected onto the surface of the ear impression 11 Color pattern is in by a CCD camera 13, an image the ear impression 11 converted. By the rotational movement of the Turntable 10 may consist of a plurality of such pictures be included different viewing angles. Thus the individual pictures of the respective viewing angle can be assigned, are at the outer edge of the turntable 10 marks 14 attached. In addition to the ear impression 11 is in each image a number of these markers 14 captured. The images of the markers 14 are in the Object images through a computer 15 with a suitable Image processing software automatically detects, decodes and measured. Based on the angle information gained is from the individual images a three-dimensional Computer model of the ear impression 11 is calculated. The computer 15 is preferably not part of the actual all-scanner, that is, not with the turntable 10, the projector 12 and the Camera 13 disposed in a common housing. Much more can as a computer 15 with an external, high-performance PC suitable software used. The all-round scanner features then via an interface for connection to the computer 15th

0035Figure 3 shows the illustrated in Figure 2, in principle image All-round scanner in perspective. are also from the turntable 10, a projector 12 and a CCD camera 13 seen each other in the respective location. It is further in figure 3 the drive unit for the turntable 10 to remove. This comprises a motor 16 which via a gear wheel 17 and a toothed belt 18 the turntable 10 drives. furthermore is shown in Figure 3, a mechanism represented by the when the turntable 10 in addition to the rotational movement of a Pivoting movement is possible. The pivot axis 19 runs in the embodiment by the intersection of the axis of rotation 20 with the surface of the turntable 10. Also, the Pivotal movement takes place in the embodiment automatically shown by an electric drive, wherein, in the Embodiment, the motor 16 both the rotation movement as the pivoting movement causes. The rotation of the Turntable 10 is namely an associated gear 21A driven, which in a fixed manner in the housing of the scanner anchored dental piece 21B engages and thereby the pivoting movement the drive unit with the motor 16 and the toothed belt 18 leads. Furthermore are visible at the edge of Turntable 10 mounted markers 14, by means of which the exact angle of rotation of the turntable 10 and thus a it supported object (see FIG. 2) with respect to the projector 12 and the camera 13 from the generated images can be determined.

0036Advantageously, there is the axis of rotation at the beginning of Detecting an object in the designated starting position. This can be accomplished in that at the Housing of the all-scanner a housing cover (not shown) is pivotally mounted. Before placing a Object on the turntable 10 it must first housing cover be opened. When opening this housing cover then the entire rotary unit with the engine 16 and the turntable 10 by an appropriate mechanism (not shown), into their starting position. At the start a scan is thus the turntable 10 in the in Figure 3 illustrated starting position, until he finally after several revolutions, the end position shown in Figure 4 occupies. In the final position of the engine 16 is automatically stopped. blank With the markings in the object images to each image of the angle of rotation and the angle by which the Turntable 10 is pivoted from its initial position, clearly remove. Thus, from the individual object images 3D model created with high accuracy.

0037Alternatively, the turntable 10 for performing the pivoting movement with a second motor (not shown) be connected. The pivotal movement can then also by the Calculator 15 are controlled so that the number of revolutions the turntable, in this in from a starting position an end position swings, is variable.

0038In the all-around scanner of figure 3, the turntable, the Drive unit of the turntable, the projector and the camera in a joint, shown in Figure 5 housing 30 accommodated. This provides the all-around scanner compact and easy-to-use unit. Also, the operator is very easy because the user in addition to the mounting of the object on the turntable 10, no further Calibration and adjustment operations must carry out. furthermore Figure 5 are still the two housing openings 31 and 32 for to remove the projector and the camera. Also includes the omnidirectional scanner or a cable 33 for connection to a Calculator.

0039An alternative embodiment of an all-round scanner according the invention is shown in FIG 6. In contrast to the previous Embodiments, the rotating plate 60 in this embodiment not swivel. To nevertheless complicated To detect objects with undercuts, the Scanner two superposed cameras 61 and 62, the object thus from different directions capture. Furthermore, the projector 63 is not as punctate Ray source configured. Rather, it is a coded Pattern starting from a vertical line from. Thus, the projection of the pattern is to all areas the object that are captured by the cameras, guaranteed. Alternatively, several projectors with punctate Radiation source (not shown) may be used. By using multiple cameras is a pivoting movement the turntable 60 lapsed and the drive unit can be compared to the preceding embodiments, simplify. Thus, in the embodiment shown in FIG 6 the turntable 60 directly (without the interposition of a toothed belt) driven.

0040Also in the all-around scanner of Figure 6 are all components encompassed by a common housing, so that this forms a compact and easy-to-use unit. Furthermore, a cost-effective, available in the market components (CCD cameras, projector), and in particular a simple mechanism be used.