Method and apparatus for determining metric data of one or more features of an object and computer program

Abstract

Method for determining metric data of at least one feature (3) of a measurement object (7), with an illumination consisting of at least one light source (2a, 2b, 2c) and at least one camera (1) recording the measurement object (7), in particular the feature (3) of the measurement object (7), and at least one coordinate measuring unit, in particular a 3D digitizer, as well as an evaluation unit (6), wherein the position and orientation of the camera (1) and the coordinate measuring unit relative to each other are known.

Description

[0001] The present invention relates to a method and a device for determining metric data of at least one feature of a measured object with a light source, at least one camera, at least one coordinate measuring unit and an evaluation unit.

[0002] The present invention further relates to a computer program with instructions which, when the program is executed by the evaluation unit by at least one processor, cause this at least one processor and / or further processors to execute the method according to the invention with the device according to the invention.

[0003] To join body components, it is necessary that both the components themselves and their connecting points are of the correct size. This ensures that they can be joined, meaning one component fits onto the other, while simultaneously preventing excessive play between the connecting elements. However, during manufacturing, wear and tear on the tools used to produce the components can lead to the desired tolerances no longer being met. Therefore, the components and their connecting elements are inspected using coordinate measuring machines, particularly 3D digitizers, which can measure objects three-dimensionally.

[0004] The 3D data generated by the coordinate measuring units can be acquired either tactilely or optically. 3D digitizers utilize optical methods such as triangulation with at least two cameras or one camera and a projector, time-of-flight measurement (TOF), lidar, confocal measurement, etc. In most cases, the 3D digitizer includes active illumination for measuring the 3D data.

[0005] The features of an object to be inspected can include, for example, holes, bores, screw threads, bolts, or edges. A feature can consist of one or more edges. A round hole consists of one edge running around the entire perimeter, a rectangular hole would consist of four edges, and so on. Edges are characterized by their significant curvature compared to the rest of the object's surface.

[0006] The metric data of a feature can be, for example, the diameter of holes, the length of slots, the width of a step, etc. To determine the metric data with a 3D digitizer, the edge or, in the case of a hole, alternatively the walls must be measured. Previously, the 3D digitizer had to be moved around the edge or walls to capture the feature from different directions. However, with holes, for example, there is the problem that not much of the inner wall area can be captured, as it is only possible to measure into cavities to a limited extent. The inner wall is obscured by the opposite wall. Thus, many positions are necessary to obtain sufficient 3D data of the inner walls for determining the metric data of the feature, which results in an enormous amount of time spent capturing the feature. Capturing 3D data along the edge or...Measuring along a surface edge is also challenging. Artifacts appear extending beyond the edge, and sometimes even before it, which do not accurately represent the object's surface and are therefore unusable. To remove incorrect or unreliable data, the edge is detected in images, and the data extending beyond the edge or located at a certain distance from it is removed from the 3D data captured in the same position with the 3D digitizer. This can be done either by projecting the edge onto the 3D data or by marking the data as invalid directly in the images used to calculate the 3D data. The surrounding 3D data and the edge can then be used to determine the feature's metric data.Projecting the edge onto the 3D data is possible if the position and orientation between the camera that captured the image and the 3D digitizer that acquired the 3D data are known. A method for determining the edge of a feature is described, for example, in DE 10 2018 116 862 A1.

[0007] Edge detection is achieved by identifying light-dark transitions, as described, for example, in DE 10 2018 116 862 A1, or by using other common algorithms or edge filters (e.g., Canny edge filters) in the images. These light-dark transitions are particularly noticeable when there is a transition from an illuminated to an unilluminated area. However, with only one illumination source, this is usually only possible along a limited portion of the edge. To capture additional sections of the edge, sufficient for determining the feature's metric data, the 3D digitizer must again be positioned around the feature in various poses, and multiple images must be taken, which is correspondingly time-consuming.Furthermore, the data recorded at the various locations must be aligned, which can be prone to errors.

[0008] It is therefore an object of the present invention to provide a method and a device for determining metric data of one or more features of an object and a computer program for carrying out the method according to the invention with the device according to the invention, thereby solving the problems mentioned above.

[0009] Against this background, the invention proposes a method for determining metric data of at least one feature of a measurement object, comprising illumination consisting of at least one light source and at least one camera recording the measurement object, in particular the feature of the measurement object, and at least one coordinate measuring unit, in particular a 3D digitizer, as well as an evaluation unit, wherein the position and orientation of the camera and the coordinate measuring unit relative to each other are known, characterized by a first step involving aligning the at least one camera with the measurement object, in particular with the feature of the measurement object, and a second step with a sub-step in which an image of the feature in a first illumination configuration is captured with the at least one camera, such that one or more first shadows are generated, which are limited at first relevant edge regions of the feature.wherein the boundaries are recognizable in the image captured by the camera, and one or more further sub-steps in which an image of the feature is captured in an illumination configuration that differs from the previous illumination configurations with respect to the current camera pose, with which at least one camera is used, so that one or more further shadows are generated, which are limited at further relevant edge regions of the feature that differ from the previous relevant edge regions of the feature, but may partially overlap with the previous relevant edge regions, wherein the boundaries are recognizable in the image captured by the camera, and a third step, which is carried out temporally before, after or during the second step, for capturing 3D data of the object being measured, in particular the feature of the object being measured, with the coordinate measuring unit.

[0010] According to a further aspect of the present invention, a device for carrying out the method according to the invention is proposed with an illumination comprising at least one light source and at least one camera recording the object being measured, in particular the feature of the object being measured, and at least one coordinate measuring unit, in particular a 3D digitizer, as well as an evaluation unit, wherein the position and orientation of the camera and the coordinate measuring unit relative to each other are known.

[0011] Furthermore, a computer program is proposed with instructions which, when the program is executed with the evaluation unit by at least one processor, cause this at least one processor and / or further processors to execute the inventive method with the inventive device.

[0012] The advantage of the present method or device is that the different lighting configurations create a shadow boundary in many different areas along one or more edges without requiring camera movement, thus saving the time associated with camera repositioning. Ideally, the amount of shadow boundary in a single camera or 3D digitizer pose is sufficient to determine the metric data of the feature.

[0013] The relative positions and orientations of the camera and the coordinate measuring unit must be known so that the 2D data (i.e., the image data captured by the camera) can be transformed into the coordinate system of the 3D data captured by the coordinate measuring unit. Alternatively, the 3D data can also be transformed into the coordinate system of the 2D data. The relative positions and orientations of the camera and the coordinate measuring unit can be determined, for example, by calibrating the device. For details on performing coordinate transformations, see Luhmann, Robson, Kyle, Boehm, Close Range Photogrammetry and 3D Imaging, Second Edition, Chapter 2, ISBN 978-3-1110-2986-3.

[0014] To carry out the procedure, it is not absolutely necessary to record the entire characteristic. It may also be sufficient to record only a part of the characteristic.

[0015] Preferably, the edge areas are determined using an evaluation unit.

[0016] The above-mentioned task has therefore been completely solved.

[0017] According to a further embodiment, one or more optional fourth steps are carried out by realigning at least one of the cameras to the object being measured, in particular to the feature of the object being measured, and repeating the second and third steps.

[0018] If the number of shadow boundaries is insufficient for determining the metric data of the feature, one of the cameras can be realigned, and optionally the lighting configuration can also be changed. This allows shadow boundaries or edge areas to be captured in images that were previously obscured by the lighting or the camera and therefore could not be recorded.

[0019] According to a further embodiment, at least one boundary of a shadow along a relevant edge area is generated in at least one of the images for all relevant edge areas necessary for determining the metric data of the feature to be evaluated, and the evaluation unit uses the boundary of the shadow in the images to detect the location of one or more relevant edge areas of the feature, and uses the location of the relevant area(s) in the images as well as the 3D data to determine the metric data of the feature.

[0020] In order to determine the metric data of the feature with sufficient accuracy, it is necessary, on the one hand, to create a boundary of a shadow along the edge areas on all relevant edge areas, i.e., all areas necessary for a sufficiently accurate determination, and on the other hand, the 3D data of the coordinate measuring unit are also required, as explained, for example, in DE 10 2018 116 862 A1.

[0021] According to a further embodiment, different lighting configurations are created by moving at least one light source.

[0022] Instead of using many light sources to create different lighting configurations, it is sufficient to provide only one or a few light sources that can be moved.

[0023] According to a further embodiment, different lighting configurations are created by switching on and off or by using different brightness levels at least one of at least two light sources.

[0024] This has the advantage that mechanical movements for moving the light sources are unnecessary, thus saving time. In the case of two light sources, for example, a first shadow boundary can be created along a first edge area by turning one light source on and the second off. A second shadow boundary along a second edge area can then be achieved with a second lighting configuration by turning the first light source off and the second on.

[0025] According to a further embodiment, at least two of the images recorded in the second step are combined to form a synthetic image in order to determine the position of one or more relevant edge regions, or the position of an entire edge region is determined based on the positions of the respective relevant edge regions from the respective images.

[0026] Depending on the feature, it may be advantageous to combine individual images into a synthetic image to determine edge regions or the entire edge, or it may be advantageous to first evaluate individual images, i.e., to determine the edge regions in each image individually, and then combine these edge regions into a single edge. A combination of both approaches is also conceivable.

[0027] According to a further embodiment, the at least one light source is a point light source.

[0028] Point light sources offer the advantage of creating a very sharp boundary between the shadow and the illuminated area. This allows for very precise edge definition. However, other shaped light sources can also be used.

[0029] According to a further embodiment, the light source or light sources illuminate the object being measured and / or the surroundings of the feature and / or the feature homogeneously.

[0030] The homogeneous illumination in the lit area produces a low-noise grayscale level in the bright areas of the images, which allows for better detection of shadow boundaries and thus edges. As a result, the contrasts remain approximately the same along the edge.

[0031] According to a further embodiment, at least one of the light sources is a projector, in particular a projector of the 3D digitizer.

[0032] In 3D digitization, active lighting is typically used to display structured light, such as a structured light projector, for determining the 3D data. This lighting can also be used as a light source for edge definition, thus saving a separate light source, since the active lighting performs the tasks of both edge definition and 3D data definition.

[0033] According to another embodiment, the at least one camera is a camera of the 3D digitizer.

[0034] This eliminates the need for a separate camera used solely for edge detection, resulting in a more cost-effective overall system. Typically, the coordinate system of the 3D digitizer is identical to that of its camera. In this case, a coordinate transformation between the 2D and 3D data can be advantageously avoided, as they already reside in the same coordinate system since they are generated by the same camera.

[0035] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also individually or in other combinations, without leaving the scope of the present invention.

[0036] Furthermore, it is understood that the method features (or device features) defined in the dependent claims for the method (or device) for determining metric data of features of a measured object can also be used in the same or equivalent manner as device features (or method features) for the device (or method) according to the invention, without being listed separately here again as device features (or method features).

[0037] The indefinite term "a", "an", "a", etc., is not to be understood as a numeral within the meaning of the present invention, but rather as an indefinite term meaning "at least one", "at least one", "at least one", etc. Thus, the features designated by "an element" also include multiple such elements, such as multiple light sources or multiple 3D digitizers, cameras, features, or edges, etc. Furthermore, other elements are not excluded.

[0038] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. They show: Fig. 1 a block diagram to illustrate the method according to the invention Fig. 2 A schematic representation of a 3D digitizer with a camera and light sources for recording a hole in a measuring object. Fig. 3 a picture of an illuminated hole taken with a camera; Fig. 4a,b a schematic representation of a hole located below a light source to illustrate the light reflections for a glossy reflective surface ( Fig. 4a), and a surface that is diffusely reflective ( Fig. 4b).

[0039] In Fig. Figure 1 shows a block diagram intended to illustrate the inventive method for determining metric data of at least one feature 3 of a measurement object 7, with illumination consisting of at least one light source 2a, 2b, 2c, etc., and at least one camera 1 recording the measurement object 7, in particular feature 3 of the measurement object 7, and at least one coordinate measuring unit, in particular a 3D digitizer, as well as an evaluation unit 6, wherein the position and orientation of the camera 1 and the coordinate measuring unit relative to each other are known. One possible sequence of steps is shown. However, other sequences of steps are also possible.The position and orientation of camera 1 to the coordinate measuring unit must be known so that 2D data from camera 1, which are calculated from the images with the evaluation unit 6, such as the course of a boundary 8 of a shadow 9, and 3D data from the coordinate measuring unit can be transferred into a common coordinate system.

[0040] In a first step A, at least one camera 1 is aligned with the object being measured, in particular with feature 3 of the object being measured 7. The camera 1 can be used as an independent system, but it can also be the camera 1 of the 3D digitizer (the coordinate measuring unit) and thus perform several tasks.

[0041] The second step B is divided into two sub-steps BA and BB. In sub-step BA, an image of the feature 3 is captured in a first lighting configuration with the at least one camera 1, so that one or more first shadows 9 are generated, which are bounded at first relevant edge regions 5a of the feature 3, the boundaries 8 being recognizable in the image captured with the camera 1.In one or more further sub-steps BB, an image of feature 3 is captured with at least one camera 1 in a lighting configuration that differs from the previous lighting configurations in relation to the current camera pose, so that one or more further shadows 9 are generated, which are bounded at further relevant edge regions 5b of feature 3, which differ from the previous relevant edge regions 5a of feature 3, but may partially overlap with the previous relevant edge regions 5a, the boundaries 8 being recognizable in the image captured with camera 1.

[0042] In a third step C, 3D data of the object being measured 7, in particular feature 3 of the object being measured 7, is acquired using the coordinate measuring unit. Fig. 1. The third step C follows step B, but it can also be performed before or during step B.

[0043] Optionally, in one or more fourth steps D, a realignment with at least one of the cameras 1 onto the object 7, in particular onto feature 3 of the object 7, can take place and steps B and C can be repeated.

[0044] Using the recorded images, at least one boundary 8 of a shadow 9 along a relevant edge area 5a, 5b can be generated in at least one of the images on all relevant edge areas 5a, 5b that are necessary for determining the metric data of the feature 3 to be evaluated, and the boundary 8 of the shadow 9 in the images can be used with the evaluation unit 6 to detect the position of one or more relevant edge areas 5a, 5b of the feature 3, and the position of the relevant area(s) in the images as well as the 3D data can be used to determine the metric data of the feature 3.

[0045] The coordinate measuring unit can be, in particular, a 3D digitizer. This usually includes a camera 1 and active lighting for creating 3D data, for example, using triangulation or time-of-flight measurement methods.

[0046] Fig. Figure 2 schematically shows an embodiment of the device according to the invention with a camera 1 and two light sources 2a and 2b, wherein in this embodiment one of the light sources 2a or 2b, as well as the camera 1, performs a dual function. By using at least one of the light sources 2a or 2b as active illumination or as a projector in combination with the camera 1, a 3D digitizer can be realized for capturing 3D data of the measurement object 7 or the feature 3, which in this embodiment represents a hole. Furthermore, the camera 1 is used in a second function to create images of the feature 3 under different illumination configurations, so that the edge regions 5a, 5b of the feature 3 are detected in the images. This could also be done with a separate camera 1.A first lighting configuration can be achieved by switching on light source 2a and switching off light source 2b, so that a shadow 9 is cast on wall 4a of feature 3, bounded at edge region 5a, and edge region 5a can therefore be detected in the captured image by the evaluation unit 6, while wall 4b of feature 3 is illuminated, so that there is no boundary 8 of a shadow 9 at edge region 5b, and therefore edge region 5b cannot be detected in the image. In a second lighting configuration, if light source 2a is switched off and light source 2b is switched on, a shadow 9 is cast on wall 4b of feature 3, bounded at edge region 5b, while no shadow 9 is cast on wall 4a of feature 3, and therefore there is no boundary 8 of a shadow 9 at edge region 5a.

[0047] The evaluation unit 6 analyzes the images from camera 1 and determines the profiles of edge regions 5a and 5b in the images. Based on this 2D data and the 3D data, the metric data of the depicted feature 3 are determined. The evaluation unit 6 can be part of a computer that can also control camera 1, the coordinate measuring unit, and the light sources 2a and 2b. Alternatively, the evaluation unit 6 can also be part of the 3D digitizer. If the amount of data for edge regions 5a and 5b is insufficient, one or more additional lighting configurations can be created so that the shadow 9 is limited at further points along the edge, allowing these additional points to be detected. These additional lighting configurations can be generated, for example, by additional light sources 2c, 2d, etc. (not shown).

[0048] The light sources 2a, 2b, 2c, etc. can be point sources, as these can produce a sharp boundary 8 of the shadow 9. However, light sources 2a, 2b, 2c, etc. can also be used in other shapes. Light sources 2a, 2b, 2c, etc., or lighting configurations that homogeneously illuminate the area around feature 3, can also be used. This can be advantageous for detecting the boundary 8 of the shadow 9 and thus the edge regions 5a, 5b, as the gray value differences between shaded and illuminated areas in the images along the edge regions 5a, 5b are similar.

[0049] Furthermore, the light sources 2a, 2b, 2c, etc. can be, in particular, LED light sources that emit monochromatic light, especially blue light. This can be advantageously used to eliminate interfering ambient light, especially by using camera 1 with a color filter that only allows the monochromatic light from the light sources 2a, 2b, 2c, etc. to pass through.

[0050] Fig. Figure 3 shows a recording of a feature 3 with a camera 1, where the feature 3 in this recording depicts a hole, as it appears in Fig. Figure 2 shows the shadow 9 and its boundary 8, which is bounded on the left by edge region 5a. This would correspond to the lighting configuration in which light source 2a is on and light source 2b is off. The shadow 9 is also bounded on the right; however, this boundary 8 of the shadow 9 runs along the bottom of the hole and therefore does not represent a boundary 8 that runs along an edge region 5a, 5b. To distinguish a boundary 8 that runs along an edge region 5a, 5b from a boundary 8 that does not, plausibility can be checked. For example, the position of light sources 2a, 2b, 2c, etc., relative to camera 1 can be used for this purpose.In this case, the activated light source 2a is located on the left side of the image. Therefore, it makes sense to detect only boundaries 8 in the image that have a gradient from light to dark, and not from dark to light, approaching from the left. Alternatively, if the position of the light source 2a, 2b, 2c, etc., relative to camera 1 is not known a priori, but the shape of feature 3 is, the images of the two lighting configurations can be combined into a synthetic image, or the edge gradients of the two images can be combined. In this case, the boundary 8 along the edge of the round hole would have a circular or elliptical shape, while the boundary 8 on the ground would have a lens shape. However, the lens shape would not match the round hole, and therefore the boundaries 8 on the ground would be discarded.Furthermore, the 3D data can also be used to check whether a boundary 8 can be an edge area 5a, 5b.

[0051] Features 3 located below between the light sources 2a, 2b, such as the hole made of, can be measured according to the inventive method. Fig. 2, or even slightly off, like the hole made of Fig. 4a and Fig. 4b. As in the Fig. 4a and Fig. As shown in Figure 4b, when light source 2b is switched off and light source 2a is switched on, the wall 4a of the hole is still illuminated by light source 2a. However, the angle of incidence 18, which results from the perpendicular 17 of the surface of wall 4a and the incident light ray 12, is so large that only a small amount of light is reflected back into the camera 1, while more light is reflected back into the camera 1 from the surface 10 of the measuring object 7. This is due to the lengths of the portion of the backscattered rays 13 and 14 that lies within the ellipse 15 and 16 for a glossy reflecting surface ( Fig. 4a) and by the lengths of the fraction of the backscattered rays 13 and 14 that lies within the circles 19 and 20 for a diffusely reflecting surface ( Fig. 4b) shown, where the lengths correspond to the radiation intensity. In the case of a glossy reflective surface ( Fig.4a) The distribution of reflected radiation results from a component of diffusely reflected radiation and a component of specularly reflected radiation. For diffusely reflected radiation, the distribution is spherical according to Lambert's law, or circular in side view. The distributions of the specular radiation can be represented by an ellipsoid, or in side view by an ellipse 15, 16, where the principal axis of the ellipsoid or ellipse 15, 16 is oriented according to the angle of reflection for specularly reflected radiation.Since the length of the radiation 13 and 14 backscattered into the camera 1, which lies within the ellipse 15 (within the circle 19), is greater than within the ellipse 16 (within the circle 20), the surface adjacent to the ellipse 15 (to the circle 19) appears brighter in the camera 1 than the surface adjacent to the ellipse 16 (to the circle 20), so that the wall 4a appears darker compared to the surface 10, which can be recognized as a shadow 9 in the image of the camera 1, and the method according to the invention can be carried out.

[0052] The method can therefore also be applied if the geometry of feature 3 allows a sufficiently high light-dark difference along the edge through the corresponding lighting configurations, where light-dark difference means the difference between gray values ​​of the light area on one side of the edge to the gray values ​​of the dark area on the other side of the edge in the recorded image.

[0053] It is understood that the exemplary embodiments shown here serve only as a schematic illustration of the principle and method of implementation of the present invention. Various functional and structural modifications are possible without departing from the scope of the present invention. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 116 862 A1 [0006, 0007, 0020] Cited non-patent literature

[0000] Luhmann, Robson, Kyle, Boehm, Close Range Photogrammetry and 3D Imaging, Second Edition, Chapter 2, ISBN 978-3-1110-2986-3

[0013]

Claims

[1] Method for determining metric data of at least one feature (3) of a measurement object (7), with an illumination consisting of at least one light source (2a, 2b, 2c) and at least one camera (1) recording the measurement object (7), in particular the feature (3) of the measurement object (7), and at least one coordinate measuring unit, in particular a 3D digitizer, as well as an evaluation unit (6), wherein the position and orientation of the camera (1) and the coordinate measuring unit relative to each other are known, characterized by a first step A by aligning the at least one camera (1) with the object being measured (7), in particular with the feature (3) of the object being measured (7); a second step B with a sub-step BA in which an image of the feature (3) is captured in a first illumination configuration with the at least one camera (1) such that one or more first shadows (9) are generated, which are bounded at first relevant edge regions (5a) of the feature (3), wherein the boundaries (8) are recognizable in the image captured with the camera (1); and one or more further sub-steps BB, in which an image of the feature (3) is taken in a lighting configuration that differs from the previous lighting configurations of the other sub-steps (BA, BB) with respect to the current camera pose, with which at least one camera (1) is taken, so that one or more further shadows (9) are produced, which are bounded at further relevant edge regions (5b) of the feature (3) that differ from the previous relevant edge regions (5a) of the feature (3) of the other sub-steps (BA, BB), but may partially overlap with the previous relevant edge regions (5a), wherein the boundaries (8) are recognizable in the image taken with the camera (1); a third step C, which is carried out before, after or during step B, to acquire 3D data of the object being measured (7), in particular of the feature (3) of the object being measured (7), with the coordinate measuring unit. [2] Method according to claim 1 with one or more optional fourth steps D comprising realigning at least one of the cameras (1) to the object being measured (7), in particular to the feature (3) of the object being measured (7), and repeating steps B and C. [3] Method according to any one of claims 1 to 2 characterized by, that in at least one of the images at all relevant edge regions (5a, 5b) necessary to determine the metric data of the feature (3) to be evaluated at least one boundary (8) of a shadow (9) along a relevant edge region (5a, 5b) is generated and the evaluation unit (6) uses the boundary (8) of the shadow (9) in the images to detect the location of one or more relevant edge regions (5a, 5b) of the feature (3), and the location of the relevant edge region(s) (5a, 5b) in the images as well as the 3D data are used to determine the metric data of the feature (3). [4] Method according to any one of claims 1 to 3 characterized by , that different lighting configurations are created by moving at least one light source (2a, 2b, 2c). [5] Method according to any one of claims 1 to 4 characterized by, that different lighting configurations are created by switching on and off or by different brightness levels at least one of at least two light sources (2a, 2b, 2c). [6] Method according to any one of claims 1 to 5 characterized by , that at least two of the images taken in step B are combined to form a synthetic image in order to determine the location of one or more relevant edge regions (5a, 5b), or the location of an overall edge region is determined based on the locations of the respective relevant edge regions (5a, 5b) from the respective images. [7] Method according to claim one of claims 1 to 6, wherein only a 3D digitizer consisting of at least one projector and at least one camera is used to carry out the method steps. [8] Device for determining metric data of at least one feature (3) of a measurement object (7), comprising an illumination consisting of at least one light source (2a, 2b, 2c) and at least one camera (1) recording the measurement object (7), in particular the feature (3) of the measurement object (7), and at least one coordinate measuring unit, in particular a 3D digitizer, as well as an evaluation unit (6), wherein the position and orientation of the camera (1) and the coordinate measuring unit relative to each other are known, wherein the device is used to carry out the methods according to claims 1 to 7 and / or wherein the at least one coordinate measuring unit is configured to determine the 3D data of the measurement object (7), in particular the feature (3), and different illumination configurations are realized with the illumination for a given camera pose in relation to the measurement object (7), so that the measurement object (7), in particular the feature (3) of the measurement object (7),Shadows are created that are bounded at different edge areas (5a, 5b), and the different edge areas (5a, 5b) are recorded with the camera (1). [9] Device according to claim 8, wherein the at least one light source (2a, 2b, 2c) is a point light source (2a, 2b, 2c). [10] Device according to one of claims 8 to 9, wherein the light source (2a, 2b, 2c) or the light sources (2a, 2b, 2c) homogeneously illuminate the object being measured (7) and / or the surroundings of the feature (3) and / or the feature (3). [11] Device according to one of claims 8 to 10, wherein at least one of the light sources (2a, 2b, 2c) is a projector, in particular a projector of the 3D digitizer. [12] Device according to one of claims 8 to 11, wherein the at least one camera (1) is a camera (1) of the 3D digitizer. [13] Computer program comprising instructions which, when the program is executed with the evaluation unit (6) by at least one processor, cause this at least one processor and / or further processors to execute the method according to one of claims 1 to 7 with the device according to one of claims 8 to 12.

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