Method and system for generating three-dimensional image of at least one partial section of row of teeth, computer program product and mirror element

Abstract

The invention relates to a method and a system for generating three-dimensional images (A, A2) of at least a partial section of a row of teeth (Z) using a stereo camera system (1) of a surgical microscope (2), and a computer program product, in which the stereo camera system (1) comprises a first image capture device (5a) and a further image capture device (5b), in the image (I5a) generated by the first image capture device (5a) and in the image (I5b) generated by the other image capture device (5b), a respective imaged image (S5a, S5b) is detected, said imaged image being provided by a mirror element (3) arranged in a capture area (4) of the stereo camera system (1), the first image capture device (5a) and the further image capture device (5b) are arranged such that a mirror image of at least one partial section of the row of teeth (Z) can be imaged by the first image capture device (5a) and the further image capture device (5b), b. Determining a pose (P) of the mirror element (3), c. Determining a three-dimensional image (A, A2) on the basis of at least the imaged mirror image (S5a, S5b) and the pose (P) of the mirror element (3).

Description

Technical Field

[0001] The invention relates to a method and a system for generating a three-dimensional image of at least a partial section of a row of teeth using a stereo camera system of a surgical microscope, and to a computer program product and a mirror element for generating a three-dimensional image. Background Art

[0002] In dentistry, among other things, dental impressions are made, particularly in the context of restorative treatments, such as implants, or orthodontic treatment. These are used, for example, to determine the bite position and / or jaw position, particularly to document this at different treatment times. Dental impressions are also important as a basis for the planning and production of implants and dental braces / spontes.

[0003] As is known, a plastic material is pressed onto a row of teeth in order to produce a dental impression. After a waiting period of typically a few minutes, the dried material can then be removed from the row of teeth, providing a negative model of the row of teeth. This negative model can then be used to create a model of the row of teeth, such as a plaster model, which can be used in the development of the above-mentioned applications. In fact, when the material is removed from the row of teeth, slight changes to the negative model may occur, which leads to a deterioration in the accuracy of the model created thereby, which is problematic. In some cases, this deterioration may require repeated printing. Likewise, the time required to make the impression, especially the waiting time explained above, and the material consumption are generally undesirable aspects.

[0004] So-called intraoral scanners are also known, serving as an alternative to the graphic production of impressions using malleable materials. These use various measurement methods to generate a reconstruction of the surface of a row of teeth, as well as a digital model, which can then serve as the basis for the described applications. For example, it is conceivable that the model could serve as the basis for producing dental impressions using additive manufacturing methods, particularly 3D printers. Implants can also be produced in this way, which can then be placed in a timely manner.

[0005] Typically, intraoral scanners generate signals based on corresponding physical measurement principles using sensors, which are then processed to reconstruct or create a model. For example, known measurement principles for intraoral scanners include confocal laser scanning methods, triangulation methods, and tactile measurement methods. In order to create a model that is as complete and accurate as possible, all sides of a row of teeth or all sides of a tooth must be captured using (multiple) corresponding sensors. A disadvantage of known intraoral scanners is that, when used, a sensor carrier with one or more sensors used in each case needs to be inserted into the mouth in order to specifically capture the back side of a row of teeth, i.e., the side facing the inside of the mouth. This insertion can be very uncomfortable for the patient because it can cause unpleasant contact with the lips or other areas of the mouth. The patient may also feel that the deep insertion into the mouth (which may be necessary) is uncomfortable. Another disadvantage is that the sensor carrier or the part of the sensor carrier that is introduced into the mouth must be cleaned after use, which undesirably delays reuse.

[0006] For the person who creates the dental impression, i.e., for example, a dentist or orthodontist, such an intraoral scanner in the treatment room represents an additional device that, due to its size, disadvantageously reduces the space available in the treatment room. Furthermore, it can be difficult to integrate such an additional device into an established process, such as the process for creating a dental impression.

[0007] Surgical microscopes are also known. Such surgical microscopes are used by the user during treatment to provide an image, in particular a magnified image, of the treatment area (in particular a site). So-called stereoscopic surgical microscopes typically include two independent optical channels for beam guidance and can provide the user with an impression of the depth of the examination area. To this end, the beams guided in the two channels can be captured by the user's eyes via an eyepiece. As an alternative or supplement, digital surgical microscopes include two image capture devices, each of which captures the beam in one of the optical channels to generate an image, wherein a three-dimensional image is then provided to the user via a suitable display device based on the two images, the two images also being referred to as corresponding images hereinafter. In addition, other surgical microscopes that are capable of optically capturing depth information and providing a three-dimensional image of the treatment area are also known. For this purpose, optical detection systems that can provide depth information based on interferometry, triangulation, time of flight (TOF), or microlens arrays can also be used in surgical microscopes, in particular as an alternative to stereoscopic vision systems.

[0008] Accurate calibration of stereo camera systems is required to ensure correct delineation. Known calibration methods are used to determine intrinsic and extrinsic camera parameters, which are then used by image processing to ensure correct delineation. Intrinsic camera parameters describe parameters related to the respective camera / image capture device itself, such as its distortion. Extrinsic camera parameters describe the relationship, particularly spatial relationship, of the image capture devices and, therefore, the relationship of the camera images to one another. Such intrinsic and extrinsic camera parameters are known to those skilled in the art.

[0009] Known prior art includes DE 10 2020 133 627 A1, which discloses a method and an intraoral scanner for detecting the surface topography of a translucent object, in particular a dental object.

[0010] DE 10 2019 008 510 A1 is also known; it also discloses an intraoral scanner, in particular for three-dimensional scanning of upper or lower jaws with or without teeth and jaw components in the context of implant prostheses.

[0011] DE 10 2016 121 687 A1 is also known; it also discloses an intraoral scanner for digital dental impressions in the dental field and a method for generating digital dental impressions by means of an intraoral scanner.

[0012] EP 3 689 295 A1 is also known; it discloses a dental viewing device in which a so-called dental microscope is used.

[0013] Against this background, the technical problem that arises is to develop a method and a system for generating a three-dimensional image of at least a partial section of a row of teeth, as well as a computer program product and a mirror element for generating such a three-dimensional image, which allow for rapid, accurate, and patient-friendly generation of the three-dimensional image. Furthermore, improved integration into existing application processes and treatment rooms should be possible, which in turn reduces the costs associated with providing such a system. Summary of the Invention

[0014] The solution to the technical problem is evident from the subject matter having the features of the independent claims. Further advantageous configurations of the invention are evident from the dependent claims.

[0015] A method for generating a three-dimensional image of at least a partial section of a row of teeth using a stereo camera system of a surgical microscope is described. Surgical microscopes can be used for examining objects or magnified images of areas, particularly in medical applications. In particular, partial areas of the mouth or areas within the mouth can be imaged.

[0016] A surgical microscope includes a stereo camera system having a first image capture device and another image capture device. These devices can each be designed to generate two-dimensional images. In this case, images with a predetermined number of picture elements and, therefore, a predetermined resolution can be generated. For example, the image sensors of the image capture devices can be CMOS sensors or CCD sensors. Of course, other sensor types can also be used. As described above, the surgical microscope can include two optically independent beam paths, wherein the first image capture device is arranged and / or designed to generate an image based on the beam guided in the first beam path. The other image capture device can be arranged and / or designed to generate another image based on the beam guided in the other beam path. In particular, the images can be generated simultaneously. Furthermore, the images generated by the first and other image capture devices and subsequently used to generate a three-dimensional image can be referred to as corresponding images. This description also extends to surgical microscopes that, in addition to or as an alternative to the stereo camera system, use another optical capture system to generate three-dimensional images, particularly to provide depth information. Such an optical capture system has been described in the introduction above.

[0017] Furthermore, the surgical microscope may include at least one optical element for beam guidance and / or beam shaping, which may in particular be in the form of a lens element, wherein the at least one optical element may be used, for example, to generate a magnified image. The optical properties of the surgical microscope (e.g., magnification, focus, zoom, exposure time, and capture area size) may be adjustable.

[0018] The stereo camera system can be a calibrated stereo camera system. In particular, the aforementioned intrinsic and extrinsic parameters of the stereo camera system can be predetermined, in particular by calibration methods known to those skilled in the art. Preferably, the aforementioned parameters are determined for all operating states or predetermined operating states of the surgical microscope, wherein the operating state is characterized by set (adjustable) parameters of the surgical microscope (e.g., zoom, focus, capture area).

[0019] The surgical microscope may further include at least one eyepiece through which a user can gaze or gaze into the eyepiece in order to visually capture images generated by the surgical microscope. In particular, the user can also capture the examination area in three dimensions through the eyepiece. The surgical microscope may include at least one objective or an objective system, wherein the objective system includes at least one optical element for beam guidance and / or beam shaping. The eyepiece may be optically connected to the objective or may be already optically connected to the objective.

[0020] A surgical microscope can be part of a microscope system, which can also include not only the surgical microscope but also a stand for holding the surgical microscope. In this context, the stand can be designed to allow the surgical microscope to be moved in space, in particular with at least one degree of freedom, preferably six degrees of freedom, where the degrees of freedom can be translational or rotational. The degrees of freedom in this context can relate to a reference coordinate system. The vertical axis (z-axis) of this reference coordinate system can be oriented parallel to and opposite to gravity. In this context, the longitudinal axis (x-axis) and transverse axis (y-axis) of the reference coordinate system can span a plane oriented perpendicular to the vertical axis. Furthermore, the longitudinal axis and transverse axis can also be oriented orthogonal to each other. Furthermore, the stand can include at least one drive device, such as a servo motor, for moving the surgical microscope. The stand can also include devices for transmitting force / torque, such as gears and / or coupling units. Thus, the surgical microscope can be mounted or held in a movable manner. This allows, among other things, the user to modify the posture, i.e., position and / or orientation, of the surgical microscope, for example, to change the viewing angle on the examination area or to view a different examination area.

[0021] The surgical microscope may in particular be a dental surgical microscope which is designed for generating images in dental applications.

[0022] A partial section of a row of teeth can in particular comprise at least one tooth or a part of a tooth. A tooth can also be a denture within the meaning of the present invention.

[0023] According to the present invention, the proposed method comprises the following steps:

[0024] In a first step, corresponding imaged mirror images are detected in an image generated by a first image capture device of the stereo camera system and in an image generated by another image capture device of the stereo camera system. The mirror images are provided by mirror elements arranged in a capture area of the stereo camera system.

[0025] Therefore, in particular, before detecting the imaged mirror image, the aforementioned mirror element can be arranged in the capture area of the stereo camera system, wherein the mirror image of at least a partial section of the tooth row can be imaged by the first image capture device and the further image capture device. Furthermore, before the detection, images, in particular corresponding images, can be generated by the image capture devices and subsequently used to determine the three-dimensional image. This will be explained in detail below.

[0026] In particular, the mirror element can be a dental mirror or a part thereof. In particular, the mirror element can include a mirror surface that reflects radiation or take the form of a mirror surface that reflects radiation. An image of the mirror surface generated by the image capture device, i.e., an imaged mirror image, is generated by capturing the reflected radiation. The mirror image generated / provided by the mirror element is thus perceived by means of capturing the reflected radiation. The capture by the image capture device results in the generation of an imaged mirror image. However, in addition to the imaged mirror image, the image generated by the image capture device can also include other areas that are not imaged by the mirror image. In other words, the mirror image can be imaged in a partial area of the image generated by the image capture device. In the imaged mirror image, at least a partial section of the row of teeth is imaged. The mirror element can also include a frame section surrounding the mirror surface. The mirror element can also include a handle section so that a user can position the mirror element in space. The mirror element is preferably a mirror element with a non-curved mirror surface. Preferably, the mirror surface is a circular surface. However, it is also conceivable to use a polygonal mirror surface.

[0027] In a second step, the attitude of the mirror element, in particular the attitude of the mirror surface, is determined. The attitude can include a translation component and a rotation component. For example, the position of a reference point of the mirror element (e.g. the center of the mirror surface) and the orientation of the mirror element (e.g. the orientation of the normal to the mirror surface) can be determined as the attitude of the mirror element. It goes without saying that the positions of multiple reference points of the mirror element or the orientation of multiple partial segments can also be determined as attitudes, in particular in the case of curved mirror surfaces. An exemplary method for determining the attitude is explained in detail below. The attitude can be determined in a reference coordinate system. For example, this can be the reference coordinate system of a stereo camera system or a surgical microscope, or the reference coordinate system explained previously.

[0028] In the third step, a three-dimensional image is determined based on at least the imaged mirror image detected in the (corresponding) images generated by the two image capture devices and the pose of the mirror element. For example, a stereo reconstruction method can be used for this purpose, with the imaged mirror image forming the input image for the method. Such methods are known to those skilled in the art. In particular, such methods can determine corresponding image elements in the two input images. For example, feature matching methods can be used to determine such corresponding pixels or groups of pixels. Corresponding methods and features are known to those skilled in the art. An exemplary feature is the so-called SIFT feature, i.e., a scale-invariant feature transform feature. However, it goes without saying that other methods can also be used for this determination, such as variational methods or AI-based methods. Three-dimensional coordinates can then be determined for the object points or object segments imaged in the corresponding image element or group of image elements in the reference coordinate system explained above. This can also be referred to as reconstruction, wherein the corresponding reconstruction method is performed based on the pose of the mirror element. In particular, at least one method step of the reconstruction method can be performed based on the pose. In particular, the pose can be represented by at least one parameter, with at least one method step being performed based on this parameter or taking this parameter into account during implementation. Preferably, a stereo triangulation reconstruction method is performed to determine the three-dimensional image. Stereo triangulation reconstruction methods are known to those skilled in the art. In this case, the projection matrix used during reconstruction can be determined based on the attitude of the mirror element and (known) reflection laws, which projection matrix describes the perspective transformation of the three-dimensional object coordinates in the reference coordinate system into the two-dimensional image coordinates. In other words, the attitude of the mirror element affects the projection matrices of the two image capture devices and therefore also the stereo triangulation reconstruction performed based on or depending on these projection matrices. For example, so-called homogeneous solution methods or so-called inhomogeneous solution methods can be applied to the determination of the three-dimensional coordinates. In particular, a correction method for compensating for or eliminating nonlinear distortions in the image can be performed before the three-dimensional image is determined.

[0029] The proposed method advantageously allows a simple, accurate and patient-friendly generation of three-dimensional images, in particular intraoral scans, since, in contrast to the previously explained existing methods, it is generally only necessary to arrange a mirror element of small dimensions in the mouth in order to capture a partial section of a row of teeth and image it in three dimensions.

[0030] The proposed method is particularly used to generate a three-dimensional image of the back side of a row of teeth and / or the occlusal or chewing surfaces of the row of teeth. The back side of the row of teeth may particularly refer to the side of the row of teeth facing the inside of the mouth. A three-dimensional image of the front side of a row of teeth or a partial section of the row of teeth can be determined without the above-mentioned first and second steps. In particular, the three-dimensional image can therefore be determined based on a corresponding image that has already been generated by an image capture device, wherein in particular known methods for stereo reconstruction can be used. The image capture device for generating the image can be arranged outside the oral cavity, i.e. extraorally. Therefore, the method can also be referred to as extraoral scanning.

[0031] For example, a 3D image can be generated in the form of a CAD dataset, for example in STL format. Such a 3D image can then be visualized, for example, by outputting it to a display device. The 3D image can also be used in further processes, such as CAD / CAM processes, for example to create a dental impression.

[0032] In another embodiment, the three-dimensional image is additionally determined based on at least one optical property of the mirror element. In this context, the at least one optical property can be predetermined. Alternatively, the at least one optical property can also be determined in another step of the proposed method, particularly in an image-based manner, i.e., by evaluating at least one image of the mirror element. In particular, the optical property of the mirror element can be a magnification or reduction property. It goes without saying that other optical properties of the mirror element that influence the mirror image can also be considered. For example, the optical property can be represented by the interpreted projection matrix. This advantageously results in high accuracy of the generated three-dimensional image.

[0033] Alternatively or cumulatively, the three-dimensional image is further determined based on at least one imaging property of the surgical microscope. In particular, the imaging property can be a set magnification (zoom), a set focus, or any other imaging property that influences the imaged image. This imaging property can also be represented by the interpreted projection matrix. This also advantageously allows for the generation of highly accurate three-dimensional images.

[0034] In another embodiment, a (corresponding) image of a virtual image capture device is determined based at least on the pose of the mirror element, wherein at least one corresponding segment of the row of teeth reflected in the catadioptric system is imaged in the image of the virtual image capture device. Furthermore, a three-dimensional image is determined based on the image of the virtual image capture device (in particular, the corresponding segment in the corresponding image).

[0035] A catadioptric system represents a relay optical system that includes at least a mirror element of an image capture device and an optical element, such as an objective lens. In particular, the catadioptric system can include the optical elements of an objective lens of a surgical microscope. The beam path through the catadioptric system can be determined based on the optical properties of the optical elements in the catadioptric system (these properties are known or determinable in advance), the attitude of the mirror element, and known optical laws.

[0036] A virtual image capture device is a mathematical or physical model of an image capture device that can, in particular, be evaluated with the aid of a computer. Based on the model, a virtual image generated by the virtual image capture device can be generated or calculated, in particular by computer-implemented calculation of picture elements. This virtual image depends, in particular, on the parameters of the (modeled) image capture device and the pose of the (modeled) image capture device. These parameters of the virtual image capture device, in particular extrinsic and / or intrinsic parameters, can depend on the optical properties of the mirror element. If, for example, the mirror surface is not curved and has no magnifying properties, the intrinsic parameters of the virtual image capture device can be equal to the intrinsic parameters of the modeled image capture device.

[0037] In particular, the pose of the virtual image capture device can be determined based on the pose of the mirror element, so that the virtual image of the virtual image capture device in this pose images a non-reflective segment of the row of teeth, which is reflected by the catadioptric system and therefore also by the mirror element. The latter represents the corresponding segment. In addition to the pose of the mirror element, the generation of this virtual image also depends on (further) properties of the catadioptric system, such as the set zoom of the objective lens.

[0038] A three-dimensional image can then be determined based on the virtual image (particularly the virtual image of the corresponding segment) using methods known to those skilled in the art. An exemplary method has been explained above. In this method, in particular, the properties of the catadioptric system, and therefore also the properties of the mirror element's posture, can be taken into account. In other words, the reflected image can be transformed into a non-reflected image, and then a three-dimensional image can be generated based on the non-reflected image. This advantageously results in an accurate and computationally simple determination of the three-dimensional image, which can be generated with particularly high precision.

[0039] In another embodiment, the gesture is determined by evaluating at least one property of the imaged mirror image or the imaged mirror element (or a segment thereof). The at least one property can be determined in an image-based manner, in particular by evaluating an image generated by a corresponding image capture device. In particular, the imaged mirror surface or the imaged mirror element can be identified in such an image, for example, using object recognition methods known to those skilled in the art. For example, the object recognition method can be a segmentation method. Thus, for example, the imaged mirror surface, the imaged frame segment, or the imaged handle segment can be identified in an image-based manner. For example, a segment of the mirror element (e.g., a frame segment) can be formed from a material with predetermined optical properties (e.g., a matte material), in particular to allow reliable detection of this segment in the image. Alternatively, detection can also be achieved by the user selecting an image region, for example, via a suitable input device, in which the imaged mirror image or segment to be detected is imaged.

[0040] The properties of the imaged mirror or the imaged mirror element can be geometric properties of the imaged mirror, such as dimensional properties, such as dimensional variables. The dimensional variables can be width, height, diameter, or any other dimensional variables. In addition, the properties can be shape properties, such as geometric shapes, such as circular shapes, elliptical shapes, rectangular shapes, or any other geometric shapes. In particular, a shape factor representing the relationship between the imaged shape and the actual shape can be determined, wherein the pose is determined based on the shape factor.

[0041] As mentioned above, the pose of the mirror element may affect the imaging of the image capture device. Therefore, the pose may also affect how the actual properties of the mirror image or the mirror element are mapped onto the properties of the imaged mirror image or the mirror element. If the relationship between the actual properties and the properties of the imaged mirror image can be described by a transformation matrix that depends on the pose, the pose can be determined based on the actual properties and the properties of the imaged mirror image or the imaged mirror element. The actual properties can be known, for example from a model of the mirror element (in particular a CAD model), or can be determined.

[0042] If the mirror element or a portion thereof (particularly the mirror surface) is circular and the imaged mirror image is elliptical, the pose can be determined based on the properties of the ellipse (e.g., the orientation and length of the ellipse axes) and the previously known properties of the circular mirror element, such that the previously known properties are transformed into the properties of the imaged mirror image. If a polygonal mirror element is used, particularly an equilateral polygonal mirror element, at least a portion of the pose can be determined by the ratio of the edge lengths in the image and the relative positions of the edges in the image.

[0043] Additionally, the property may be the pose of the imaged mirror image or the imaged mirror element or a portion thereof in the image coordinate system. For example, the position may be determined as the position of a reference point (e.g., a geometric center). For example, the orientation may be determined as the orientation of an axis of a reference segment. For example, if the mirror element includes a handle segment, the handle segment may be identified in the image and its position and / or orientation may be determined. For example, the orientation of the longitudinal axis of the handle segment may be determined.

[0044] If the pose is determined by evaluating at least one property of the imaged mirror image or the imaged mirror element, this advantageously results in a simple determination of the pose, since any image generated can be evaluated for the purpose of determining the pose.

[0045] Alternatively, the pose can be determined based on markers. To this end, the mirror element can include or take the form of at least one marker element for determining the pose of the mirror element. Of course, the mirror element can also include or take the form of multiple markers, wherein the pose of the mirror element can be determined based on the previously known relative positions and / or sizes of these markers.

[0046] The marker element can be an active marker element or preferably a passive marker element. It can be designed to be captured by a capture device. In particular, the capture device can be an image capture device. Therefore, in this case, the marker element can be an optically captureable marker element. For example, it is conceivable that the optically captureable marker includes a predetermined pattern that allows the posture of the marker and therefore the posture of the mirror element to be determined. For example, such an optically captureable pattern can take the form of a QR code. In addition, such an optically captureable marker can be a reflective marker element, wherein these are designed, for example, to reflect radiation from a predetermined wavelength range (for example, an infrared wavelength range). The image capture device for optically capturing the marker element can be an image capture device of a stereo camera system or a different image capture device. If the mirror element includes a plurality of marker elements, the posture of the mirror element can also be determined based on the relative positions of the imaged marker elements in the image. In addition, the posture of the mirror element can be determined at least in part by stereoscopic determination of the posture of at least the marker elements.

[0047] The image capture device and the marking element can be used to perform, in particular, so-called monoscopic pose determination. In this case, the pose can be determined by evaluating two-dimensional images, in particular, exactly one two-dimensional image from exactly one image capture device. In particular, the intensity values of the pixels of the two-dimensional image can be evaluated to determine the position. Such methods for image-based position detection using exactly one image capture device and / or based on exactly one two-dimensional image are known to those skilled in the art. However, if a stereo camera system is used, the pose can also be determined by evaluating the corresponding images of the image capture devices.

[0048] In particular, the pose can thus be determined by an optical tracking method, wherein in particular an image capture device is used to determine the pose. Such optical tracking can be marker-based tracking, wherein specific visually or optically captivating marker elements, such as QR codes or optical patterns of different designs, are used to determine the pose.

[0049] Alternatively, in particular in the case of the above-described determination of the pose by evaluation of at least one property of the imaged mirror image or the imaged mirror element, markerless tracking methods can also be applied, in which features are captured and used for determining the pose in these methods.

[0050] However, as an alternative to optically captivating marking elements, it is also possible to use marking elements that can be captured by other means to determine the pose of the mirror element, for example magnetically, capacitively, inductively or in a radio-based manner. For example, the marking element can be designed as an RFID tag.

[0051] The mirror element may further comprise a posture sensor, such as an initialization sensor or a GNSS sensor, wherein the posture is determined based on an output signal of such a sensor. In such an embodiment, the surgical microscope may comprise a receiver device for the output signal generated by the posture sensor, or may be connected to such a receiver device.

[0052] It goes without saying that a hybrid method can also be used to determine the pose, wherein such a hybrid method combines at least two of the above-explained methods for determining the pose.

[0053] In the case of marker-based pose determination, there is advantageously a very accurate determination of the pose, which in turn leads to the generation of an accurate three-dimensional image.

[0054] The marking element can also be identifiable, particularly bidirectionally identifiable. For example, the pattern of an optically identifiable marking can encode the marking's identity. Thus, the marking element or mirror element can be identified by capturing the marking element. Thus, a determinable identity can be assigned to the properties of the mirror element, particularly the optical properties explained above. This assignment, along with the identity and properties, can be stored in a retrievable or readable manner, for example, in a memory device. This advantageously allows for simple determination of the optical properties of the mirror element.

[0055] For the purpose of marker-based pose determination, in another embodiment, at least one marker element is imaged by at least one image capture device of a stereo camera system or by another image capture device. At least one marker element is arranged on or formed by a mirror element. The pose is then determined based on at least one property of the imaged marker element. This has already been explained above. The other image capture device can, in particular, be a tracking camera or an environment camera of a microscope system, which takes a different form than the image capture device of the stereo camera system. This tracking or environment camera can be used in particular for marker-based tracking of another instrument. In both cases, this advantageously results in the simplest possible integration of optical pose determination when using a surgical microscope or a microscope system with a surgical microscope.

[0056] In a further embodiment, the focus position of the surgical microscope is set based on the posture of the mirror element. In particular, this allows the focus position to be set at a point on the mirror surface or at a point no more than a predetermined distance from the mirror surface. In particular, the predetermined distance may depend on the depth of field of the surgical microscope, and in particular, may be smaller than the depth of field range. In this case, the depth of field is known or can be determined in advance. This enables the mirror element to achieve higher imaging quality, which in turn advantageously increases the accuracy of the generated three-dimensional image.

[0057] In particular, this also allows easier and more reliable detection of imaged mirror images in the images of the image capture device.

[0058] In another embodiment, the radiation captured to generate the images of the stereo camera system is filtered. In a preferred embodiment, the filtering is polarization filtering. However, it goes without saying that other radiation filters can also be used. Advantageously, this can suppress unwanted reflections from the tooth surface in the image, thereby improving the accuracy of the generated three-dimensional image. In this case, polarization filtering allows for maximum or complete suppression of reflections.

[0059] In another embodiment, the filter element is arranged in the illumination beam path and / or the imaging beam path of the surgical microscope. In particular, a corresponding filter element can be arranged in each imaging beam path. Both cases result in excellent structural integration of the filter element in the surgical microscope or microscope system, which allows for the generation of very accurate three-dimensional images.

[0060] In another alternative or cumulative embodiment, a filter element is arranged on the mirror element. For example, the filter element can be arranged on the mirror surface of the mirror element. Advantageously, since the mirror element provides the required filter properties, no additional filter element needs to be integrated into the surgical microscope or microscope system to generate high-precision three-dimensional images.

[0061] In another embodiment, at least a partial section of a row of teeth is illuminated by radiation having predetermined radiation properties. For example, such radiation properties may be predetermined wavelength(s), predetermined intensity, or, in a preferred embodiment, predetermined polarization properties or other properties of the radiation used for illumination purposes. Advantageously, this may also reduce reflections from the tooth surface, which in turn has a favorable effect on the accuracy of the generated three-dimensional image.

[0062] In another embodiment, images generated by a stereo camera system are filtered, wherein a three-dimensional image is determined based at least on the filtered images. In particular, filtering can be performed to reduce unwanted reflections in the image. However, filtering can also be used to improve image quality, thereby advantageously increasing the accuracy of the three-dimensional image. An exemplary filtering method for reflection suppression is the so-called tone mapping method.

[0063] For example, the teeth may be temporarily stained during image capture. Color filtering may then be performed, where, for example, color components in the image that differ from the color of the stain are reduced.

[0064] In another embodiment, at least one quality metric of the 3D image is determined. Furthermore, if the quality metric is less than a predetermined threshold, user information is generated. In this case, the quality metric is selected so that it is proportional to the quality of the 3D image. The user information can be output to the user via an output device, such as an optical or acoustic output device. This can be part of a surgical microscope or microscope system.

[0065] For example, it may be determined whether the point density in a predetermined region of the generated three-dimensional image is less than a predetermined threshold. If this is the case, user information may be generated because it may be desirable to perform a more accurate reconstruction with a higher density in at least this portion of the region. In particular, the determined quality metric (e.g., point density) may be generated as part of the user information.

[0066] Furthermore, if the quality measure is determined in a subregion-specific manner, information about the subregion, in particular its pose, can be generated as part of the user information.

[0067] This advantageously results in ensuring a high precision of the generated three-dimensional image, since the user information is generated in the case of a possible undesirably low quality, and the method is, for example, performed again, in particular for partial regions in which an unacceptably low quality measure has been determined.

[0068] A system for generating a three-dimensional image of at least a partial section of a row of teeth is also proposed, wherein the system comprises a stereo camera system and at least one evaluation device. The stereo camera system comprises a first image capture device and a further image capture device. The system is configured to perform a method according to one of the embodiments described in the present disclosure, in particular the following steps:

[0069] a) detecting a mirror image in an image generated by a first image capture device and in an image generated by a further image capture device, wherein the mirror image is provided by a mirror element which is arranged in a capture area of the stereo camera system and reflects at least a partial section of a row of teeth,

[0070] b) determining the attitude of the mirror element,

[0071] c) Determining a three-dimensional image based at least on the imaged mirror image and the pose of the mirror element.

[0072] The evaluation device may take the form of or include a computing device. The computing device may in turn include or take the form of a microcontroller or an integrated circuit. In this case, the evaluation device may perform at least one of steps a), b), and c), but preferably performs all of these steps.

[0073] The system can be part of a surgical microscope or microscope system, wherein the surgical microscope or microscope system can include a stereo camera system and an evaluation device. Furthermore, the system can include a capture device for capturing a marking element. Furthermore, the system can include a filter element for filtering radiation used to generate an image of the stereo camera system. Furthermore, the system can include an illumination device for illuminating a partial area with predetermined radiation properties. Furthermore, the system can include an output device for user information.

[0074] The system advantageously enables the implementation of a method according to one of the embodiments described in the present disclosure, as well as the advantages that have likewise been described.

[0075] In another embodiment, the system comprises a mirror element to be arranged in a capture area of the stereo camera system.

[0076] A computer program product is also proposed, comprising a computer program, wherein the computer program comprises software means for performing, when the computer program is executed by or in a computer or an automated system, one, several or all steps of the method according to one of the embodiments described in the present disclosure, in particular steps from the set comprising the first step, the second step and the third step. In other words, the method may be a computer-implemented method.

[0077] A mirror element for generating a three-dimensional image of at least a partial section of a row of teeth is also proposed. According to the invention, the mirror element includes or forms at least one marking element for determining the pose of the mirror element. Alternatively or in addition, the mirror element includes or forms at least one filter element for filtering reflected radiation. This advantage and corresponding advantages have already been explained above. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The present invention will be explained in detail based on exemplary embodiments. In the accompanying drawings:

[0079] Figure 1 shows a schematic flow chart of the method according to the present invention,

[0080] Figure 2 shows a schematic flow chart of a method according to the invention in another embodiment,

[0081] Figure 3 shows a schematic block diagram of a system according to the present invention,

[0082] Figure 4a shows the mirror element in a first attitude,

[0083] Figure 4b Shown in another posture Figure 4a The mirror element depicted in

[0084] Figure 4c Shown in another posture Figure 4a The mirror element depicted in

[0085] Figure 4d Shown in another posture Figure 4a The mirror element depicted in

[0086] Figure 5 shows a schematic illustration of a mirror element according to the invention,

[0087] Figure 6 shows a schematic block diagram of a virtual image capture device,

[0088] Figure 7a A schematic diagram showing a stereoscopic capture of a row of teeth without a mirror element, and

[0089] Figure 7b Schematic diagram showing a stereoscopic capture of a row of teeth with mirror elements.

[0090] The same reference numerals below denote elements having the same or similar technical features. DETAILED DESCRIPTION

[0091] Figure 1A schematic flow chart of the method according to the invention for generating a row of teeth Z (see FIG. Figure 3 ). Prior to the first step S1 of the method, a mirror element 3 is arranged in the capture area 4 of the stereo camera system 1 so that a mirror image of at least a partial section of the row of teeth Z can be imaged by the first image capture device 5a and the other image capture device 5b of the stereo camera system 1 (arrangement step SA). Following this arrangement, the first image capture device 5a and the other image capture device 5b each generate corresponding images I5a, I5b, which may be referred to as corresponding images (image generation step SB). These images are generated from different positions and / or with different orientations. Furthermore, these images may be generated simultaneously or with a predetermined maximum time offset. In the first step S1 of the method, the imaged mirror image S5a is then detected in the image I5a generated by the first image capture device 5a, for example, using an object recognition method. In addition to the partial area imaged by the mirror element 3, the image I5a generated by the first image capture device 5a may also include further partial areas, such as those that image other partial sections of the row of teeth Z, particularly those that are not reflected by the mirror element 3. In the image I5b generated by the further image capture device 5b, the imaged mirror image S5b is also detected accordingly. The imaged mirror images S5a, S5b thus detected form input variables for determining the three-dimensional image A. In the second step S2 of the method, the posture P, i.e., the position and / or orientation, of the mirror element 3 is determined in a reference coordinate system. The reference coordinate system can be the coordinate system of the surgical microscope 2 used as a reference or the coordinate system of the stereo camera system 1 used as a reference. It goes without saying that other reference coordinate systems are also conceivable. In addition to the imaged mirror images S5a, S5b, the posture P forms another input variable for determining the three-dimensional image A.

[0092] In a third step S3 , a three-dimensional image A is then determined based on at least the imaged mirror images S5 a , S5 b and the pose P of the mirror element 3 , for example by or using stereo reconstruction. This has already been explained above.

[0093] In this context, it should be mentioned that Figure 1 The order of the first step S1 and the second step S2 depicted in FIG is not mandatory. In particular, the pose P can be determined simultaneously with or before the detection of the imaged mirror images S5a, S5b.

[0094] It is also possible to additionally determine the three-dimensional image A based on at least one optical property of the mirror element 3. This optical property then forms another input variable for the third step S3. In this context, the optical property can be predetermined. In this case, in particular, the mirror element can be identified, wherein at least one optical property can be assigned to a preferably doubly unique identity of the mirror element 3. Based on this assignment, the optical property can then be determined using the determined identity of the mirror element 3, for example, retrieved from a database, which can be stored in a storage device and indicates the assignment of identities to the at least one optical property. Figure 1 This identification step, not shown in the figure, can be performed before the third step S3. Preferably, the mirror element can be image-based identified, for which purpose at least one of the images I5a, I5b generated by imaging the mirror element 3 is evaluated. For example, without being mandatory, identification can be performed simultaneously with the determination of the posture in the second step S2. Identification can be achieved by evaluating at least one property of the imaged mirror element or using a marker-based approach. This will be explained in detail below in conjunction with the determination of the posture P.

[0095] Alternatively or cumulatively, before third step S3, imaging properties of surgical microscope 2, such as the currently set zoom, can also be determined. This imaging property of surgical microscope 2 can then form a further input variable for third step S3. Thus, three-dimensional image A can be determined additionally based on at least one optical property of mirror element 3 and / or based on at least one imaging property of surgical microscope 2.

[0096] The determination of the pose P of the mirror element 3 in the second step S2 can be carried out in an image-based manner, in particular by evaluating at least one property of the imaged mirror image S5a, S5b or the imaged mirror element 3. The property can be a dimensional property. The property can also be a shape property. These have been explained above. In particular, the property can be determined in the images S5a, S5b and compared with the mirror image or the mirror element 3 in a reference position (see, for example Figure 4a ), in particular with a mathematically determinable image of the mirror image or mirror element 3 in this reference position. The pose P of the mirror element 3 can then be determined based on the deviation between the actual properties in the image and the thus determined previously known properties. For example, a transformation can be determined for transforming the image of the mirror image or mirror element in the reference position into the actual image, said transformation containing information about the current pose P of the mirror element 3.

[0097] Alternatively, the determination of the pose P can be implemented in a marker-based manner. To this end, the Figure 5In the exemplary embodiment of FIG, a marking element is depicted as an optically captivating marking element 6. Such a marking element 6 can be an active marking element, i.e. a marking element which generates a captivating signal under energy consumption, or a passive marking element which can be captured without consuming energy. Figure 5 The optically capturable marker element 6 depicted in the figure, in the form of a barcode or optical pattern, is an example of a passive marker element. However, it is also self-evident that the optically capturable marker can also be an active marker, which, for example, generates an optically capturable signal with the expenditure of energy. However, as an alternative to the optically capturable marker element 6, a marker element that is capturable in another form, such as a magnetically capturable marker element, can also be used. In this case, the marker element can be arranged in or on the mirror element 3, wherein the mirror element's posture P can then be determined based on the captured marker element.

[0098] If at least one marking element is an optically capturable marking element 6, e.g. Figure 5 , then, in order to determine the pose P, at least one marker element can be imaged by at least one image capture device 5a, 5b of the stereo camera system 1 or by another image capture device (not shown), and the pose P can then be determined based on at least one property of the imaged marker element. In this case, the pose P can only be determined after the corresponding images I5a, I5b have been captured.

[0099] It is also conceivable to set the focus position of surgical microscope 2 based on the posture P of mirror element 3. In this case, images I5a, I5b that are evaluated for determining three-dimensional image A can be generated after determining posture P. If posture P is determined in an image-based manner, images for determining posture P can be generated before posture P is determined, wherein the focus position is then set based on posture P, and images I5a, I5b are subsequently generated for detecting imaged mirror images S5a, S5b.

[0100] Figure 2 FIG. 1 shows a schematic flow chart of a method according to another embodiment of the present invention. Figure 1 In contrast to the embodiment shown, in a further image generation step SBV, images I5a, I5b (i.e. corresponding images) are additionally generated from the front side 7 of the row of teeth Z, wherein in a reconstruction step SRV a three-dimensional partial image A1 of the front side is generated based on these images I5a, I5b. Subsequently, Figure 1The method shown in FIG. 1 illustrates a method in which the resulting image A is a partial image A2 of the back surface 8 of a row of teeth Z and the chewing surfaces 9 of the teeth in the row Z. In a fusion step FS, the partial images A1 and A2 are fused / combined to form a composite image A of the row of teeth Z. To this end, corresponding points in the three-dimensional partial images A1 and A2 can be detected in order to fuse the partial images A1 and A2. For this purpose, it may be necessary to scale the structures imaged in at least one of the partial images A1 and A2, particularly those in the partial image A2 of the back surface 8. This scaling can be achieved, in particular, based on the distance between the mirror element 13 and the reflective section of the row of teeth Z. This distance can be determined, in particular based on the pose P of the mirror element 13. The distance can also be determined based on different focus positions of the stereo camera system 1, as will be explained in detail below. The partial images A1, A2 and the composite image A can preferably be provided in an STL data format, which advantageously allows for use in further processes, in particular CAD / CAM processes. The composite three-dimensional image A or the partial images A1 and A2 can also be displayed to a user via a suitable display device. Information, such as color information, may be superimposed on the displayed image.

[0101] Figure 3 A schematic block diagram of a system according to the invention for generating a three-dimensional image A of at least a partial section of a row of teeth Z is shown, wherein the system comprises a stereo camera system 1 and at least one evaluation device 10. The system is configured to perform at least Figure 1 and Figure 2 It goes without saying that the system can also be configured to perform steps S1, S2, S3. Figure 2 In this case, the steps SBV, SRV, FS or at least parts thereof can be executed by the evaluation device 10.

[0102] Figure 3 The capture area EB of the image capture devices 5a, 5b and the optically separated beam paths 11a, 11b of the surgical microscope 2 are schematically depicted. The illumination device of the surgical microscope 2, which is capable of illuminating the row of teeth Z, is not depicted. In this case, the illumination device can generate radiation with predetermined radiation properties (in particular, predetermined polarization properties). The radiation reflected by the row of teeth Z reaches the image sensors of the image capture devices 5a, 5b via the beam paths 11a, 11b, thereby generating an image I5a, I5b of the row of teeth Z. This image can be evaluated by the evaluation device 10. Also depicted is a mirror element 3, which likewise reflects a beam from the row of teeth Z, in particular its rear face 8, wherein this reflected radiation also reaches the image sensor via the beam paths 11a, 11b and is imaged there as a mirror image. This image can then be detected by the evaluation device 10 as the mirror image.

[0103] The radiation captured to generate the images I5a, I5b of the stereo camera system 1 can be filtered. This can be achieved, for example, by filter elements arranged in each beam path 11a, 11b. Furthermore, a filter element can be arranged in the illumination beam path of an illumination device (not depicted) of the surgical microscope 1. Furthermore, a filter element can be arranged on / at the mirror element 3. In particular, such a filter element can be a polarization filter element. It is also possible for the evaluation device 10 to filter the images I5a, I5b generated by the image capture devices 5a, 5b, for example to suppress reflections.

[0104] Figure 4a The image of the mirror element 3 in the reference pose is shown. The mirror element 3 comprises a handle section 12 and a circular mirror section 13, which in turn comprises a mirror surface 14. For example, the center of this mirror surface 14 is the reference point P3 of the mirror element 3. A coordinate system is depicted which is stationary relative to the mirror and has a longitudinal axis x3, a transverse axis y3 and a vertical axis z3 (see Figure 4b ).

[0105] Figure 4b The image shows the mirror element 3 in a posture P, which is the posture P when the mirror element 3 moves from Figure 4a The reference position shown is formed when rotating about the longitudinal axis x3a. Obviously, in this case, Figure 4a The circular mirror surface 14 depicted in FIG is imaged as an ellipse. Depending on the orientation and length of the major and minor axes of this ellipse (which can be detected, for example, by an object recognition method), the rotation angle of the mirror element 3 about the longitudinal axis x3a can then be determined, wherein the angle x3a can then again be determined. Figure 4b The current pose P of the imaging mirror element 3 is shown.

[0106] In a similar way, Figure 4c and Figure 4d Shown with Figure 4a The reference position shown is compared to the reference position around the transverse axis y3 ( Figure 4c ) or around the vertical axis z3( Figure 4d ) Rotating imaging mirror element 3. For example, it is possible to rotate the imaging mirror element 3 based on the longitudinal axis x3 ( Figure 4d ) and / or the orientation and length of the axis of the elliptical image of the mirror surface 14 to determine the corresponding rotation angle.

[0107] from Figures 4a to 4d It can be seen that there can be a shape-based determination of the pose P of the mirror element 3 , wherein shape properties of the imaged mirror element 3 can be determined and the pose P can then be determined based on these properties.

[0108] It is also clear that the center of the mirror surface 14 is detectable. If, in addition to the point of reflection on the mirror surface 14 (e.g., the center), the focus is also directed to the non-reflective edge of the mirror surface 14, the distance of the mirror surface 14 (in particular, the reflection point) from the row of teeth Z can be determined by the difference in the focus position.

[0109] In particular, the difference between the focal position when focusing the stereo camera system 1 or surgical microscope 2 on a point on a non-reflective edge (e.g., a point on the frame segment 13) and the focal position when focusing on a point on an object reflected at the mirror surface 14 (e.g., a point reflected at the center of the mirror surface 14) can be determined. This difference in focal position can represent the distance between the mirror element 13 and the object (in this case, a point on the row of teeth Z), and the distance can therefore be determined based on this difference. Furthermore, the distance can also be determined based on the pose P of the mirror element 13. This distance information can be used for scaling within the described stereo reconstruction, in particular to match the magnification when reconstructing reflective segments (e.g., the back side 8 of the row of teeth Z) to the magnification when reconstructing non-reflective segments (e.g., the front side 7 of the row of teeth Z), i.e., to perform scaling.

[0110] Figure 5 A schematic diagram of a mirror element 3 according to the invention is shown. The latter comprises or forms a marking element 6 on the handle section 12, the marking element 6 being in the form of an optically capturable barcode. The mirror element 3 also comprises a further optically capturable marking element 6 on the frame section 13 of the mirror surface 14, which is in the form of a barcode. These marking elements can be captured in the image of the mirror element 3, wherein these marking elements in particular enable the mirror element 3 to be identified and the pose P of the mirror element 3 to be determined. In particular, it is possible to Figure 5 Each marker element 6 is detected in the case of the mirror element 3 depicted in FIG. 1 , wherein the pose P can then be determined from the relative arrangement of the marker elements in the image.

[0111] Figure 6 A stereo camera system 1 is shown (see Figure 3 ) is a schematic diagram of an image capture device 5 and a mirror element 3, which is arranged in a capture area EB of the image capture device 5. Also depicted are object points OP to be imaged, for example points on the surface of a row of teeth Z (see Figure 3 ). The normal n to the mirror surface 14 of the mirror element 3 is also depicted.

[0112] Also depicted is a virtual image capture device 15. The (virtual) image of this virtual image capture device 15 can be determined by evaluating a mathematical or physical model. In particular, the model is determined by generating a virtual image that images a section of the row of teeth Z in a non-reflective manner, that is, specifically, an object point OP corresponding to a reflective section in a catadioptric system, while taking into account the properties of the catadioptric system. A three-dimensional image A can then be determined based on the virtual image using methods known to those skilled in the art, for example, by means of or using stereo reconstruction. This has already been explained above.

[0113] Figure 7a A schematic diagram of the stereoscopic capture of a row of teeth Z by two image capture devices 5a, 5b of a stereo camera system 1 without a mirror element 3 is shown. The capture of the front side 7 of the row of teeth Z is depicted, for example as in a further image generation step SBV for reconstructing a three-dimensional image A of the front side 7 (see Figure 2 ) implemented in .

[0114] Figure 7b A schematic diagram of the stereoscopic capture of a row of teeth Z by two image capture devices 5a, 5b of a stereo camera system 1 with a mirror element 3 is shown. The mirror element 3 is shown, which is arranged inside the mouth and provides a back side 8 of the row of teeth Z (see Figure 3 ), which is then imaged by the image capture devices 5a, 5b. The three-dimensional image A of the back side 8 is then reconstructed based on the corresponding imaged mirrors S5a, S5b.

[0115] Furthermore, preoperative data may also be used together with the images generated by the image capture devices 5 a , 5 b in order to generate a three-dimensional image A.

[0116] In an alternative embodiment, and similar to the stereoscopic detection of the treatment area, depth information can also be optically captured by a further capture system used in the surgical microscope in order to generate a three-dimensional image of at least a partial section of the row of teeth. For this purpose, the further detection system can be used to generate a replacement image as a substitute for the image generated by the first image capture device and the image generated by the further image capture device, and in this replacement image, a mirror image provided by a mirror element arranged in the capture area of the surgical microscope, in particular, in the capture area of the capture system, can be detected. As explained, the pose of the mirror element and the three-dimensional image can then be determined based at least on the imaged mirror image and the pose of the mirror element. Thus, in particular, optical depth information of a partial section of the row of teeth can be made available to the surgical microscope, and in particular, to the capture system, and embedded in a suitable coordinate system.

[0117] Reference Signs List

[0118] 1 Stereo Camera System

[0119] 2. Surgical microscope

[0120] 3 mirror elements

[0121] 4 Capture Area

[0122] 5.5a,5b Image capture device

[0123] 6 Optically captureable marking elements

[0124] 7 Positive

[0125] 8 Back

[0126] 9 chewing surfaces

[0127] 10 Evaluation device

[0128] 11a, 11b beam paths

[0129] 12 handle sections

[0130] 13 frame sections

[0131] 14 mirror surfaces

[0132] 15Virtual Image Capture Device

[0133] SA Layout Steps

[0134] SB image generation steps

[0135] S1 First step

[0136] S2 second step

[0137] S3 Step 3

[0138] SBV image generation steps

[0139] SRV Reconstruction Steps

[0140] EB capture area

[0141] I5a, I5b images

[0142] Mirror image of S5a and S5b

[0143] P-stance

[0144] A1, A2, A images

[0145] OP object point

Claims

1. A method for generating a three-dimensional image (A, A2) of at least a partial section of a row of teeth (Z) using a stereo camera system (1) of a surgical microscope (2), wherein the stereo camera system (1) comprises a first image capture device (5a) and a further image capture device (5b), wherein: a. detecting corresponding imaged mirror images (S5a, S5b) in the image (I5a) generated by the first image capture device (5a) and the image (I5b) generated by the further image capture device (5b), the imaged mirror images being provided by a mirror element (3) arranged in the capture region (4) of the stereo camera system (1), so that a mirror image of at least one partial section of the row of teeth (Z) can be imaged by the first image capture device (5a) and the further image capture device (5b), b. determining the pose (P) of the mirror element (3), c. Determining the three-dimensional image (A, A2) based on at least the imaged mirror images (S5a, S5b) and the pose (P) of the mirror element (3).

2. The method according to claim 1, characterized in that The three-dimensional image (A, A2) is also determined as a function of at least one optical property of the mirror element (3) and / or at least one imaging property of the surgical microscope (2).

3. The method according to any one of the preceding claims, characterized in that An image of a virtual image capture device is determined based at least on the posture (P) of the mirror element (3), wherein at least one corresponding segment of the row of teeth (Z) reflected in the catadioptric system is imaged in the image of the virtual image capture device, wherein the three-dimensional image (A, A2) is determined based at least on the image of the virtual image capture device.

4. The method according to any one of the preceding claims, characterized in that The pose (P) is determined by evaluating at least one property of the imaged mirror image or of the imaged mirror element (3) or in a marker-based manner.

5. The method according to claim 4, characterized in that For the purpose of determining the pose (P) based on the marker, at least one marker element (3) is imaged by at least one image capture device (5a, 5b) of the stereo camera system (1) or by another image capture device, wherein the at least one marker element (6) is arranged on the mirror element (3) or is formed by the mirror element (3), wherein the pose (P) is determined based on at least one property of the imaged marker element (6).

6. The method according to any one of the preceding claims, characterized in that The focus position of the surgical microscope (2) is set based on the posture (P) of the mirror element (3).

7. The method according to any one of the preceding claims, characterized in that Radiation captured for generating images (I5a, I5b) of the stereo camera system (1) is filtered.

8. The method according to claim 7, characterized in that The filtering is polarization filtering.

9. The method according to claim 7 or 8, characterized in that The filter element is arranged in the illumination beam path and / or in the imaging beam path (11a, 11b) and / or on the mirror element (3).

10. The method according to any one of the preceding claims, characterized in that At least a partial section of the row of teeth (Z) is irradiated with radiation having predetermined radiation properties.

11. The method according to claim 10, characterized in that Radiation having predetermined polarization properties is generated.

12. The method according to any one of the preceding claims, characterized in that The images (I5a, I5b) generated by the stereo camera system are filtered, wherein the three-dimensional image (A, A2) is determined based on at least the filtered images.

13. The method according to any one of the preceding claims, characterized in that At least one quality metric of the three-dimensional image (A, A2) is determined, wherein user information is generated if the quality metric is less than a predetermined threshold.

14. A system for generating a three-dimensional image (A, A2) of at least one partial section of a row of teeth (Z), comprising a stereo camera system (1) comprising a first image capture device (5a) and at least one further image capture device (5a), and at least one evaluation device (10). It is characterized in that The system is configured to perform the following steps: a. detecting imaged mirror images (S5a, S5b) in the image (I5a) generated by the first image capture device (5a) and in the image (I5b) generated by the further image capture device (5b), wherein the mirror images are generated by a mirror element (3) which is arranged in the capture area (4) of the stereo camera system (1) and reflects at least a partial section of the row of teeth (Z), b. determining the pose (P) of the mirror element (3), c. Determining the three-dimensional image (A, A2) based at least on the imaged mirror images (S5a, S5b) and the pose (P) of the mirror element (3).

15. The system according to claim 14, wherein: The system comprises a mirror element (3).

16. A computer program product comprising a computer program, wherein The computer program comprises software means for performing one, several or all of steps a) to c) of the method according to any one of claims 1 to 14 when the computer program is executed by or on a computer or an automation system.

17. A mirror element for generating a three-dimensional image (A, A2) of at least a partial section of a row of teeth (Z), characterized in that The mirror element (3) comprises or takes the form of at least one marking element (6) for determining the pose (P) of the mirror element (3) and / or at least one filter element for filtering the reflected radiation.

Images