Method and device for adjusting an indoor camera for outside-in tracking of smart glasses

Abstract

The invention relates to a method for providing a camera pose indication that specifies a camera pose of an adjustable indoor camera, comprising the following steps: - Capturing a camera image from the interior camera; - Providing a reference camera image for a given reference camera pose; - Performing an image comparison between the reference camera image and the captured camera image to identify feature points that are assigned to identical elements and to determine 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image; - Determining a camera pose change depending on the 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image - Applying the camera pose change to the reference camera pose to obtain the camera pose information.

Description

[0001] The invention relates to the use of data glasses in vehicles, and in particular to the contact-analog display of display objects. The invention further relates to measures for providing a glasses pose by an external system for performing sensor fusion in the data glasses.

[0002] Data glasses, also called head-mounted displays, are known that, with the aid of a display device, can display an image on one or two display surfaces in the wearer's field of vision. The display surfaces usually correspond to reflective surfaces that direct images into the wearer's eyes. The viewing openings of the data glasses are transparent, allowing the real environment to be perceived through the data glasses in the usual way. The display surfaces are located in the viewing openings, allowing information to be displayed, such as text, symbols, graphics, video displays, and the like, to be displayed overlaid on the perception of the environment.

[0003] The information is usually presented to the wearer of the data glasses in a contact-analog manner, i.e., it is presented in such a way that it is superimposed as object information on a specific assigned object in the real environment or is oriented toward it, or that the object information to be displayed is displayed in a specific orientation of the data glasses or their wearer. Furthermore, the contact-analog object information can be presented in such a way that it appears perspectively correct with respect to the object in the real environment, i.e., the illusion is created that the object in the real environment has actually been supplemented with the additional feature of the visual object information.

[0004] In order to display the object information on the display surfaces of the smart glasses in a contact-analog manner, it is necessary to know the position of the object in the environment, the position of the user's eyes, and their gaze direction. When wearing the smart glasses, the user's gaze direction is permanently assigned to the glasses' pose, i.e., the 3D position and the 3D orientation of the smart glasses relative to a reference coordinate system, such as the vehicle coordinate system (vehicle-fixed) or the environment coordinate system (world-fixed).

[0005] Particularly when using smart glasses in a vehicle, a pose recognition unit can be provided in the smart glasses to determine the glasses pose information based on the glasses pose of the smart glasses. The pose recognition unit typically comprises a glasses movement sensor and a computing device, e.g., in the form of a microprocessor. Using glasses movement information acquired at high frequency, particularly in the form of 3D acceleration information and / or 3D angular velocity information, the current glasses pose of the smart glasses in the vehicle interior can be tracked by temporally integrating the relative glasses movement information in order to update the glasses pose information. The current glasses pose is first updated with respect to the world environment and then extrapolated.While a simple temporal integration is sufficient for updating the absolute orientation of the data glasses, a double temporal integration of the translational 3D acceleration information is required for updating the absolute position of the data glasses.

[0006] When determining the absolute eyeglass pose information by considering the integration of the eyeglass movement information, an integration error typically occurs. Without correction, this error leads to an increasing discrepancy between the absolute eyeglass pose information provided in the smart glasses and the actual current eyeglass pose. Due to the double integration, the integration error in determining the absolute position of the smart glasses is significant.

[0007] To determine the current glasses pose information with respect to a vehicle coordinate system, movement information of the data glasses recorded in the vehicle can be transmitted to the data glasses so that an absolute glasses pose information relative to the vehicle (with respect to a vehicle coordinate system) can be determined.

[0008] The current glasses pose can be determined by an external pose recognition unit (outside-in tracking method), in which a camera inside the vehicle captures the head of the data glasses wearer. By evaluating the camera image using vision tracking methods, either the head pose is determined and the absolute glasses pose value is derived from this, or the absolute glasses pose value is determined directly. In these so-called outside-in tracking systems, a vehicle-specific absolute glasses pose value is determined, i.e., an absolute glasses pose value related to a vehicle-fixed coordinate system.

[0009] The absolute eyeglass pose information can be transmitted periodically (with a timestamp) to the data glasses, where the updated absolute eyeglass pose information determined by the integration method can be corrected in the data glasses by sensor fusion in order to compensate for the integration error.

[0010] For outside-in tracking of data glasses, it can be provided that a corresponding interior camera, which can be used to determine an absolute glasses pose fixed to the vehicle, is arranged in an interior mirror unit. Depending on the driver's size and seating position, the interior mirror unit is usually adjusted at the start of the journey so that the driver sees the desired section of the rear vehicle surroundings from his or her perspective via the mirror surface. Since the interior camera is arranged in the interior mirror unit, the interior camera located therein receives a new orientation, i.e. a new camera pose, with each readjustment of the interior mirror unit. However, to determine the absolute glasses pose, precise knowledge of the orientation or even the pose of the interior camera relative to a vehicle coordinate system is necessary.

[0011] It is therefore an object of the present invention to provide a method for determining an accurate camera pose specification of an interior camera relative to the vehicle coordinate system.

[0012] This object is achieved by the method for determining the absolute camera pose information of an interior camera for determining an absolute glasses pose in a vehicle according to claim 1 and by the device and a vehicle system according to the independent claims.

[0013] Further embodiments are specified in the dependent claims.

[0014] According to a first aspect, a method is provided for providing a camera pose indication that indicates a camera pose of an adjustable interior camera, comprising the following steps: - Capturing a camera image from the interior camera; - Providing a reference camera image for a given reference camera pose; - performing an image comparison between the reference camera image and the captured camera image to identify feature point pairs with feature points associated with identical elements and to determine 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image in the captured camera image; - Determining a camera pose change, in particular in the form of an essential matrix, depending on the 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image; and - Apply the camera pose change to the reference camera pose to obtain the camera pose information. - Apply the camera pose change to the reference camera pose to obtain the camera pose information.

[0015] For the contact-analog display of display objects in augmented reality data glasses, knowledge of the absolute pose of the glasses relative to a reference system is necessary. If data glasses are used in a vehicle, the reference system corresponds to a vehicle reference system for displaying contact-analog display objects relative to vehicle-fixed elements. This means that display objects are displayed superimposed on a specific position or a specific element belonging to the vehicle.

[0016] To use smart glasses for the contact-analog display of display objects, knowledge of the exact current pose of the smart glasses is necessary. The current pose corresponds to an absolute pose value in the smart glasses, which should specify the actual pose as accurately as possible and is used for the contact-analog display of display objects.

[0017] The glasses pose comprises a spatial absolute position (3D position) as well as the 3D orientation in three spatial directions. For pose determination, smart glasses typically incorporate a glasses motion sensor in the form of an IMU (Inertia Measurement Unit). This sensor incorporates acceleration sensors and gyroscopes to determine translational accelerations, angular accelerations, and angular velocities as glasses motion information. Starting from an absolute glasses pose specification at a specific time, these can be used through single and / or double temporal integration to update the glasses pose specification over time by accumulating incremental changes in the position and orientation of the smart glasses.

[0018] To determine the change in the orientation of the smart glasses, the angular velocities of the smart glasses are simply integrated over time. This allows the incremental change in orientation to be determined to extrapolate the absolute orientation of the glasses. Compensation with the vehicle motion detected in the vehicle is generally not necessary, as the vehicle's orientation changes only at very low frequencies.

[0019] However, determining the change in the position of the data glasses as part of the glasses pose is technically very challenging, since updating the current absolute position of the current glasses pose information requires considering the difference between the acceleration information from the glasses' movement sensors and the translational acceleration information acquired by a vehicle-mounted sensor. Furthermore, kinematic terms in the moving vehicle must be taken into account, including, for example, centripetal acceleration, Coriolis acceleration, and the like. These terms are not directly measurable and must be estimated by a tracking filter.To obtain the current change in position, the differential acceleration, including kinematic terms taken into account, must first be simply integrated over time to determine the speed of the data glasses, and then the speed must be integrated again.

[0020] Due to integration, the drift in the updating of the absolute eyeglass pose information increases quadratically over time, which can lead to large errors in pose determination even after short periods of time. Therefore, regular correction of the eyeglass pose information determined by integration is necessary to compensate for this drift in position determination and to be able to provide the current eyeglass position with sufficient accuracy.

[0021] The regular transmission of an absolute glasses pose specification from the vehicle system external to the glasses (relative to a vehicle coordinate system) is therefore necessary for providing the current glasses pose specification in the data glasses. This requires that the interior camera, which records the camera image with which a pair of data glasses in the vehicle interior can be identified using a vision tracking method and whose glasses pose can be determined, must have precise knowledge of its position and orientation in the vehicle coordinate system. A camera image captured by the interior camera therefore shows a section of the vehicle interior that is well-defined in terms of orientation and position, i.e. the camera pose, and the position of the data glasses, which is detected in the camera image, can thus be precisely assigned to a glasses position and orientation relative to a vehicle coordinate system.

[0022] One problem is that the orientation of the interior mirror can be changed by the user at any time and thus the camera pose of the interior camera can be indeterminate.

[0023] To determine the camera pose, an initial calibration is provided, e.g., during commissioning, which defines a reference camera image for a known reference camera pose. The initial calibration can be predefined and, in particular, derived from an actual acquisition of a camera image with a known camera pose.

[0024] Areas can be masked out of the reference camera image so that the comparison is made only with those areas of the interior view that are not masked. In particular, the masked areas can correspond to those areas of the interior view that represent moving elements in the vehicle interior and / or that may be occupied by vehicle occupants. By appropriately masking the reference camera image, areas can be hidden where elements are dynamically adjustable during vehicle operation, or areas where vehicle occupants may obscure visible elements.

[0025] To determine the camera pose, a recorded camera image can be compared with the reference camera image to locate feature points corresponding to identical elements in the vehicle interior. These feature points can be identified by 2D image coordinates in the reference camera image and the captured camera image, so that corresponding features in the reference camera image and the captured camera image can be determined using a feature matching method.

[0026] By comparing the reference camera image with the captured camera image, identical feature points can be found that do not need to have been previously defined as reference points. The feature points are obtained by separately evaluating the captured camera image and the reference camera image to obtain a set of feature points each. Feature matching can be used to bring the feature points into the best possible match, e.g., using algorithms such as SIFT, SURF, ORB, AKAZE, etc. Using the feature point pairs, an essential matrix can be determined, e.g., using RANSAC. The pose of the captured camera image relative to the reference camera image is then determined from the feature point pairs, essential matrix, and camera matrix.

[0027] The essential matrix describes the epipolar geometry between the reference camera pose and the camera pose to be determined, where the camera's intrinsic parameters are known. The essential matrix contains only the rotation matrix and the translation matrix.

[0028] The fundamental matrix describes the epipolar geometry between the reference camera pose and the camera pose to be determined. Unlike the essential matrix, the fundamental matrix considers both intrinsic and extrinsic camera parameters.

[0029] One can switch from the fundamental matrix to the essential matrix if the intrinsic parameters of the camera are known.

[0030] The essential matrix is ​​used to estimate the camera pose information of the camera with respect to a reference camera pose (pose change) and the intrinsic parameters of the camera are known.

[0031] Using a well-known algorithm such as SIFT, SURF, ORB, AKAZE, etc., a pose change in the camera pose information of the indoor camera relative to the reference camera pose can be determined from the 2D image coordinates of the feature points in the reference camera image and the 2D image coordinates of the feature points in the acquired camera image. This pose change can be applied to the reference camera pose through a simple coordinate transformation to obtain the current camera pose information.

[0032] The reference camera image can correspond to a camera image recorded during an initial calibration at a reference camera pose. Alternatively, the reference camera image can also be a camera image simulated at a given reference camera pose, e.g., using Unity, which was created based on CAD data of the vehicle interior at a given camera pose of the interior camera.

[0033] In particular, areas in the reference camera image where feature points are identified can be masked. The masked areas correspond to those areas of the interior view that represent moving elements in the vehicle interior and / or that may be obscured by vehicle occupants.

[0034] Thus, the interior view can be masked to exclude potentially moving elements and areas where vehicle occupants may be located from the image comparison. Thus, it may be sufficient to render the interior view with only the fixed elements of the vehicle interior that are visible regardless of seat occupancy.

[0035] According to a further aspect, a device, in particular a control unit, is provided for providing a camera pose indication which indicates a camera pose of an adjustable interior camera, in particular on an adjustable interior mirror, wherein the device is designed to: - Capturing a camera image from the interior camera; - Providing a reference camera image for a given reference camera pose; - performing an image comparison between the reference camera image and the captured camera image to identify feature point pairs with feature points associated with identical elements and to determine 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image in the captured camera image; - Determining a camera pose change, in particular in the form of an essential matrix, depending on the 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image; and - Apply the camera pose change to the reference camera pose to obtain the camera pose information.

[0036] According to a further aspect, an arrangement for operating a vehicle system is provided, comprising: - an adjustable interior mirror with an interior camera mounted on / in it; - the above control unit; - data glasses designed to display at least one display object depending on a glasses pose specification; - wherein the control unit is further configured to determine the absolute glasses pose information of the data glasses by a vision tracking method in the camera image depending on the camera pose information and to transmit the absolute glasses pose information to the data glasses.

[0037] Embodiments are explained in more detail below with reference to the attached drawings. They show: Fig. 1 a schematic plan view of a vehicle system with a display system; Fig. 2 a schematic representation of a display system with data glasses in a motor vehicle; Fig. 3 shows a flowchart illustrating a method for determining a camera pose information of an indoor camera.

[0038] Fig. 1 schematically shows a top view of a vehicle system with a vehicle 1 in which a driver or a vehicle occupant N wears data glasses 3. The data glasses 3 are connected via a communication link 4, either wired or wirelessly, to a pose recognition system 2 fixed to the vehicle.

[0039] The communication connection 4 is designed as a data transmission channel, e.g., in the form of a wireless communication connection or a wired communication connection. The communication connection 4 is capable of transmitting any type of data and information between the assistance system 2 and the data glasses 3, for example, based on packet-based data transmission. The communication connection 4 can be based, for example, on Wi-Fi, Bluetooth, Bluetooth Low Energy, or a comparable standardized radio protocol.

[0040] Fig. Figure 2 shows a schematic representation of the vehicle system.

[0041] The assistance system 2 can be part of a vehicle assistance system and, in particular, can be provided in a fixed location in the vehicle 1. The assistance system 2 can be equipped with a communication unit 23 that enables the communication connection 4 between the data glasses 3 and the assistance system 2.

[0042] The assistance system 2 can also be connected to the camera system 21, which has an interior camera 22 directed into the interior of the vehicle. The interior camera 22 is attached to a movable interior mirror, so that when the interior mirror is adjusted or adjusted, e.g., by a driver, the camera pose of the interior camera is adjusted. The camera system 21 can capture the vehicle occupants N as a camera image. The interior camera 22 can comprise, for example, an RGB, IR, fisheye camera, a dynamic vision sensor, and the like.

[0043] The assistance system 2 can have a control unit 24 for evaluating the camera image using a pattern recognition method and determining an absolute eyeglass pose specification of the one or more data glasses 3 in the vehicle. The absolute eyeglass pose specification specifies a eyeglass pose relative to a vehicle coordinate system, i.e., an absolute eyeglass position and an absolute eyeglass orientation (preferably in all spatial directions).

[0044] Furthermore, the assistance system 2 includes a vehicle motion sensor (IMU sensor) 25, which can be implemented, for example, in the form of a 6-DOF inertial sensor. This provides motion information about the movement of the vehicle 1 in the form of translational accelerations or angular accelerations or angular velocities.

[0045] The data glasses 3 comprise two transparent viewing panels 32, which are enclosed in a frame 31 in a conventional manner. The frame 31 is provided, for example, with temples 33, so that the data glasses 3 can be worn on a user's head.

[0046] One or both viewing panes 32 (lenses) are further provided with a transparent display surface 35, through which a suitable device, such as a display device 36 arranged on the frame 31, can project a display image for displaying virtual display objects into the eye of the wearer of the data glasses 3. The display device 36 can comprise a microprocessor or a comparable computing unit and a display unit, such as a projection device or the like. The display unit can be configured to direct the electronically generated display image onto the display surface 35 and project / display it there.

[0047] Due to the transparent design of the display surface 35, the electronically generated image can be superimposed on the real environment perceivable through the display surface 35. Using the display device 36, a virtual display object, such as text, a symbol, video information, a graphic, or the like, can be displayed on one or both display surfaces 35.

[0048] The data glasses 3 can be worn on the user's head like a typical visual aid, with the frame 31 of the data glasses 3 resting on the user's nose and the temples 33 resting laterally against the user's head. The user's straight-ahead gaze direction is then determined by the transparent display surfaces 35 of the viewing panels 32, so that the user's gaze direction, which is determined by an eye position and an optical viewing axis (eye axis), has a fixed reference to the orientation of the data glasses 3. This reference depends individually on the wearer of the data glasses 3 and is specified by calibration information.

[0049] To display display objects, corresponding object information in the form of object data is transmitted from the assistance system 2 to the data glasses 3 or is already provided in the data glasses 3. The object data specifies the type of display object, such as a text object, an icon, or other designation of a display area, the viewing angle range(s) in which the display object is to be displayed on the display surface 35, and the object position in the environment of the data glasses 3. The object position can be specified with respect to a world-fixed environmental coordinate system or a vehicle-fixed vehicle coordinate system.

[0050] A goggle movement sensor system 38 (IMU sensor system, inertial sensor system) can be provided, which is designed, for example, in the form of a 6-DOF inertial sensor (acceleration sensor and gyroscope). This provides goggle movement information about a movement of the data glasses 3 in the form of translational accelerations and angular accelerations or angular velocities, which can be converted, in particular, by a respective (including double) integration into a change in position and orientation, i.e., a differential goggle pose specification, so that a speciation of a goggle pose can be updated at high frequency by applying a time integration method.

[0051] The position and orientation changes (differential glasses pose) determined by the glasses movement sensor system 38 can be used in a conventional manner to determine a world-fixed current glasses pose specification for a current glasses pose of the data glasses 3. To determine a vehicle-fixed glasses pose specification, the glasses movement information must be adjusted depending on the vehicle movement information so that only the movement of the data glasses 3 in the vehicle can be evaluated. The difference in movement between the movement of the data glasses and the movement of the vehicle is determined and evaluated to determine the current glasses pose specification.

[0052] With the help of a control unit 37, for example, object information can be received from the assistance system 2 via a communication device 39 or provided and processed in some other way, so that it is displayed in a contact-analog manner in the respective viewing angle range into which the user of the data glasses 3 is looking and in which surrounding objects can be perceived, depending on the current glasses pose specification with respect to the surrounding coordinate system. This means that the display object specified by the object information is displayed on the display surface 35 if its surrounding position is within the viewing angle range.

[0053] The user N of the data glasses 3 is a passenger in the vehicle 5 and the glasses pose of the data glasses 3 can change due to head movements and movement of the vehicle. For the contact-analogous representation of a display object in relation to an environmental position, i.e. the corresponding object information is provided with an environmental position, on the display surface of the data glasses 3, a current glasses pose specification related to the environmental coordinate system U must be present in the data glasses 3. Accordingly, for the contact-analogous representation of a display object in relation to a vehicle-fixed position, i.e. the corresponding object information is provided with a position relative to the vehicle (vehicle-fixed), on the display surface of the data glasses 3, an absolute glasses pose specification related to the vehicle coordinate system F must be present in the data glasses 3.

[0054] In the display system, a method is carried out as shown, for example, in the flow chart of Fig. 3 is described in more detail.

[0055] In step S1, a camera image is captured with the interior camera 22.

[0056] The camera image shows a section of the vehicle interior including a vehicle occupant who may be wearing data glasses 3.

[0057] Since the camera pose of the interior camera 22 may have changed due to adjustment of the interior mirror, a camera pose specification is determined accordingly in step S2 by comparing a reference camera image, which is initially provided with a known reference camera pose, with the captured camera image. An initial reference camera pose is previously known for the reference camera image.

[0058] To compare the reference camera image with the captured camera image, feature points are first determined in the reference camera image and the captured camera image. Subsequent feature matching determines corresponding feature points, resulting in pairs of feature points. The 2D image coordinates in the reference camera image and the 2D image coordinates in the captured camera image are known for the feature points.

[0059] By appropriately masking the initial reference camera image, areas of the reference camera image can be masked out for comparison in which vehicle occupants may be located, such as above the vehicle seats, or in which elements of the vehicle interior that are movable are located, such as backrests of vehicle seats and the like.

[0060] Feature matching results in pairs of feature points. The shift in the 2D image coordinates between the reference camera image and the acquired camera image enables the determination of an essential matrix in step S3 based on known parameter estimation algorithms, such as RANSAC. From the essential matrix and the reference camera pose (specified, for example, by a camera matrix), the camera pose change can be determined using matrix multiplication.

[0061] Subsequently, in step S4, the reference camera pose is applied to the determined essential matrix to obtain the current camera pose information.

[0062] The position and orientation are determined by scaling and matrix multiplication in a known manner.

[0063] Using the camera pose information and performing a vision tracking procedure with the captured camera image, the absolute glasses pose information of the data glasses 3 relative to the vehicle coordinate system can be determined in step S5 using simple vector mathematics.

[0064] This absolute eyeglass pose information can now be transmitted to the data glasses 3 in step S6, so that in step S7, using a data fusion of the absolute eyeglass pose information updated by integration and the transmitted absolute eyeglass pose information can be provided in the data glasses 3. This can be used for the contact-analogous, i.e., position-accurate representation of display objects.

[0065] The procedure described above can be carried out regularly, ie with the recording of each new camera image, or only after an adjustment of the interior mirror has been detected by other means. List of reference symbols 1 vehicle 2 Assistance system 3 data glasses 4 Communication connection 21 Camera system 22 Camera 23 Communication unit 24 Control unit 25 Vehicle motion sensors 32 viewing windows 31 frames 33 temples 35 display area 36 Display device 38 Glasses movement sensors 37 Control unit N users

Claims

[1] A method for providing a camera pose indication indicating a camera pose of an adjustable interior camera (22), comprising the following steps: - capturing (S1) a camera image of the interior camera (22); - Providing a reference camera image for a given reference camera pose; - performing (S2) an image comparison between the reference camera image and the captured camera image to identify feature point pairs with feature points assigned to identical elements and to determine 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image in the captured camera image; - determining (S3) a camera pose change, in particular in the form of an essential matrix, depending on the 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image; and - Apply the camera pose change to the reference camera pose to obtain the camera pose information. [2] Method according to claim 1, comprising the further steps: - determining (S5) an absolute glasses pose of data glasses (3) by a vision tracking method in the camera image depending on the camera pose information; - Transmitting (S6) the absolute glasses pose to the data glasses (3). [3] Method according to claim 1 or 2, wherein areas are masked out in the reference camera image so that the comparison is made only with those areas of the interior view which are not masked. [4] Method according to claim 3, wherein the masked areas correspond to those areas of the interior view which represent movable elements in the vehicle interior and / or which may be occupied by vehicle occupants. [5] Method according to one of claims 1 to 4, wherein the feature point pairs are determined using feature matching methods, in particular SIFT, SURF, ORB or AKAZE, wherein the camera pose change is determined from the feature point pairs, each of which assigns a 2D image coordinate in the reference camera image to a 2D image coordinate in the captured camera image, using a parameter estimation method, in particular a RANSAC algorithm. [6] Method according to one of claims 1 to 5, wherein the provision of a reference camera image for a predetermined reference camera pose is carried out by specifying the reference camera pose and generating the reference camera image by a simulation based on CAD data of the vehicle interior, in particular with a graphics engine, such as Unity, depending on the reference camera pose. [7] Device, in particular a control unit (24), for providing a camera pose indication which indicates a camera pose of an adjustable interior camera (22), in particular on an adjustable interior mirror, wherein the device is designed to: - capturing a camera image from the interior camera (22); - Providing a reference camera image for a given reference camera pose; - performing an image comparison between the reference camera image and the captured camera image to identify feature point pairs with feature points associated with identical elements and to determine 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image in the captured camera image; - Determining a camera pose change, in particular in the form of an essential matrix, depending on the 2D image coordinates in the reference camera image and 2D image coordinates in the captured camera image; and - Apply the camera pose change to the reference camera pose to obtain the camera pose information. [8] Arrangement for operating a vehicle system, comprising: - an adjustable interior mirror with an interior camera (22) arranged thereon / in it; - a control unit (24) according to claim 7; - data glasses (3) which are designed to display at least one display object depending on a glasses pose specification; - wherein the control unit (24) is further designed to determine the absolute glasses pose information of the data glasses (3) by means of a vision tracking method in the camera image as a function of the camera pose information and to transmit the absolute glasses pose information to the data glasses (3).

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