Methods for Validating Indirect Observation Systems

Abstract

A method for verifying an indirect observation system is provided, which provides at least one image acquisition unit, which has at least one image sensor, at least one image processing unit, at least one reproduction unit and at least one reference sensor located at a defined position of a vehicle, so that the reference sensor is located in a recording portion of the image acquisition unit and is depicted on the image sensor. The reference sensor is defined at a reference sensor target position on the image sensor. With the method, image data of at least one recording portion of the vehicle's surroundings are acquired on the image sensor and reproduced on the reproduction unit. Then, a reference sensor current position of the reference sensor is determined on the image sensor and the reference sensor current position is compared with the reference sensor target position to determine whether the reference sensor current position is equal to the reference sensor target position.

Description

Technical Field

[0001] The invention relates to a method for checking an indirect observation system (in particular a recording part of an image acquisition unit or a reading part of an image sensor of an image acquisition unit) of a vehicle (in particular a passenger car or a commercial vehicle), an indirect observation system configured to perform the method, and a vehicle comprising the indirect observation system. Background Art

[0002] In motor vehicles, the law requires that during driving operations, the driver must be able to see the so-called field of view around the vehicle. The field of view that must be visible depends on the type of motor vehicle, such as a motorcycle, a motor vehicle for transporting passengers, a motor vehicle for transporting goods, etc. The visibility of the field of view must be provided by an indirect viewing device, and by using the indirect viewing device, the field of view must always be visible to the driver sitting in the driver's seat. Depending on the type of vehicle, in particular, depending on which areas around the vehicle the driver can directly observe, different legal provisions require that certain fields of view are permanently and reliably visible by using indirect viewing devices. In Europe and some countries outside Europe, the field of view that the driver must always reliably see is defined in UN / ECE Regulation No. 46. Other relevant specifications and regulations include, for example, ISO 5721, ISO5006, ISO 16505, ISO 14401 and EU 167 / 2013, respectively. In addition to the legally prescribed field of view, the indirect viewing device usually also makes other areas around the vehicle (the so-called field of view) visible. The field of view area may include the legally prescribed field of view.

[0003] Typically, one or more mirrors can be used to observe the field of view. However, mirrors also have some disadvantages. For example, the mirror only shows the driver objects on the same side of the mirror as the driver. Any object behind the mirror can only be displayed with difficulty through the mirror. In addition, unless the mirror is very close to the driver, the area displayed to the driver by the mirror made only of flat glass is very small. If they are convex, image distortion will occur. Large vehicles usually have six or more mirrors, which are installed around the outside of the vehicle, most of which are convex and will produce distortion, which makes it difficult for the driver to pay attention to all relevant mirrors at the same time. However, despite having so many mirrors, there are usually still blind spots in the field of view area around these vehicles, that is, areas without field of view.

[0004] In recent years, it has become increasingly common to consider the use of camera systems as indirect observation devices as a supplement or alternative to mirrors of indirect observation devices. In such camera systems, images are continuously acquired and are detected and processed respectively and, if so, stored. The (video) data acquired by the image acquisition unit are transmitted to a display device located in the cab, for example by using a supply unit and optionally after further processing. The display device depicts a view of the field of view or multiple fields of view as required by the relevant legislation and optionally depicts supplementary information on the area surrounding the vehicle, such as potential risks of collision, distance to other objects, etc., so that the field of view is permanently visible to the driver. At the same time, the observation system offers excellent night vision, more flexible arrangement options and the opportunity to observe a larger field of view with reduced distortion.

[0005] Here, permanently visible means that the view in the field of view is depicted in an uninterrupted manner in time, i.e., without interruptions by alternately showing and hiding the field of view or parts thereof or by covering other representations so that the field of view cannot be seen completely. Thus, the corresponding one or more fields of view are shown continuously and in real time on the display device. This applies at least to the fields of view that have to be permanently visible for all vehicle conditions, wherein the ignition switch is turned on and / or preferably are coupled to a sensor that receives a corresponding signal, such as a door open signal or an ignition switch signal.

[0006] A camera system is used as an indirect observation device, and a camera and an image acquisition unit are respectively mounted on the vehicle body. The camera and the image acquisition unit respectively capture at least one lateral portion of the vehicle environment, which corresponds to the portion that the driver sees in the rearview mirror or the front mirror on the common side. In particular, for commercial vehicles, it is desirable to make the flat and horizontal portions of the road surface have a specific width, which extends from a defined distance behind the viewpoint of the vehicle driver to the horizon that can be seen on the driver's side and the passenger side, respectively. By using a common mirror at a certain distance behind the driver's viewpoint, the width of the stripe is equivalent to the field of view of the wide-angle mirror (for example, the field of view IV defined in ECE R46), and at a shorter distance behind the driver's viewpoint, it is equivalent to the field of view of the main mirror (for example, the field of view II defined in ECE R46), and its predefined visible width (i.e., the extension length in the lateral direction of the vehicle) is smaller than the field of view width of the wide-angle mirror. The area of ​​the front mirror corresponds to the field of view VI of UN / ECE R46, for example.

[0007] In order to reliably capture or record the field of view of a common wide-angle mirror, respectively, with a camera and an image acquisition unit, respectively, the camera and the image acquisition unit are usually mounted at a distance to the body of the vehicle, such as at the distal end of a multi-part, articulated camera arm, which is characterized in that its longitudinal extension is significantly longer than its transverse extension. Furthermore, it may be advantageous to mount such a camera arm at a position on the body that is different from the usual position for mounting a common mirror, with regard to capturing the required field of view. Thus, it may be the case that the camera is mounted at a position on the body that cannot be seen by the driver during driving.

[0008] However, in particular with such a multi-component camera arm, it may happen that the camera (e.g. due to a collision of the camera arm with an object in the vehicle's surroundings or external impacts (displacement of the camera arm due to interference by third parties)) is positioned relative to the vehicle in such a way that one or more fixed defined recording sections (e.g. the fields of view II and IV or one or more individually defined fields of view required by the above-mentioned law) are no longer displayed or are no longer displayed in full. If this involves only slight deviations between the recording section to be displayed and the recording section actually displayed, it may happen that the driver (especially if he is not familiar with the vehicle) is not aware of this deviation. As a result, he may become aware of a possible dangerous situation too late or not at all, as a result of the deviation between the recording section to be displayed and the recording section actually displayed, which is not recorded or is not recorded sufficiently, with the result that the risk of a collision between the vehicle and other traffic participants or objects in the vehicle's surroundings increases.

[0009] In practice, the field of view of a camera can only be verified and adjusted with very extensive test setups. In this regard, reference targets are placed in vehicle test benches between which the vehicle is positioned so that the reference targets have a fixed geometric reference to the vehicle. Errors in the position of the vehicle and tolerances of the vehicle (e.g. component tolerances, different vehicle assemblies, measurements with and without driver, etc.) make precise verification difficult and extensive. In particular, for small vehicle manufacturers, complex verification processes are hardly feasible, as this would incur high costs and increase the time period. In addition, for the driver, for example, if such deviations occur during operation of the vehicle, this is not something that can be achieved on his own or requires additional effort. If the image acquisition unit is repaired or replaced, the same disadvantages also occur during the repair and replacement process, respectively.

[0010] A method for determining the installation position and / or orientation of multiple cameras of a camera system of a vehicle is known from WO 2017 / 174250 A1. A mirror replacement system for a vehicle is known from EP 2 692 584 A1. A calibration device and a method for determining calibration data are known from DE 10 2018 111 776 A1. Summary of the invention

[0011] In view of this, the object of the present invention is to provide a method for verifying an indirect observation system of a vehicle, which method is capable of identifying deviations between a fixed defined area to be displayed on a reproduction unit and an area actually displayed on the reproduction unit. In addition, the object of the present invention is also to provide a corresponding observation system.

[0012] The object is achieved by the following solution: A method for inspecting an indirect observation system of a vehicle, in particular a passenger car or a commercial vehicle, the method having the following characteristics: providing at least one image acquisition unit, which has at least one image sensor and is configured to acquire image data of at least one recording portion to the side and rear of the vehicle, providing at least one image processing unit, which is configured to process the image data acquired by the image acquisition unit, providing at least one reproduction unit, which is configured to reproduce the image data processed by the image processing unit, providing at least one reference sensor at a defined position of the vehicle, so that the reference sensor is located in the recording portion of the image acquisition unit and is displayed on the image sensor, wherein the reference sensor is defined as a reference sensor target position on the image sensor, acquiring image data of at least one recording portion around the vehicle on the image sensor including the reference sensor, reproducing at least one image reading portion read from the image data of the image sensor on the reproduction unit, determining a reference sensor current position of the reference sensor on the image sensor, and comparing the reference sensor current position with the reference sensor target position. to determine whether the current position of the reference sensor is equal to the reference sensor target position; an observation system for a vehicle (especially a commercial vehicle), which can perform the method and has the following characteristics: at least one image acquisition unit, which includes an image sensor and is configured to acquire image data of at least one recording portion of the side and rear of the vehicle, at least one image processing unit, which is used to process the image data acquired by the image acquisition unit; at least one reproduction unit, which is configured to reproduce the image data processed by the image processing unit, at least one reference sensor, which is configured to be attachable to a defined position on the vehicle, and in a state where the indirect observation system is installed on the vehicle, the reference sensor is located in the recording portion of the image acquisition unit and is displayed on the image sensor, wherein the reference sensor is displayed at the reference sensor target position on the image sensor, at least one verification unit, which is configured to define the reference sensor target position and determine the current position of the reference sensor on the image sensor; and a vehicle using the indirect observation system having the following characteristics: the vehicle has an image acquisition unit arranged in a support element extending distally from the vehicle.

[0013] The invention is based on the idea of ​​reducing the workload generated in the conventional verification of an indirect observation system with an exact orientation of a reference target relative to the vehicle. In particular, by means of the verification, the recording part of the image acquisition unit or the reading part of the image sensor of the image acquisition unit is verified. In this respect, according to the invention, the reference target (which is located outside the vehicle in some environments) is replaced by a so-called reference sensor. The reference sensor is attached to the vehicle body. In this respect, at least one reference sensor is provided per vehicle side so that it is located in the recording part of the image acquisition unit with the switched-on image acquisition unit and is correspondingly shown on the image sensor of the image acquisition unit. If the recording part corresponds to the target recording part, the reference sensor is respectively depicted and defined at the target position on the image sensor. The target position of the reference sensor on the image sensor corresponds to the position that the reference sensor must have in the recording part of the image acquisition unit when the image acquisition unit is ideally adjusted so that the required and desired field of view is optimally displayed to the driver, respectively. In other words, the reference sensor target position corresponds to the position on the image sensor at which the recording portion of the reference sensor of the image acquisition unit on the image sensor is adjusted in the best possible way, i.e. an adjustment that fully meets the visibility requirements for the required and desired field of view.

[0014] In the case of verifying and detecting, respectively, whether the indirect viewing system is adjusted so that its recording part captures the vehicle environment in a required and desired manner, the vehicle environment is captured in the form of image data by an image acquisition unit having an image sensor, and a current position of a reference sensor on the image sensor is detected. The current position of the reference sensor on the image sensor corresponds to the position of the reference sensor that actually exists in the current adjustment of the image acquisition unit in the recording part of the image acquisition unit. After detecting the current position of the reference sensor, the image processing unit or the driver compares the current position of the reference sensor with the target position of the reference sensor. In the case of a deviation between the current position of the reference sensor and the target position of the reference sensor, the recording part of the image acquisition unit or the read part of the image sensor of the image acquisition unit deviates from the ideal adjustment of the recording part of the image acquisition unit and the read part of the image sensor of the image acquisition unit, respectively. As a result, there may be a situation where the required and desired field of view, respectively, is not recorded sufficiently (e.g., incompletely). If the current position of the reference sensor coincides with the target position of the reference sensor on the image sensor, there is no deviation between the recording part or the read part of the image acquisition unit and the ideal adjustment of the recording part and the read part of the image acquisition unit, and the current recording part of the image acquisition unit corresponds to the target recording part of the image acquisition unit. The field of view is displayed as required and desired, respectively. The recording portion of the image acquisition unit corresponds to the portion of the vehicle surroundings that is acquired by the image acquisition unit and depicted on the image sensor. The readout portion of the image sensor corresponds to the portion of the image sensor that is selected for reproduction on the reproduction unit and is taken out of the image sensor.

[0015] In addition to the exact coincidence of the reference sensor current position and the reference sensor target position in order to determine the ideal adjustment of the recording part and the reading part of the image acquisition unit, the position of the reference sensor current position in a defined section around the reference sensor target position is also sufficient to display the required or desired field of view. Therefore, it is not mandatory to have the reference sensor target position and the reference sensor current position exactly coincide in order to reliably display the desired and required field of view on the reproduction unit. The provision of the defined section / area around the reference sensor current position can be performed on the image sensor or on the reproduction unit and serves to balance / compensate for mechanical tolerances of system or vehicle components or inaccuracies in the image recognition process.

[0016] This method for validating an indirect observation system has the advantage that a fixed geometrical reference between a reference target and the vehicle can be achieved by simply attaching the reference sensor directly to the vehicle body, without requiring a cumbersome test setup with a mobile reference target. Furthermore, with the method of the invention, it is no longer necessary to inspect / verify the vehicle in a suitable inspection environment, such as a workshop. Instead, the method can be performed independently at the location of the vehicle, preferably repeatedly at intervals, and also preferably automatically (e.g. at fixed time intervals) or when required (e.g. if the driver wishes) during operation of the observation system. This not only reduces the equipment required for the required test setup, but also saves time for installing the test setup and performing the inspection / verification itself, thereby allowing uninterrupted and economical operation of the indirect observation system.

[0017] Preferably, the reference sensor target position has a fixed geometrical relationship to at least one target field of view captured by the image acquisition unit. The target field of view may be a legally prescribed field of view, such as defined in UN / ECE R46, or a field of view defined by the manufacturer and the user, respectively, and thus a desired field of view. The fixed geometrical relationship between the reference sensor target position and the target field of view ensures that the reference sensor is positioned in the recording portion of the image acquisition unit so that the prescribed or desired field of view is displayed if the reference sensor current position coincides with the reference sensor target position. In this respect, the prescribed or desired field of view depends on the type of vehicle and its geometry.

[0018] According to a preferred embodiment, at least the reference sensor current position is depicted on the reproduction unit and the comparison is performed on the reproduction unit. Preferably, the comparison of the reference sensor current position with the reference sensor target position is performed on the reproduction unit by manually applying a mask (e.g. a foil) or depicting a digital overlay with a fixed reference sensor target position. Thus, a user (e.g. a production person) applies a mask on which the reference sensor target position is indicated on the reproduction unit and compares whether the reference sensor current position is covered on the reproduction unit by the reference sensor target position on the mask. In the absence of covering, the user recognizes in an easy manner that the recording part of the image acquisition unit is displaced or the reading part of the image sensor is displaced and the required or desired field of view may no longer be fully displayed. However, in the case of covering, the user recognizes in an easy manner that the recording part of the image acquisition unit or the reading part of the image sensor is adjusted as required or desired. It is also conceivable to simultaneously display the reference sensor current position and the reference sensor target position on the reproduction unit. Thus, without the use of masks, the user can quickly and reliably recognize that the recording part of the image acquisition unit or the reading part of the image sensor has shifted and the required or desired field of view may no longer be fully displayed. During vehicle travel, the reference sensor current position and the reference sensor target position are even occasionally depicted on the reproduction unit.

[0019] Preferably, the comparison is performed in the image processing unit, for example by a certain calculation algorithm and a computer program, respectively, to compare the reference sensor current position with the reference sensor target position stored in the image processing unit. The computer program may be a graphics program or an image recognition program. For example, with the graphics program, an overlay may be projected onto the image sensor so that the image processing unit can recognize whether the reference sensor current position is consistent with the reference sensor target position. Alternatively, the check / verification of the consistency of the reference sensor current position with the reference sensor target position may be performed with the aid of image recognition, wherein the image acquired by the image acquisition unit is segmented and the separated image segments are analyzed by pattern recognition / pattern matching. The comparison of the reference sensor current position with the reference sensor target position by the image processing unit has the following advantages: the comparison can be performed repeatedly during the operation of the indirect observation system and even during the driving of the vehicle without the need for user operation, which makes the comparison more reliable and more certain and increases the operational safety of the vehicle, since it can be quickly recognized if the current position and the target position no longer coincide.

[0020] Preferably, with the method, not only the reference sensor current position and the reference sensor target position are compared with each other, but it is also possible to check simultaneously whether the current field of view displayed on the image sensor and on the reproduction unit is the required or desired field of view (i.e. the target field of view). Preferably, the comparison of the current field of view and the target field of view is carried out by a position check, i.e. by comparing certain points associated with the target field of view with points of the current field of view. Thus, it can be determined in an easy manner whether the image acquisition unit is in an operating position or in a fixed defined position. For example, in the case of a multi-component articulated camera arm, which can be rotationally folded by a collision with an obstacle or an external impact by a third party, for example at defined irregular or regular time intervals (e.g. once a day, once a week or other time intervals) or after the detection of a specific vehicle state (ignition on / off, engine start, coupling of a trailer, changing image adjustment, etc.), it can be checked whether the camera arm is displaced in the desired direction or whether the camera arm is in a predetermined position, such as a folded position, a parking position, etc. Thus, no separate position switch and folding sensor is required in the camera arm for checking / verifying the visibility of the field of view. For example, if the vehicle is located in a corresponding test device with a reference field of view display, an additional comparison of the field of view position can be performed always or preferably on demand.

[0021] Preferably, in the image processing unit, the comparison of the reference sensor current position and the reference sensor target position is performed at least in an image analysis section of the image sensor. The image analysis section corresponds to a part of the entire image sensor, which the image processing unit uses when applying a computer program for comparing the reference sensor current position and the reference sensor target position. Analyzing a certain part of the image sensor can save computing power and computing time compared to analyzing the entire image sensor. However, it is also conceivable to analyze (i.e. consider) the entire image sensor during the comparison of the reference sensor current position and the reference sensor target position.

[0022] Preferably, the image reading unit includes an image analyzing unit. The image reading unit is a part of the image sensor that is displayed to the driver on the reproduction unit. According to one embodiment of the present invention, the image reading unit is larger than the image analyzing unit. According to another preferred embodiment, the image reading unit does not include the image analyzing unit, i.e., the image analyzing unit is located at another position on the image sensor other than the image reading unit.

[0023] Preferably, the method comprises an additional step of outputting a signal to the driver if the current position of the reference sensor is not equal to the target position of the reference sensor. The signal may be an acoustic, visual and / or tactile signal and may preferably be shown repeatedly to the driver. The acoustic signal may be one or more of an audio warning and an alarm and a voicemail, etc. The visual signal may be one or more of a visual warning notification, such as a red triangle light with an exclamation mark indicated at a reproduction unit, a car dashboard, a head-up display, etc. The visual warning notification may appear repeatedly (e.g. flashing) or may be displayed continuously. The tactile signal may be a vibration of the steering wheel. Various combinations of auditory, visual and / or tactile signals are conceivable. By means of one or more signals, the driver may promptly (i.e. without noticeable time delay) recognize that the recording portion of the image acquisition unit or the reading portion of the image sensor has changed.

[0024] According to a preferred embodiment, if the current position of the reference sensor is not equal to the target position of the reference sensor, the method may include the additional step of performing a calibration action. If the current position of the reference sensor is not equal to the target position of the reference sensor, a calibration action must be performed so that the desired field of view coincides with the target field of view again. The calibration action refers to adjusting and correcting the recording part of the image acquisition unit or the reading part of the image sensor of the image acquisition unit, respectively, so that the image acquisition unit captures the required and desired field of view. And these fields of view are displayed on the image sensor and the reproduction unit accordingly. Through calibration, not only can the recording part and the reading part of the image acquisition unit be verified, that is, their correctness can be checked, but also the recording part and the reading part can be corrected if necessary.

[0025] The output of the signal and the execution of the calibration action can be performed separately or in combination. That is, it is conceivable that the signal is output in order to indicate the deviation between the current position of the reference sensor and the target position of the reference sensor to the driver or production personnel, but the deviation is not corrected. Alternatively, the signal may not be sent to the driver or production personnel, but the deviation may be corrected directly after the deviation between the current position of the reference sensor and the target position of the reference sensor is determined. Alternatively, the signal output and the correction process can also be performed directly afterwards.

[0026] Preferably, the calibration action includes adjusting (calibrating) the recording part of the image acquisition unit or the reading part of the image sensor so that the reference sensor current position is equal to the reference sensor target position, that is, the reference sensor current position coincides (is consistent) with the reference sensor target position on the image sensor, that is, the reference sensor current position and the reference sensor target position have the same position on the image sensor. Therefore, it can be ensured that the driver can reliably observe the vehicle environment.

[0027] Preferably, the adjustment of the recording part of the image acquisition unit or the reading part of the image sensor is performed manually or electrically by aligning at least a part of the image acquisition unit and / or digitally by adjusting at least one image reading part on the image sensor. Thus, the orientation of at least one part of the image acquisition unit can be performed manually, for example, by displacement of an adjustment screw of the image acquisition unit at the body of the vehicle or the support structure supporting the acquisition unit. Another example is the displacement of the support structure and parts of the support structure relative to each other. Alternatively, the orientation can also be achieved by adhering the acquisition unit to the body of the vehicle or the support structure supporting the acquisition unit in a suitable position and posture, respectively. Furthermore, alternatively or additionally, the orientation of at least a part of the image acquisition unit can occur electronically, for example by using a servo motor, which automatically moves the optics of the image acquisition unit, for example. The orientation of the image reading part can be performed manually by a corresponding input medium (for example a joystick, a touch screen, a door control module, an input button on a monitor, etc.), or it can be performed automatically by a calibration program stored in the image processing unit. Alternatively or additionally, the adaptation of at least one image reader may occur digitally by changing the image reader on the image sensor so that the reference sensor current position coincides with the reference sensor target position. For example, this may occur by moving the reader portion on the image sensor pixel by pixel.

[0028] The calibration action is caused by a signal received in the image processing unit. Preferably, the signal can be received during the operation of the indirect observation system. The signal can be a manual input by a user (e.g. a driver or production personnel) or can be output by software in a clocked manner (time interval, mode) or by a defined vehicle function (ignition on / off, engine start, trailer connection, change of image adjustment, etc.).

[0029] The target field of view is preferably a legally required field of view. For example, the target field of view corresponds to one of the fields of view defined in UN / ECE R46, for example, a field of view of group II or IV. The legally required field of view has a fixed relationship to the driver's viewpoint as defined in UN / ECE R46. Therefore, in this case, there is also a fixed geometric relationship between the driver's viewpoint and the reference sensor, which further increases the reliability that the driver actually observes the field of view he should observe.

[0030] Preferably, the indirect viewing system is a mirror replacement system which completely replaces the legally required vehicle mirrors.

[0031] According to another aspect of the present invention, an indirect observation system for a vehicle is provided, which is configured to perform the above method. The indirect observation system includes at least one image acquisition unit having an image sensor, which is configured to record image data of at least one recording portion around the vehicle; at least one image processing unit, which is configured to process the image data acquired by the image acquisition unit; and at least one reproduction unit, which is configured to reproduce the image data processed by the image processing unit. In addition, the indirect observation system includes at least one reference sensor, which is configured to be attachable to a defined position on the vehicle, and is located in the recording portion of the image acquisition unit when the indirect observation system is installed on the vehicle, and is displayed on the image sensor, wherein the reference sensor displays a reference sensor target position on the image sensor. In addition, the indirect observation system includes at least one verification unit, which is configured to define a reference sensor target position and to determine a reference sensor current position on the image sensor.

[0032] As image acquisition unit, any digital image acquisition unit having an image sensor and suitable for recording / capturing the vehicle environment in the form of image data may be considered, such as a camera with CMOS or CCD technology. As image processing unit, any control unit (ECU) suitable for issuing and receiving signals and commands may be considered. Thus, the image processing unit may include a single image processing module or a plurality of image processing modules, which are arranged either in one position or in different positions in the observation system or are arranged completely or partially in the vehicle. As reproduction unit, any monitor, any display, etc. suitable for displaying the image data recorded by the image processing unit may be considered, such as a TFT monitor, an LCD monitor, etc.

[0033] Preferably, the observation system further comprises a calibration unit, which is configured to perform a calibration action. Therefore, with the indirect observation system, it is possible not only to determine whether the reference sensor current position is consistent with the reference sensor target position, but also to correct the deviation if there is a deviation between the reference sensor current position and the reference sensor target position, thereby adjusting the recording part of the image acquisition unit or the reading part of the image sensor so that the reference sensor current position on the image sensor and the reproduction unit coincides with the reference sensor target position, i.e., is located at the same position or at least is located in a limited area around the reference sensor target position.

[0034] Preferably, the reference sensor comprises a geometric pattern. For example, the reference sensor can be a crosshair, a triangle, a circle, and if so, can be single-color or multi-color, which can be attached to a suitable position of the vehicle body. Alternatively or additionally, the reference sensor can also be a part of the vehicle body (in particular the vehicle contour) which has a special shape that can be identified by means of image recognition. For example, the reference sensor can correspond to the edge of the rear part of the vehicle (for example the cab or the vehicle assembly). Alternatively, the reference sensor can also be a flashing signal of a wheel or a turn indicator of the vehicle. In addition, the special shape can also be identified by the user on the reproduction unit.

[0035] Alternatively or additionally, the reference sensor can be configured for reflecting light. For example, the reference sensor can be a reflector, if so, as an adhesive label / sticker, or can include a reflective tape / strip. Thereby, the reference sensor can also be identified in a dark vehicle environment in the presence of a light source on the image sensor or the reproduction unit in the vehicle environment.

[0036] In addition, the reference sensor can be the light source itself. For example, the reference sensor can be an LED, an infrared lamp, a laser, a light bulb, etc. Thus, the reference sensor can be identified on the image sensor or the reproduction unit in darkness (e.g. at night, in a tunnel or in bad weather conditions) even if no other light sources are present in the vehicle environment. Thus, the light source can be permanently illuminated, flashing or can be switched on only when a specific event occurs (e.g. when the ignition switch is turned on, a trailer is coupled, etc.), or can be switched on manually by a user (e.g. a driver or production staff).

[0037] Preferably, the light source can be a lamp present on the vehicle, such as a vehicle boundary lamp, a surrounding lamp, a rear lamp, an entry lamp, a signal indicator, etc. Even lamps on the vehicle can be used as reference sensors, which do not shine toward the image acquisition unit, but are nevertheless located in the recording part of the image acquisition unit, such as boundary lamps located at the rear of the vehicle or in the cab or vehicle assembly. In this case, an opening must be provided in the lamp housing, through which the light shines toward the image acquisition unit.

[0038] In the case of a light source used as a reference sensor, the light source can furthermore advantageously be configured for detecting contamination of the optics of the image acquisition unit on the reproduction unit. By illuminating the optics of the image acquisition unit (e.g. a lens), if foreign particles are located on the optical element, the foreign objects can be recognized well on the image sensor, i.e. more clearly than without additional illumination. By illuminating the foreign particles, a high-contrast and prominent depiction of the foreign particles is produced directly on the image sensor, so that the alleged contamination of the optical element can be automatically recognized on the image sensor by image recognition or can be displayed to the driver on the reproduction unit.

[0039] Preferably, the observation system comprises at least two acquisition units, each of which is associated with a respective reference sensor, or a common reference sensor is associated with a plurality of acquisition units.

[0040] According to a preferred embodiment, the viewing system is a mirror replacement system.

[0041] According to a further aspect, a vehicle having an observation system as described above is provided, wherein the image acquisition unit is arranged in a retaining element extending distally from the vehicle. The retaining element may be a camera arm, characterised in that its extension in the longitudinal direction is much greater than its extension in the transverse direction. Preferably, the image acquisition unit is arranged at the end of the camera arm remote from the vehicle in order to capture the vehicle environment in a suitable manner. The vehicle is preferably a passenger car or a commercial vehicle. As a commercial vehicle, a truck with a cab and a preferably rigid assembly, for example a metal assembly, comes into consideration. Alternatively, the term "vehicle" may also include a truck with a cab and a trailer.

[0042] Preferably, the vehicle is a commercial vehicle and the reference sensor is arranged outside the vehicle cab. Alternatively, the reference sensor can also be attached to a side surface of the vehicle, or the reference sensor can be attached to the front surface of the vehicle. This is particularly advantageous if ECE / UN R46 applies. In addition, the reference sensor can also be attached to a vehicle assembly of the vehicle, such as a box or a side panel wall.

[0043] The reference sensor can be attached to the vehicle directly or can be attached to the vehicle via a reference sensor support element. The support element can be a component that protrudes from the vehicle in its mounted state and which is provided with the reference sensor at its end facing away from the vehicle, for example adhered thereto or screwed thereto.

[0044] According to a preferred embodiment, the reference sensor is releasably connected to the vehicle. In this respect, the reference sensor is only temporarily attached for the calibration action (e.g. by means of a magnetic base, screw fixing, hanging connection, etc.) and is removed afterwards. The reference sensor can also be non-releasably connected to the vehicle so that it is permanently present on the vehicle, for example by means of an adhesive label / sticker, paint or corresponding varnish, a lamp, a separate component, a vehicle reference that contrasts with the environment, such as the rear edge of the cab, a wheel housing, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the following, the present invention will be exemplarily described based on the accompanying drawings, in which:

[0046] Figure 1 The present invention is a schematic diagram of the structure of an observation system capable of executing the method of the present invention.

[0047] Figure 2A top view of a vehicle with an image acquisition unit and a target field of view.

[0048] Figure 3 A side view of a vehicle with an image acquisition unit and a target field of view.

[0049] Figure 4 A reproduction unit is shown, which shows Figure 2 and 3 The vehicle environment shown. ;

[0050] Figure 5 The image sensor is displayed with the reference sensor current position and the reference sensor target position as well as the current field of view and the target field of view shown thereon.

[0051] Figure 6 A reproduction unit is shown, which shows Figure 2 and Figure 3 The vehicle environment shown has a reference sensor on the side of the vehicle;

[0052] Figure 7 A reproduction unit is shown, which shows Figure 6 The vehicle environment shown, wherein reference sensors are arranged at the target position and the current position and the corresponding current field of view and target field of view respectively; and

[0053] Figure 8 A flow chart is shown which comprises the essential steps of a method for checking and calibrating, respectively, an indirect viewing system according to the invention. DETAILED DESCRIPTION

[0054] Figure 1 The schematic diagram of an indirect observation system 1 which can perform the method according to the invention is shown. The observation system 1 comprises an image acquisition unit 10 (eg a camera) having an image sensor 20, an image processing unit 30 (eg an ECU) and a reproduction unit 40 (eg a monitor). Figure 1 The observation system 1 shown in FIG. 1 is shown in an ideal vehicle environment, in which a vehicle 60 (see the rectangle shown in double-dashed lines) and a target field of view 71 (see the shaded rectangle) associated with the vehicle 60 are shown. The current ideal vehicle environment means that the target field of view 71 is shown to the driver (not shown) of the vehicle 60 on the reproduction unit 40 as required. Figure 1 The vehicle 60 is shown traveling in a forward direction. Figure 1 Middle direction Figure 1 on the right side, traveling backwards towards Figure 1 The acquisition unit 10 has a recording portion 11, which opens and expands from the camera 10 to the rear side of the vehicle 60.

[0055] Furthermore, the observation system 1 comprises a reference sensor 50. Figure 1 , the reference sensor 50 is attached to the left outer side of the schematically illustrated vehicle 60 .

[0056] The target field of view 71 is arranged at the oblique rear of the left side of the vehicle 60, and may be a field of view required by law (for example, a field of view of Group II or Group IV required by UN / ECER46). Figure 1 As shown, the target field of view 71 has a fixed geometric reference 73 relative to the reference sensor 50. That is, the arrangement of the target field of view 71 relative to the reference sensor 50 is known and remains constant even in an ideal vehicle environment.

[0057] Figure 2 A top view of a vehicle 60 (now a truck) is shown. The vehicle 60 has a cab 61 and a vehicle assembly 62 (e.g., a dump truck, a cooler, a box, a car transporter, etc.). The forward travel direction of the truck 60 is Figure 2 The truck 60 is traveling in the direction of the left side. Figure 2 The following description of the vehicle environment on the left side of the truck 60 is also applicable to the right side of the truck 60 even if not shown.

[0058] The truck has an image acquisition unit 10 on the left side of the tractor (particularly the cab). The image acquisition unit 10 acquires the vehicle environment to the left and behind the truck 60 and has a recording portion 11 that extends from the image acquisition unit 10 to the rear of the truck 60 in a horizontal plane parallel to the road surface. Therefore, the recording portion 11 of the image acquisition unit 10 is called a recording cone 11.

[0059] On the left side / beside the truck 60, there is arranged Figure 1 71. The target field of view 71 extends to the rear of the truck 60 at a predetermined distance behind the driver's viewpoint (not shown) and expands rearward at a specific angle. Currently, the target field of view 71 corresponds to the field of view II of UN / ECE R46, i.e. the primary mirror field of view. However, the target field of view may also correspond to any other field of view, which may be a legally required field of view or a desired field of view, i.e. a field of view predetermined by the manufacturer or the user.

[0060] At the rear edge of the cab 61 of the truck 60, there is arranged Figure 1 The reference sensor 50 is shown. Figure 2 As shown, the reference sensor 50 is located in the recording cone 11 of the image acquisition unit 10. The reference sensor 50 can also be attached to the vehicle assembly 62, as long as the assembly is a rigid assembly.

[0061] Figure 3 Shown in side view Figure 2 Vehicle environment. Figure 3 As shown, the recording part 11 of the image acquisition unit 10 is not only extended from the image acquisition unit 10 to the rear of the truck 60 in a horizontal plane parallel to the road surface, but also extended to the rear in a plane perpendicular to the road surface and parallel to the left outer wall of the truck. Figure 3 is shown as a large black line in the road surface plane. Figure 3 As further shown, the reference sensor is arranged at the upper left rear corner of the tractor of the truck 60 and is captured by the recording cone 11 of the image acquisition unit 10 .

[0062] Figure 4 Shows Figure 1 The reproduction unit 40 is shown. Figure 4 In the reproduction unit 40, Figure 2 and Figure 3 The ideal vehicle environment shown. Figure 4 The person schematically depicted is not shown in Figure 2 and Figure 3 In. Figure 4 For the sake of clarity, only the Figure 2 and Figure 3 From Figure 4 It can be seen that the reference sensor 50 is arranged on the tractor of the truck 60 through the reference sensor support element 53. Specifically, the reference sensor 50 is attached to the end of the reference sensor support element 53, which protrudes away from the tractor of the truck 60. The reference sensor 50 may be a light reflecting element or a lamp that emits light to the front of the truck 60.

[0063] Figure 5 It shows that Figure 1 The image sensor 20 in the image acquisition unit 10 is shown, and a verification process performed by the image processing unit 30 is schematically shown, wherein the recording part 11 of the image acquisition unit 10 or the image reading part 22 of the image sensor is verified by comparing the reference sensor current position 52 and the reference sensor target position 51 on the image sensor 20.

[0064] The image sensor 20 has a rectangular shape. Figure 5 In the embodiment of the present invention, the length of the image sensor 20 extending vertically is longer than the length extending horizontally. On the image sensor 20, the entire vehicle environment located within the recording cone 11 is depicted. A portion of the image data shown on the image sensor 20 is read as the image reading section 22 (see the rectangle with a thin dotted line) and is transmitted to the reproduction unit 40 for display. It is also possible to transmit the image data of the entire image sensor 20 to the reproduction unit 40 for display.

[0065] In the upper left corner of the image reading section 22, an image analysis section 21 is arranged (see rectangle with approximately dashed lines). In the image analysis section 21, a reference sensor target position 51 is indicated. The reference sensor target position 51 on the image sensor 20 corresponds to the position on the image sensor 20 where the reference sensor 50 should be depicted if the recording section 11 of the image acquisition unit 10 is in the required and desired adjustment, respectively. When the recording section 11 of the image acquisition unit 10 is in the required and desired adjustment, respectively, the driver sees the required and desired vehicle environment, for example the required and desired target field of view 71, respectively, on the reproduction unit 40.

[0066] In the image analysis unit 21, a reference sensor current position 52 is also shown. If the image acquisition unit 10 acquires the vehicle environment, the reference sensor current position 52 on the image sensor 20 corresponds to the position of the reference sensor 50 actually depicted on the image sensor 20. Figure 5 As shown, the reference sensor current position 52 is not at the same position as the reference sensor target position 51. The reference sensor target position 51 has a fixed geometric relationship 73 with the target field of view 71, and the current field of view 72 is also displayed on the image sensor 20 of the image acquisition unit 10 in a manner offset relative to the target field of view 71. In this case, the driver can only partially see / observe the required and desired vehicle environment on the reproduction unit 40 (see Figure 5 The overlapping part of the target field of view 71 and the current field of view 72).

[0067] exist Figure 5In the embodiment shown, the deviation of the reference sensor current position 52 and the reference sensor target position 51 on the image sensor 20 is detected by a suitable computer program stored in the image processing unit 30 (e.g. by image recognition) and displayed to the driver by an audio warning or a corresponding display on the reproduction unit 40 or the instrument panel. The driver can then correct the deviation of the reference sensor current position 52 and the reference sensor target position 51 by, for example, manually adjusting the image acquisition unit 10 so that the reference sensor current position 52 is equal to the reference sensor target position 51. However, in a next step or an alternative step of the signal output, the image processing unit 30 can also correct the depiction error on the image sensor, i.e. the reference sensor current position 52 is not equal to the reference sensor target position 51, so that the indirect viewing system can be calibrated. The calibration of the recording part 11 of the image acquisition unit 10 can be performed automatically by the image processing unit 30. In general, the determination whether the reference sensor current position 52 is equal to the reference sensor target position 51 is based on a signal (e.g. a corresponding command of the driver), a vehicle event or the start of a corresponding calibration procedure. The vehicle event can be the start of the vehicle, the opening of the ignition, the coupling of a trailer, etc. The calibration program determines the reference sensor current position 52 in a clock manner through corresponding software, compares the reference sensor current position 52 with the reference sensor target position 51 , and automatically corrects the reference sensor current position 52 to make it coincide with the reference sensor target position 51 .

[0068] like Figure 5 As further shown, a reference sensor target portion 23 is defined around the reference sensor target position 51. The reference sensor target portion 23 defines an area on the image sensor 20 in which the reference sensor 50 must at least be located in order to be able to acquire the required and desired fields of view using the image acquisition unit 10, respectively, to depict them on the image sensor 20 and to display them on the reproduction unit 40. The reference sensor target portion 23 is predefined by the vehicle manufacturer or the viewing system manufacturer and usually comprises a portion that is symmetrical around the reference sensor target position 51. An asymmetrical extension of the reference sensor target portion 23 around the reference sensor target position 51 is also possible. Thus, in order to calibrate the viewing system 1, the reference sensor current position 52 can also be moved into the reference sensor target portion 23, but does not necessarily have to be located exactly at the reference sensor target position 51.

[0069] exist Figure 6 In FIG. 4 , a reproduction unit 40 is shown, and its display content is similar to Figure 4 The display content of the reproduction unit is basically the same. Figure 6 , a reference sensor 50 is shown attached to the lower right rear corner of a cab 61 of a truck 60 . Figure 4The reference sensor 50 in is a crossline attached to the outer wall of the cab. For example, the reference sensor 50 can be a permanent adhesive label / sticker or can be attached to the outer wall of the cab when the truck 60 disappears. The reference sensor is thus permanently fixed to the outer wall of the cab. Alternatively, however, the reference sensor 50 can also be a (releasable) adhesive label / sticker that can be attached to the outer wall of the cab / truck via a magnetic base or can be releasably configured from the outer wall of the cab / truck in another way so that it can be fixed only when needed (i.e. for a planned verification), if necessary, the indirect observation system 1 is calibrated to the body of the truck. In addition, the reference sensor can be attached to all conceivable and suitable locations on the body of the truck 60, however, it can also be attached to a fixed defined part of the vehicle assembly, such as a box. Alternatively, a special shape of the body of the truck (e.g. a wheel, the rear edge of the cab 61 or the vehicle assembly 62) can form the reference sensor 50 itself.

[0070] Figure 7 Again, it shows Figure 6 A reproduction unit 40 and a verification process performed by the image processing unit 30, wherein a verification of the recording part 11 of the image acquisition unit 10 is performed by comparing a reference sensor current position 52 and a reference sensor target position 51 on the reproduction unit 40, for example digitally via a cover layer or manually by applying foils, on each of which a reference sensor target position is defined. The cover layer and the foil now respectively correspond to the verification unit.

[0071] exist Figure 6 In the example, only the target situation is displayed on the reproduction unit 40, while Figure 7 In FIG. 4 , the target situation and the current situation are displayed on the reproduction unit 40. Specifically, in Figure 6 , the reference sensor 50 is located at the reference sensor target position 51 in the target situation, and is located at the reference sensor current position 52 in the current situation. The reference sensor current position 52 is displaced relative to the reference sensor target position 51, and the current field of view 72 is also displaced relative to the target field of view 71.

[0072] exist Figure 6In the embodiment shown, the deviation between the reference sensor current position 52 and the reference sensor target position 51 on the image sensor 20 is detected by a suitable computer program stored in the image processing unit 30, for example, by image recognition, and displayed to the driver by superimposing the target situation on the current situation on the reproduction unit 40. If so, the deviation of the current situation from the target situation can also be displayed to the driver on the reproduction unit 40 by an additional signal, for example, by an audio warning or a corresponding display on the reproduction unit 40 or on the instrument panel. The driver can then, for example, manually correct the deviation of the reference sensor current position 52 from the reference sensor target position 51 by adjusting the image acquisition unit 10, so that the reference sensor current position 52 is equal to the reference sensor target position 51. However, in a further step or alternative step of the signal output, the image processing unit 30 can also correct the depiction error on the image sensor itself by a suitable calibration program, i.e. the reference sensor current position 52 is not equal to the reference sensor target position 51, and thus the indirect viewing system can be calibrated. The calibration of the recording part 11 of the image acquisition unit 10 by the image processing unit 30 can be performed automatically. Generally, the determination of whether the reference sensor current position 52 is equal to the reference sensor target position 51 is based on a signal (e.g., a corresponding command of the driver), a vehicle event, or the start of a corresponding calibration program. The vehicle event may be the start of the vehicle, the switching on of the ignition switch, the coupling of the trailer, etc. The calibration program performs the determination of the reference sensor current position 52 in a clock manner through corresponding software, compares the reference sensor current position 52 with the reference sensor target position 51, and automatically corrects the reference sensor current position 52 to make it consistent with the reference sensor target position 51.

[0073] Despite Figure 6 The reference sensor 50 is shown to be arranged at the rear of the cab 61, however Figure 7 The reference sensor 50 is shown disposed at the rear of an assembly 62 of a truck 60 .

[0074] exist Figure 8 , flow charts describing the verification process and the calibration process, respectively, are shown. In step S10, the image acquisition unit 10 has at least one image sensor 20 and is configured to acquire image data of at least one recording portion 11 around the truck; the ECU acts as an image processing unit 30, which is configured to process the image data acquired by the image acquisition unit 10, and the monitor acts as a reproduction unit 40, which is configured to reproduce the image data processed by the image processing unit 30. In addition, in step S10, a reference sensor is provided, which is arranged at a defined position on the truck 60, so that the reference sensor 50 is located in the recording portion of the image acquisition unit 10 during operation of the observation system 1 and is depicted on the image sensor 20.

[0075] In step S20 , a reference sensor target position 51 is correspondingly defined / determined on the image sensor 20 , wherein the reference sensor 51 is depicted in an ideal vehicle environment.

[0076] In step S30 , the image acquisition unit acquires image data of the recording portion 11 around the vehicle 60 on the image sensor 20 including the reference sensor 50 .

[0077] In step S40 , the image reading section 22 reading the image data from the image sensor 20 is displayed on the reproduction unit 40 .

[0078] In step S50, the reference sensor current position 52 of the reference sensor 50 is determined on the image sensor 20, and in step S60, the reference sensor current position 52 and the reference sensor target position 51 are compared with each other to determine whether the reference sensor current position 52 is equal to the reference sensor target position 51 (S70).

[0079] If the reference sensor current position 52 is equal to the reference sensor target position 51 ("Yes" in S70), the verification process returns to step S50 and determines the reference sensor current position 52. The redetermination of the reference sensor current position 52 can occur when there is a signal, such as a manual signal from the driver or a signal automatically generated (for example, after a certain period of time), or it can occur immediately after determining that the reference sensor current position 52 is equal to the reference sensor target position 51, without a time delay, that is, in the query program loop.

[0080] If the reference sensor current position 52 is not equal to the reference sensor target position 51 ("No" in S70), the process either proceeds to step S71 and outputs a signal to the driver, which shows the driver the deviation of the reference sensor current position 52 relative to the reference sensor target position 51, or proceeds to step 72, in which the recording part 11 of the camera 10 is calibrated, i.e., corrected, so that the reference sensor current position 52 is equal to the reference sensor target position 51. It is also conceivable that steps S71 and S72 occur subsequently in time, i.e., first a signal is output to the driver, which shows the deviation of the reference sensor current position 52 relative to the reference sensor target position 51, and immediately following the output of the signal, a correction of the reference sensor current position 52 is performed so that the reference sensor current position 52 is equal to the reference sensor target position 51.

[0081] Figure 8The process is terminated after step S71, and after step S72, it can return to step S70 again to check whether the reference sensor current position 52 is equal to the reference sensor target position 51, or it can also be terminated after step S72.

[0082] It is explicitly pointed out that all features disclosed in the present specification and / or claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure and for the purpose of limiting the claimed invention independently of the feature composition in these embodiments and / or claims. It is explicitly pointed out that all indications of value ranges or groups of entities disclose every possible intermediate value or intermediate entity, in particular as a limitation of the value range, for the purpose of original disclosure and for the purpose of limiting the claimed invention.

[0083] List of reference numerals:

[0084] 1: Indirect observation system

[0085] 10: Image acquisition unit, camera

[0086] 11: Recording section, recording cone

[0087] 20: Image Sensor

[0088] 21: Image Analysis Department

[0089] 22: Image reading unit

[0090] 23: Reference sensor target section

[0091] 30: Image processing unit, ECU

[0092] 40: Reproduction unit, monitor

[0093] 50: Reference sensor

[0094] 51: Reference sensor target position

[0095] 52: Reference sensor current position

[0096] 53: Reference sensor support element

[0097] 60: Vehicles

[0098] 61: Cab

[0099] 62: Vehicle assembly

[0100] 71: Target Field of View

[0101] 72: Current field of view

[0102] 73: Geometric relations

Claims

1. A method for verifying an indirect observation system (1) of a vehicle (60), comprising: Providing (S10) at least one image acquisition unit (10) having at least one image sensor (20) and configured to acquire image data of at least one recording portion (11) to the side and rear of the vehicle (60), providing (S10) at least one image processing unit (30) configured to process the image data acquired by the image acquisition unit (10), providing (S10) at least one reproduction unit (40) configured to reproduce the image data processed by the image processing unit (30), providing (S10) at least one reference sensor (50) at a defined position of the vehicle (60), such that the reference sensor (50) is located in the recording portion (11) of the image acquisition unit (10) and is displayed on the image sensor (20), wherein the reference sensor (50) is defined as a reference sensor target position (51) on the image sensor (20) (S20), collecting (S30) image data of the at least one recording portion (11) around the vehicle (60) on the image sensor (20) including the reference sensor (50), reproducing (S40) at least one image reading portion (22) read from the image data of the image sensor (20) on the reproducing unit (40), determining (S50) a reference sensor current position (52) of the reference sensor (50) on the image sensor (20), and The reference sensor current position (52) is compared with the reference sensor target position (51) (S60, S70) to determine whether the reference sensor current position (52) is equal to the reference sensor target position (51).

2. The method according to claim 1, wherein: The reference sensor target position (51) has a fixed geometric relationship (73) with at least one target field of view (71) acquired by the image acquisition unit (10).

3. The method according to claim 1 or 2, wherein at least the current position (52) of the reference sensor is depicted on the reproduction unit (40), and the comparison (S60, S70) is performed on the reproduction unit (40).

4. The method according to claim 1 or 2, wherein: The comparison (S60, S70) is performed in the image processing unit (30).

5. The method according to claim 3, wherein: The method comprises the additional step of comparing the current field of view (72) with the target field of view (71).

6. The method according to claim 4, wherein: The comparison of the reference sensor current position (52) with the reference sensor target position (51) is performed by the image processing unit (30) in at least one image analysis section (21) of the image sensor (20).

7. The method according to claim 6, wherein the image reading section (22) includes the image analyzing section (21).

8. The method according to claim 1, wherein: If the reference sensor current position (52) is not equal to the reference sensor target position (51), the method comprises the additional step of outputting a signal to the driver.

9. The method according to claim 1, wherein: If the reference sensor current position (52) is not equal to the reference sensor target position (51), the method comprises the additional step of performing a calibration action.

10. The method according to claim 9, wherein: The calibration action includes adjusting the recording part (11) of the image acquisition unit (10) so that the reference sensor current position (52) is equal to the reference sensor target position (51).

11. The method according to claim 10, wherein: The adjustment of the recording part (11) of the image acquisition unit (10) is performed by aligning at least a part of the image acquisition unit (10) and / or by adjusting at least one image reading part (22) on the image sensor (20).

12. The method according to claim 9, wherein: The calibration action takes place via a signal received from the image processing unit (30).

13. The method according to claim 2, wherein: The target field of view (71) is the field of view required by law.

14. The method according to claim 1, wherein: The indirect viewing system (1) is a mirror replacement system.

15. An indirect observation system (1) for a vehicle (60), configured to perform a method according to any one of claims 1 to 14, comprising: The at least one image acquisition unit (10) comprises an image sensor (20) and is configured to acquire image data of at least one recording portion (11) to the side and rear of the vehicle (60), The at least one image processing unit (30) is used to process the image data collected by the image collection unit (10); the at least one reproduction unit (40) being configured to reproduce the image data processed by the image processing unit (30), The at least one reference sensor (50) is configured to be attachable to a defined position on the vehicle (60), and when the indirect observation system (1) is installed on the vehicle (60), the reference sensor (50) is located in the recording part (11) of the image acquisition unit (10) and displayed on the image sensor (20), wherein the reference sensor (50) displays the reference sensor target position (51) on the image sensor (20), At least one verification unit is configured to define a reference sensor target position (51) and determine a reference sensor current position (52) on the image sensor (20).

16. The indirect observation system (1) according to claim 15, wherein: The observation system further comprises a calibration unit configured to perform a calibration action.

17. The indirect observation system (1) according to claim 15 or 16, wherein: The reference sensor (50) comprises a geometric pattern.

18. The indirect observation system (1) according to claim 15, wherein: The reference sensor (50) reflects light.

19. The indirect observation system (1) according to claim 15, wherein: The reference sensor (50) is a light source.

20. The indirect observation system (1) according to claim 19, wherein: The light source is a lamp present at the vehicle (60).

21. The indirect observation system (1) according to claim 19, wherein: The light source is configured to indicate contamination of the optics of the image acquisition unit (10) on the reproduction unit (40).

22. The indirect observation system (1) according to claim 15, further comprising at least two acquisition units, wherein a reference sensor (50) is associated with each acquisition unit respectively, or a common reference sensor (50) is associated with the at least two acquisition units.

23. The indirect observation system (1) according to claim 15, wherein: The viewing system (1) is a mirror replacement system.

24. A vehicle (60) having an indirect observation system according to any one of claims 15 to 23, wherein: The image acquisition unit (10) is arranged in a support element extending distally from the vehicle (60).

25. The vehicle (60) of claim 24, wherein: The reference sensor (50) is attached to the outside of the cab of the vehicle.

26. The vehicle (60) of claim 24, wherein: The reference sensor (50) is attached to a side surface of the vehicle (60).

27. The vehicle (60) of claim 24, wherein: The vehicle (60) is a commercial vehicle, and the reference sensor (50) is attached to a front surface of the vehicle (60).

28. The vehicle (60) of claim 24, wherein: The reference sensor (50) is attached to a vehicle assembly of the vehicle (60).

29. The vehicle (60) according to any one of claims 24 to 28, wherein: The reference sensor (50) is attached to the vehicle (60) via a reference sensor support element.

30. The vehicle (60) according to any one of claims 24 to 28, wherein: The reference sensor (50) is releasably connected to the vehicle (60).

Images