Calibration method and calibration system

Abstract

The present invention relates to a calibration method for calibrating a projection (10) of an image sequence on a target surface (12) of an instrument panel (14) of a motor vehicle by means of a projection unit (18) of the motor vehicle, the method having the following steps: performing a first test sequence, performing a second test sequence, determining at least one target surface boundary (40) of the target surface (12), and limiting second test images (36) of the projection unit (18) to the at least one target surface boundary (40) of the target surface (12) using a limiting unit of the control unit (32) for performing the calibration of the target surface (12). The invention also relates to a calibration system (50) for carrying out the calibration method.

Description

[0001] Description

[0002] Calibration procedure and calibration system

[0003] The invention relates to a calibration method having the features of independent patent claim 1 and a calibration system having the features of independent patent claim 9.

[0004] Currently, more and more vehicles are entering series production with a projection system. In these vehicles, the projector is manually adjusted during factory production to align the projection to an optimal surface. The position and angle of the projector's projection are adjusted using mechanical adjustment screws, thus adapting the projected image to the surface.

[0005] Manual adjustment of the desired projection position is vehicle-specific and therefore complex in the factory process and therefore correspondingly costly.

[0006] It is therefore an object of the present invention to at least partially overcome at least one of the disadvantages described above. In particular, the object of the invention is to provide a calibration method that calibrates the projection position simply and with reduced effort, while simultaneously being cost-effective.

[0007] The above object is achieved by a calibration method having the features of independent patent claim 1 and by a calibration system having the features of independent patent claim 9. Further features and details of the invention emerge from the subclaims, the description, and the drawings. Features and details described in connection with the calibration method according to the invention naturally also apply in connection with the calibration system according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other. A first aspect of the invention is a calibration method for calibrating a projection of an image sequence onto a target surface of an instrument panel of a motor vehicle using a projection unit of the motor vehicle, comprising the following steps:

[0008] - Execute an initial test sequence by following these steps:

[0009] - Projecting at least two, preferably at least three, more preferably at least four, first test images by means of the projection unit onto a projection surface of the instrument panel, wherein the two first test images are projected over the entire area of ​​the projection surface, wherein the first test images are projected one after the other, wherein each test image is assigned a brightness;

[0010] - capturing a first reflection for each projected first test image in an interior of the motor vehicle during the execution of the first test sequence by means of a camera unit;

[0011] - Determining a maximum brightness in the interior in one of the first reflections and assigning the maximum brightness to the brightness of one of the first test images for use as brightness in a second test sequence by means of a determination unit of a control unit,

[0012] - Execute the second test sequence by following these steps:

[0013] - Projecting at least two, preferably at least three, more preferably at least four, test strips with different strip widths by means of the projection unit onto a projection surface of the instrument panel, wherein the test strips are projected one after the other;

[0014] - capturing a second reflection for each projected test strip in the interior of the motor vehicle during the second test sequence by means of the camera unit;

[0015] - Determining a minimum brightness in the interior in one of the second reflections and assigning the minimum brightness to the strip width of one of the test strips for use as the strip width for determining the target area boundary by means of the determination unit of the control unit,

[0016] - Determining at least one target area boundary of the target area by the following steps:

[0017] - Projecting at least two, preferably at least three, more preferably at least four, second test images onto the projection surface by means of the projection unit, wherein the second test images are projected one after the other, wherein the second test images each have a stripe in the edge region with the stripe width having the minimum brightness of the second reflection,

[0018] - Capturing a third reflection of the second test images in the interior using the camera unit,

[0019] - Determining the target area boundary of the target area using the detection unit of the control unit when the camera unit detects a third reflection,

[0020] - Limiting the second test images of the projection unit to the at least one target area boundary of the target area by means of a boundary unit of the control unit for carrying out the calibration of the target area.

[0021] In this context, brightness refers to the luminous intensity that can be generated by projection or reflection. The brightness of the first test images is the luminous intensity of the test image being emitted or projected. The brightness can depend on the color of the test image or an explicit change in the brightness of the projection unit's light source, i.e., a dimming process of the projection unit's light source.

[0022] Accordingly, the execution of the first test sequence, ie, the projection of the first test images, can be carried out with test images of different colors.

[0023] The first test images are projected across the entire surface of the vehicle's instrument panel, i.e., onto a projection surface. The camera unit then captures the first reflection of the projected first test image in the vehicle's interior, i.e., the reflection of the brightness or color of the first test image by the interior, for example, the seat covers or the steering wheel.

[0024] The first reflection is therefore the residual radiation reflected by the interior, whereby the projection surface onto which the projection unit projects the test images differs from the interior of the vehicle. This means that the first reflection is determined in an area of ​​the vehicle that is not directly illuminated by the projection unit. The detection unit then determines the maximum brightness of the light reflected by the interior, i.e., the first reflection of the projected test images on the interior of the vehicle.

[0025] The maximum brightness is used to select the brightness, and thus either an optimal brightness setting of the light source of the projection unit and / or the color of the first test image.

[0026] As already mentioned, the test pattern that produces the maximum brightness in the interior is used to execute the second test sequence.

[0027] The brightness, or rather the maximum brightness, of the first test image is then used for the test strips, which have different strip widths. This strip width of the test strips is reduced until the light intensity of the test strips is so low that the camera unit can only detect darkness, meaning that no second reflection is detected.

[0028] The strip width of the test strip at which the minimum brightness, ie, a minimum light intensity, is determined, ie, the strip width at which the camera unit can just perceive a second reflection, is then used to determine the target area boundary.

[0029] The minimum brightness value is also understood to be a threshold value that correlates with the stripe width, whereby the threshold value represents the minimum stripe width that can still be detected as a reflection in the interior by means of the camera unit.

[0030] Both the first test sequence and the second test sequence are vehicle-specific and primarily influenced by the respective interior and its reflection. For example, a light-colored (e.g., white, cream, or taupe) fabric, covering, foil, or plastic on the instrument panel will produce a different first reflection in the interior than a dark (e.g., black or blue) fabric, covering, foil, or plastic on the instrument panel. The same applies to structured surfaces in the target area or the fabrics and colors of the interior, which produce the first reflection. The strip width of the test strips can also vary for different instrument panels.The calibration procedure is therefore not limited to specific surfaces or a specific color, but can be carried out flexibly in any vehicle in order to produce the most optimal projection on the target surface.

[0031] The second test images, which are used to determine the at least one target area boundary of the target area, now have a stripe which shows the stripe width which leads to a minimum brightness in the interior and the brightness or colour which leads to a maximum brightness in the interior of the motor vehicle.

[0032] The target area corresponds to a vehicle-specific area onto which information or patterns can be projected. Determining at least one target area boundary leads to improved projection with increased projection sharpness.

[0033] The calibration process allows for easy, automated tolerance compensation, reducing time and costs while simultaneously increasing calibration accuracy.

[0034] In the second test images, only the position of the stripe is shifted. These positions can overlap, be adjacent, or spaced apart from one test image to the next.

[0035] Within the scope of the invention, it may be advantageous that the determination of the target area boundary of the target area is carried out on a first side of the target area and a second side of the target area, wherein the second side is parallel or substantially parallel to the first side.

[0036] For this purpose, the target area boundary of the target area is determined on two sides. For this purpose, it is advisable to first determine a first side of the target area boundary and additionally determine a second side of the target area, with the first side and the second side being parallel or arranged in parallel. Essentially parallel to each other means that the second side has a deviation from the first side in the range of 0.1° to 5°, preferably 0.2° to 4°, more preferably 0.3° to 3°.

[0037] This leads to a more precise definition of the target area and thus to an optimized projection of an image sequence onto the target area. This is advantageous when the target area on the vehicle's instrument panel is uneven. The projection area can be limited to the target area on two sides.

[0038] Within the scope of the invention, it is conceivable that the determination of the target area boundary of the target area is carried out on a third side of the target area and a fourth side of the target area, wherein the third side is parallel or substantially parallel to the fourth side, wherein the third side and the fourth side are arranged orthogonally or substantially orthogonally to the first side and the second side.

[0039] Additionally, it is conceivable for the target area boundary to be implemented on a third side of the target area and a fourth side of the target area. The third side and the fourth side are arranged parallel or substantially parallel to each other. Substantially parallel to each other means that the fourth side has a deviation from the third side in the range of 0.1° to 5°, preferably 0.2° to 4°, more preferably 0.3° to 3°.

[0040] However, the third side and the fourth side are then arranged orthogonally or substantially orthogonally to the first side and the second side. Substantially orthogonal is understood here to mean that the third side and / or the fourth side form an angle of 85° to 95°, preferably 86° to 94°, more preferably 87° to 93°, to the first side and / or the second side.

[0041] This also increases the accuracy of the target area definition. This is particularly advantageous for target areas that deviate from a rectangular shape. As soon as an unevenness is present, it is definitely advantageous to define the target area on the third and fourth sides. Within the scope of the invention, it can be provided that the strip width of the test strips is changed in steps from a maximum strip width to a minimum strip width, with the strip width being halved, preferably divided by a third, and more preferably quartered, from one step to the next.

[0042] This allows the stripe width with the minimum brightness in the second reflection to be determined in defined steps.

[0043] If, in an advanced calibration procedure, a stripe width of one brightness is detected and then no brightness is detected when the stripe width is subsequently halved, the last detected brightness can be used as the minimum brightness. However, it is also conceivable to vary the degree of reduction between these two stripe widths to determine the stripe width that results in a minimum brightness.

[0044] This results in an accurate and optimal strip width for determining the area boundary of the target area.

[0045] It is also conceivable that the motor vehicle is placed in a darkened room before the first test sequence is carried out.

[0046] This darkened room can, for example, be located at the end of the production line. The darkness in this room during the calibration process reduces the scattered light in the first and second reflections caused by ambient light sources. By placing the vehicle in a dark room, only the reflections of the test images or test strips projected onto the projection surface are reflected by the vehicle's interior and perceived by the camera unit. This allows the sharpness of the subsequently projected patterns or objects, or their color fidelity, to be optimally displayed when projected onto the target surface, depending on the respective interior properties.

[0047] It is also conceivable that all of the vehicle's light sources be deactivated before executing the first test sequence. Turning off the vehicle's light sources, i.e., deactivating the interior lighting or warning displays, further reduces stray light in the vehicle. This also prevents internal stray light, and only the reflections of the test images or test strips projected onto the projection surface are reflected by the interior of the vehicle and perceived by the camera unit. This further optimizes the detection of maximum and minimum brightness.

[0048] It is conceivable that a calculation unit of the control unit calculates the deviation of the projection of the projection unit from the determined at least one target area boundary of the target area, and wherein the boundary unit limits the size of the projection on the basis of the deviation, in particular scales or crops it.

[0049] The limiting unit can therefore specify how the enlarged projection area is handled depending on the projection. It is also conceivable that the limiting unit will decide whether the projection is scaled or limited depending on the calculated deviation.

[0050] Within the scope of the invention, it is optionally possible to use a camera unit in the interior of the motor vehicle or an external camera unit.

[0051] The camera unit for capturing the first reflection and the second reflection can advantageously already be located in the interior of the motor vehicle, although this camera unit can also be used for other functions. For example, the camera unit can be used to detect occupants. Alternatively, it is possible to use an external camera unit to determine the maximum brightness of the first reflection and the minimum brightness of the second reflection, whereby this can be positioned, for example, in the darkened room. An external camera unit allows the use of a camera with greater light sensitivity, so that even low brightness levels or differences in the first reflection or the second reflection can be detected.A second aspect of the invention is a calibration system according to the invention for carrying out the calibration method according to one of the preceding claims, comprising a projection unit for projecting an image sequence and / or the first test images and / or the test strips and / or the second test images, a camera unit for capturing the first reflection and the second reflection and the third reflection, a control unit for regulating and / or controlling the calibration system, wherein the control unit has a determination unit for determining the maximum brightness of the first reflection and the minimum brightness of the second reflection and the assignment of the maximum brightness to a brightness of the first test images and the minimum brightness to a strip width of the test strips and a limitation unit for limiting the second test images of the projection unit to the at least one target area boundary of the target area.

[0052] Using this calibration system, a projection surface can be limited to a target surface in an automated process, the calibration process described above.

[0053] With regard to the present invention, it is conceivable that the control unit has a calculation unit for calculating a deviation of the projection of the projection unit from the determined at least one target area boundary of the target area.

[0054] Using the calculated deviation, you can then determine whether the projection area is scaled or limited, for example, cropped.

[0055] Further advantages, features, and details of the invention will become apparent from the following description, which describes several embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.

[0056] A calibration method and a calibration system according to the invention are explained in more detail below with reference to the accompanying drawings. They each show schematically: Figure 1 shows a perspective view of a calibration system;

[0057] Figure 2 shows a schematic representation of a calibration procedure;

[0058] Figure 3 shows a schematic representation of a first projection of a first

[0059] test image in a first test sequence;

[0060] Figure 4 shows a schematic representation of a second projection of a first test image m in a first test sequence;

[0061] Figure 5 shows a schematic representation of a first projection of a test strip in a second test sequence;

[0062] Figure 6 shows a schematic representation of a second projection of a test strip in a second test sequence;

[0063] Figure 7 shows a schematic representation of a first projection of a second test image when determining the target area boundary;

[0064] Figure 8 shows a schematic representation of a second projection of a second test image when determining the target area boundary.

[0065] Elements with the same function and mode of operation are provided with the same reference numerals in Figs. 1 to 8.

[0066] Fig. 1 schematically illustrates the calibration system 50. The calibration system 50 for executing 110 the calibration method 100 of any of Figs. 2 to 8 comprises a projection unit 18 for projecting 120 an image sequence and / or the first test images 20 and / or the test strips 34 and / or the second test images 36, a camera unit 28 for capturing 130 the first reflection 24 and the second reflection 35 and the third reflection 38. Here, the camera unit 28 is arranged in the interior 26 of the motor vehicle 16.Furthermore, a control unit 32 is provided for regulating and / or controlling the calibration system 50, wherein the control unit 32 has a determination unit 30 for determining 140 the maximum brightness of the first reflection 24 and the minimum brightness of the second reflection 35 and the assignment of the maximum brightness to a brightness of the first test images 20 and the minimum brightness to a strip width SB of the test strips 34 and a limitation unit 54 for limiting the second test images 36 of the projection unit 18 to the at least one target area boundary 40 of the target area 12.

[0067] In addition, the control unit 32 has a calculation unit 52 for calculating a deviation of the projection 10 of the projection unit 18 from the determined 140 of at least one target area boundary 40 of the target area 12.

[0068] In Fig. 1, it can also be seen that the area of ​​the projection 10 by the projection unit 18 differs from the area captured by the camera unit 28. The camera unit 28 captures the reflections of the first test images 20, the test strips 34, and the second test images 36 from the interior 26 without capturing the projection surface 22.

[0069] Figs. 2 to 8 illustrate the calibration method 100 for calibrating a projection 10 of an image sequence onto a target surface 12 of an instrument panel 14 of a motor vehicle 16 using a projection unit 18 of the motor vehicle 16. Figs. 3 to 8 illustrate individual situations of the first test sequence, the second test sequence, and the determination of the target surface boundary 40 of the target surface 12. For clarity, Figs. 3 to 8 focus on the effects and omit the depiction of individual executing units.

[0070] First, a first test sequence is executed 110. The first test sequence comprises the following steps:

[0071] Projecting 120 of at least two first test images 20, see Figs. 3 and 4, by means of the projection unit 18 onto a projection surface 22 of the instrument panel 14, wherein the two first test images 20 are projected over the entire area onto the projection surface 22, wherein the first test images 20 are projected 120 one after the other, wherein each test image is assigned a brightness;

[0072] Capturing 130 a first reflection 24 for each projected 120 first test image in the interior 26 of the motor vehicle 16 during the execution of the first test sequence by means of a camera unit 28,

[0073] Determining 140 a maximum brightness in the interior 26 in one of the first reflections and assigning the maximum brightness to the brightness of one of the first test images 20 for use as brightness in a second test sequence by means of a determination unit 30 of a control unit 32,

[0074] The different hatching of the projection 10 on the projection surface 22 in Figs. 3 and 4 represents the different brightness of the projection 10. In this case, each hatching corresponds to a different color of the light from the light source. Furthermore, it is shown that the hatching in the interior space 26 is somewhat weaker, resulting from the scattering of the light. The maximum brightness of the first reflections thus differs in its luminous intensity from the brightness of the projection 10 itself.

[0075] In this case, the determination unit 30 has determined 140 that the first reflection 24 of Fig. 3 has the maximum brightness. Accordingly, the second test sequence is performed using the color or hatching of Fig. 3.

[0076] In the second test sequence, see Fig. 2, 5 and 6, the following steps are carried out 150:

[0077] Projecting 160 of at least two test strips 34 with different strip widths SB by means of the projection unit 18 onto a projection surface 22 of the instrument panel 14, wherein the test strips 34 are projected 160 one after the other,

[0078] Capturing 170 a second reflection for each projected 120 test strips 34 in the interior 26 of the motor vehicle 16 during the second test sequence by means of the camera unit 28,

[0079] Determining 180 a minimum brightness in the interior 26 in one of the second reflections and assigning the minimum brightness to the strip width SB of one of the test strips 34 for use as strip width SB for determining the target area boundary 40 by means of the determination unit 30 of the

[0080] Control Unit 32

[0081] For the test strip 34 with the strip width SB of Fig. 6, the minimum brightness in the interior 26 was determined 180. With this strip width SB, the at least one target area boundary 40 of the target area 12 is then determined.

[0082] Determining 190 at least one target area boundary 40 of the target area 12, see Fig. 2, 7 and 8, by the following steps:

[0083] Projecting 200 of at least two, preferably at least three, more preferably at least four, second test images 36 by means of the projection unit 18 onto the projection surface 22, wherein the second test images 36 are projected 200 one after the other, wherein the second test images 36 each have a stripe with the stripe width SB with the minimum brightness of the second reflection in the edge region,

[0084] Capturing 210 a third reflection 38 of the second test images 36 in the interior 26 by means of the camera unit 28,

[0085] Determining 220 the target area boundary 40 of the target area 12 by means of the determination unit 30 of the control unit 32 when the camera unit 28 detects 210 a third reflection 38.

[0086] It can be seen in Figs. 7 and 8 that the stripe in the two test images occupies different positions on the projection surface 22. The stripe of the second test image 36 in Fig. 7 is detected by the camera unit 28 as a third reflection 38. However, the stripe of the second test image 36 in Fig. 8 is no longer detected as a third reflection 38. Rather, the camera unit 28 detects darkness in the interior 26, which is represented by the missing hatching in the interior 26.

[0087] Accordingly, the boundary or area between the positions of the stripes of the second test images 36 of Figs. 7 and 8 corresponds to the target area boundary 40.

[0088] Since the target area boundary 40 is known, the second test images 36 of the projection unit 18 are limited 230 to the at least one target area boundary 40 of the target area 12 by means of a limitation unit 54 of the control unit 32 for carrying out the calibration of the target area 12.

[0089] As can be seen in Figs. 3 to 8, the projection surface 22 protrudes from the target surface 12 or has a deviation on several sides. The determination of the target surface boundary 40 on a first side 42 of the target surface 12 has already been described above. For improved adaptation of the projection surface 22 to the target surface 12, the target surface boundary 40 of the target surface 12 is additionally implemented on a second side 44 of the target surface 12, wherein the second side 44 is parallel or substantially parallel to the first side 42. For this purpose, the strips of the second test images 36 are arranged on the opposite side.

[0090] In addition, target area boundary 40 of target area 12 is determined 190 on a third side 46 of target area 12 and a fourth side 48 of target area 12, wherein the third side 46 is parallel or substantially parallel to the fourth side 48, wherein the third side 46 and the fourth side 48 are arranged orthogonally or substantially orthogonally to the first side 42 and the second side 44. For this purpose, the strips of the second test images 36 are rotated by 90° so that they are arranged orthogonally to the test strips 34 of the second test images 36 for determining the target area boundary 40 of the first side 42 and the second side 44.

[0091] As shown in Figs. 5 and 6, different strip widths SB are used for the test strips 34. The strip width SB of the test strips 34 is changed step by step from a maximum strip width SB, Fig. 5, to a minimum strip width SB, Fig. 6, with the strip width SB being halved from one step to the next. The intermediate steps are not shown here.

[0092] To achieve optimal calibration, the motor vehicle was placed in a darkened room before executing 110 the first test sequence and, in addition, all light sources of the motor vehicle 16 were deactivated 250.

[0093] To limit the projection surface 22 to the target surface 12, the calculation unit 52 of the control unit 32 calculates the deviation of the projection 10 of the projection unit 18 from the determined 140 of at least one target surface boundary 40 of the target surface 12. Whereupon the limitation unit 54, on the basis of the deviation, limits the projection 10 in size to the size of the target surface and crops it as shown in Fig. 8.

[0094] List of reference symbols

[0095] 10 Projection

[0096] 12 Target area

[0097] 14 Instrument panel

[0098] 16 motor vehicles

[0099] 18 Projection unit

[0100] 20 first test images

[0101] 22 projection screen

[0102] 24 first reflection

[0103] 26 Interior

[0104] 28 Camera unit

[0105] 30 Investigation Unit

[0106] 32 Control unit

[0107] 34 test strips

[0108] 35 second reflection

[0109] 36 second test images

[0110] 38 third reflection

[0111] 40 Target area limitation

[0112] 42 first page

[0113] 44 second page

[0114] 46 third page

[0115] 48 fourth page

[0116] 50 Calibration system

[0117] 52 Calculation unit

[0118] 54 Boundary unit

[0119] 100 calibration procedures

[0120] 110 Execute

[0121] 120 Projecting

[0122] 130 Capture

[0123] 140 Determine 150 Execute

[0124] 160 Projecting

[0125] 170 Capture

[0126] 180 Investigate

[0127] 190 Determine

[0128] 200 Project

[0129] 210 Capture

[0130] 220 Investigate

[0131] 230 Limit

[0132] 240 Place

[0133] 250 Deactivate

[0134] SB strip width

Claims

Patent claims 1 . Calibration method (100) for calibrating a projection (10) of an image sequence onto a target surface (12) of an instrument panel (14) of a motor vehicle (16) by means of a projection unit (18) of the motor vehicle (16), comprising the following steps: - Executing (110) a first test sequence by the following steps: o Projecting (120) at least two, preferably at least three, more preferably at least four, first test images (20) by means of the projection unit (18) onto a projection surface (22) of the instrument panel (14), wherein the at least two first test images (20) are projected (120) over the entire surface of the projection surface (22), wherein the first test images (20) are projected (120) one after the other, wherein a brightness is assigned to each test image, o Capturing (130) a first reflection (24) for each projected (120) first test image (20) in an interior (26) of the motor vehicle (16) during the execution of the first test sequence by means of a camera unit (28),o determining (140) a maximum brightness in the interior (26) in one of the first reflections (24) and assigning the maximum brightness to the brightness of one of the first test images (20) for use as brightness in a second test sequence by means of a determination unit (30) of a control unit (32), - Executing (150) the second test sequence by the following steps: o Projecting (160) at least two, preferably at least three, more preferably at least four, test strips (34) with different strip widths (SB) by means of the projection unit (18) onto a projection surface (22) of the instrument panel (14), wherein the test strips (34) are projected (160) one after the other, o Capturing (170) a second reflection (35) for each projected (120) test strip (34) in the interior (26) of the motor vehicle (16) during the second test sequence by means of the camera unit (28), o Determining (180) a minimum brightness in the interior (26) in one of the second reflections (35) and assigning the minimum brightness to the strip width (SB) of one of the test strips (34) for use as the strip width (SB) for determining the target area boundary (40) by means of the determination unit (30) of the control unit (32), - Determining (190) at least one target area boundary (40) of the target area (12) by the following steps: o Projecting (200) at least two, preferably at least three, more preferably at least four, second test images (36) by means of the projection unit (18) onto the projection surface (22), wherein the second test images (36) are projected (200) one after the other, wherein the second test images (36) each have a stripe in the edge region with the stripe width (SB) with the minimum brightness of the second reflection (35), o Capturing (210) a third reflection (38) of the second test images (36) in the interior (26) by means of the camera unit (28), o Determining (220) the target area boundary (40) of the target area (12) by means of the determination unit (30) of the control unit (32) when the camera unit (28) detects (210) a third reflection (38), - Limiting (230) the second test images (36) of the projection unit (18) to the at least one target area boundary (40) of the target area (12) by means of a boundary unit (54) of the control unit (32) for carrying out the calibration of the target area (12).

2. Calibration method (100) according to claim 1, characterized in that the determination (190) of the target surface boundary (40) of the target surface (12) is carried out on a first side (42) of the target surface (12) and a second side (44) of the target surface (12), wherein the second side (44) is parallel or substantially parallel to the first side (42).

3. Calibration method (100) according to claim 2, characterized in that the determination (190) of the target area boundary (40) of the target area (12) on a third side (46) of the target surface (12) and a fourth side (48) of the target surface (12), wherein the third side (46) is parallel or substantially parallel to the fourth side (48), wherein the third side (46) and the fourth side (48) are arranged orthogonally or substantially orthogonally to the first side (42) and the second side (44).

4. Calibration method (100) according to at least one of the preceding claims, characterized in that the strip width (SB) of the test strips (34) is changed step by step from a maximum strip width (SB) to a minimum strip width (SB), wherein the strip width (SB) is halved, preferably thirded, more preferably quartered, from one step to the next.

5. Calibration method (100) according to at least one of the preceding claims, characterized in that the motor vehicle is placed (240) in a darkened room before carrying out (110) the first test sequence.

6. Calibration method (100) according to at least one of the preceding claims, characterized in that before executing (110) the first test sequence, all light sources of the motor vehicle (16) are deactivated (250).

7. Calibration method (100) according to at least one of the preceding claims, characterized in that a calculation unit (52) of the control unit (32) calculates the deviation of the projection (10) of the projection unit (18) from the determined (140) at least one target area boundary (40) of the target area (12), and wherein the boundary unit (54) on the basis of the deviation, the projection (10) limited in size, in particular scaled or cropped.

8. Calibration method (100) according to at least one of the preceding claims, characterized in that a camera unit (28) in the interior (26) of the motor vehicle (16) or an external camera unit (28) is used.

9. Calibration system (50) for carrying out (110) the calibration method (100) according to one of the preceding claims, comprising a projection unit (18) for projecting (120) an image sequence and / or the first test images (20) and / or the test strips (34) and / or the second test images (36), a camera unit (28) for capturing (130) the first reflection (24) and the second reflection (35) and the third reflection (38), a control unit (32) for regulating and / or controlling the calibration system (50),wherein the control unit (32) has a determination unit (30) for determining (140) the maximum brightness of the first reflection (24) and the minimum brightness of the second reflection and the assignment of the maximum brightness to a brightness of the first test images (20) and the minimum brightness to a strip width (SB) of the test strips (34), and a limitation unit (54) for limiting the second test images (36) of the projection unit (18) to the at least one target area boundary (40) of the target area (12).

10. Calibration system (50) according to claim 9, characterized in that the control unit (32) has a calculation unit (52) for calculating a deviation of the projection (10) of the projection unit (18) from the determined (140) at least one target surface boundary (40) of the target surface (12).

Images