DE102013002375A1 - Method for calibrating camera of motor car in parking aid, involves detecting reference object in image using camera, and processing image, in order to recognize parameter stored in reference pattern of camera - Google Patents

Abstract

The method involves providing a reference object (3) in the environment of a motor car (1), such that the reference object is provided with a reference pattern. The reference object is detected in an image using a camera (4). The image is processed, in order to recognize a parameter stored in the reference pattern of the camera. The parameter is saved. The height of camera in the motor car, a distance (5) to front axle (6) of the motor car or a calibration value of the reference object is stored as a parameter. Independent claims are included for the following: (1) the motor car; and (2) a computer program product comprising computer-readable storage medium storing program for calibrating camera of motor car.

Description

The invention relates to a method for calibrating a camera of a motor vehicle.

Cameras, such as front cameras, are increasingly used in motor vehicles to capture relevant information in advance of the motor vehicle, which are transmitted to one or more electronic assistance systems to improve road safety. These include, for example, lane departure warning systems, brake assistants, driving light assistants or the like. The front camera is usually arranged in the upper region of the windshield and continuously captures images of the surroundings in advance of the motor vehicle.

In the production of motor vehicles, the front camera is calibrated in a final step before the end of production. For this purpose, usually two reference objects (also called reference targets or targets in the English language) are arranged at a distance from each other at a predetermined distance from the camera, wherein subsequently images of the camera are recorded in order to carry out the calibration process. For a functioning calibration, some parameters are needed, such as the distance of the reference objects to each other, the distance to the vehicle and the height of the reference objects in comparison to the motor vehicle or the front camera. These parameters are read into the camera before the actual calibration process.

From the DE 10 2010 062 696 A1 For example, a method for adjusting and / or calibrating an environmental sensor in a vehicle is known. It comprises the steps of attaching a wheel target to a wheel, taking a picture of the wheel target by a measuring unit, determining the spatial orientation of the vehicle from the image of the wheel target, placing a calibration board with a calibration board target, picking up a wheel target Image of the target, determining the position of the calibration panel, capturing an image of the calibration panel with the environmental sensor, and determining the spatial orientation of the environmental sensor with respect to the calibration panel and the vehicle.

An object of the invention is to provide a method for calibrating a camera of a motor vehicle, which allows a simple and reliable calibration, without reading parameters into the camera before the actual calibration process.

This object is solved by the features of patent claim 1. Further advantageous embodiments of the invention are each the subject of the dependent claims. These can be combined in a technologically meaningful way. The description, in particular in conjunction with the drawing, additionally characterizes and specifies the invention.

• – Bereitstellen eines Referenzobjekts vor der Kamera des Kraftfahrzeugs, wobei das Referenzobjekt ein Referenzmuster umfasst;
• – Erfassen des Referenzobjekts mit der Kamera in einem Bild;
• – Verarbeitung des Bildes, um wenigstens einen Parameter der Kamera zu erkennen, der im Referenzmuster hinterlegt ist; und
• – Speichern des Parameters.

Accordingly, a method is provided for calibrating a camera of a motor vehicle, in which the following steps are carried out:

• - Providing a reference object in front of the camera of the motor vehicle, wherein the reference object comprises a reference pattern;
• - Capturing the reference object with the camera in an image;
• Processing the image to detect at least one parameter of the camera deposited in the reference pattern; and
• - Save the parameter.

Accordingly, it is possible to provide a parameter for the camera without the prior reading of calibration data, which is then stored for future use after completion of production. Accordingly, the calibration of the camera in many production facilities can proceed in the same way since factory-specific calibration data are now stored in the reference pattern without having to provide a large number of different files. This simplifies calibration of the camera and thus reduces costs. As a camera, both front cameras, such as those used in vehicle assistants, or rear cameras of a parking aid can be used.

In one embodiment, a height of the camera in the motor vehicle, a distance to a front axle of the motor vehicle or a calibration value of the reference object is stored as a parameter.

These parameters represent typical calibration data that is unique to both the vehicle and the manufacturing facilities.

In a further embodiment, the reference pattern is designed as a text field.

A text box is an easy way to set a parameter for calibrating the camera in the reference pattern. The determination of the parameter can be carried out with a suitable image recognition software.

In another embodiment, the text field includes an identifier of the parameter and a value of the parameter.

Thus, it is possible to determine the parameter and assign a value to it. This is particularly advantageous if several Parameters in the reference pattern are stored on the reference object.

In a further embodiment, the reference pattern is formed as a symbol.

A symbol represents another possibility to deposit a parameter for the calibration of the camera in the reference pattern. The determination of the parameter can be carried out with a suitable image recognition software.

In a further embodiment, the shape of the symbol represents an identification of the parameter and the size of the symbol represents a value of the parameter.

Thus, it is possible to determine the parameter via the shape of the symbol and to assign a value to it via the size of the symbol, for example the area.

In another embodiment, reference pattern is formed as a character with a text field.

This embodiment combines a text box with a symbol.

In a further embodiment, the character or position of the character represents an identification of the parameter and the text field represents a value of the parameter.

Thus, it is possible to determine the parameter via the shape or arrangement of the symbol and to assign a value to it via the text field, for example a number sequence. The determination of the parameter can in turn be carried out with a suitable image recognition software.

In a further embodiment, the reference pattern is designed as a bar code.

A barcode is another way of storing a parameter for calibrating the camera in the reference pattern. The determination of the parameter can in turn be carried out with a suitable image recognition software.

In a further embodiment, the parameter is stored non-volatile in the camera or in a control unit of the camera.

In order to keep the calibration effective even after the procedure has been completed, the parameter determined by the method can be stored, for example in a non-volatile memory chip (flash memory) on the camera or the control unit assigned to the camera.

The described method and the advantageous embodiments can be provided in a motor vehicle, in particular in a control unit for a camera.

The control unit may have a digital microprocessor unit (CPU) data-connected to a memory system and a bus system, a random access memory (RAM) and a memory means. The CPU is adapted to execute instructions executed as a program stored in a memory system, to detect input signals from the data bus, and to output signals to the data bus. The storage system may have various storage media such as optical, magnetic, solid state and other non-volatile media on which a corresponding computer program for carrying out the method and the advantageous embodiments is stored. The program may be arranged to be capable of embodying the methods described herein so that the CPU may perform the steps of such methods and thereby control the camera.

Suitable for performing a method is a computer program having program code means for performing all the steps of any one of the claims when the program is run on a computer.

The computer program can be easily read into existing control units and used to regulate a calibration of a front camera.

Provided for this purpose is a computer program product with program code means, which are stored on a computer-readable data carrier in order to carry out the method according to any of the claims, when the program product is executed on a computer. The computer program product can be integrated as a retrofit option in control units.

• a) Mittel zum Bereitstellen eines Referenzobjekts vor der Kamera des Kraftfahrzeugs, wobei das Referenzobjekt ein Referenzmuster umfasst;
• b) Mittel zum Erfassen des Referenzobjekts mit der Kamera in einem Bild;
• c) Mittel zum Verarbeitung des Bildes, um wenigstens einen Parameter der Kamera zu erkennen, der im Referenzmuster hinterlegt ist; und
• d) Mittel zum Speichern des Parameters.

Another aspect of the invention relates to an apparatus for calibrating a camera of a motor vehicle, comprising:

• a) means for providing a reference object in front of the camera of the motor vehicle, wherein the reference object comprises a reference pattern;
• b) means for capturing the reference object with the camera in an image;
• c) means for processing the image to detect at least one parameter of the camera deposited in the reference pattern; and
• d) means for storing the parameter.

In one embodiment of the apparatus is a height of the camera in the motor vehicle, a Distance to a front axle of the motor vehicle or a calibration value of the reference object stored as a parameter.

In a further embodiment of the apparatus, the reference pattern is designed as a text field.

In a further embodiment of the apparatus, the text field comprises an identification of the parameter and a value of the parameter.

In a further embodiment of the apparatus, the reference pattern is formed as a symbol.

In a further embodiment of the apparatus, the shape of the symbol represents an identification of the parameter and the size of the symbol represents a value of the parameter.

In a further embodiment of the apparatus reference pattern is formed as a character with a text field.

In a further embodiment of the apparatus, the character or position of the character represents an identification of the parameter and the text field represents a value of the parameter.

In a further embodiment of the apparatus, the reference pattern is formed as a bar code.

In a further embodiment of the apparatus, the parameter is stored non-volatile in the camera or in a control unit of the camera.

Some embodiments will be explained in more detail with reference to the drawing. Show it:

1 FIG. 2: a side view of a motor vehicle when using the method according to the invention, FIG.

2 : a plan view of a motor vehicle in the application of the method according to the invention,

3 FIG. 2 shows a further plan view of a motor vehicle in the application of the method according to the invention, FIG.

4 FIG. 2 shows a further plan view of a motor vehicle in the application of the method according to the invention, FIG.

5 a further plan view of a motor vehicle in the application of the method according to the invention, and

6 : Steps of the method according to the invention in a flow chart.

In the figures, identical or functionally identical components are provided with the same reference numerals.

In 1 is a motor vehicle 1 shown in a side view. In front of the motor vehicle 1 is at a height 2 a reference object 3 arranged. The car 1 has a camera 4 on, which is suitable an image of the reference object 3 take. The camera 4 is a vehicle-typical distance 5 to a front axle 6 arranged. The camera 4 is described in this embodiment as a front camera, as used for example in vehicle assistants use. But it is also possible, the camera 4 as a rear camera to provide a parking aid, in which case the reference object 3 behind the motor vehicle 1 would be to arrange.

The camera 4 is about a connection 7 with a control unit 8th data transmitting connected. To calibrate the camera 4 becomes an image of the reference object 3 recorded and for example in the control unit 8th evaluated.

Embodiments of the reference object 3 in the application of the method according to the invention are described below with reference to the 2 to 5 described. In each case, a plan view of the motor vehicle 1 and to the reference object 3 shown. The representation thus follows a line along the points ABC, as in FIG 1 shown.

As in 2 is shown has the reference object 3 a right target 9 , a left target 10 and a reference pattern 11 on. The reference pattern 11 is in 2 between the right target 9 and the left target 10 arranged. It is also possible, the reference pattern 11 for example, above or below the right target 9 or the left target 10 to arrange.

The reference pattern 11 has several first text fields 12 . 12 ' and 12 '' on which is an identification of the parameter, for example the height of the camera 4 in the motor vehicle 1 , the distance 5 to the front axle 6 of the motor vehicle 2 or a calibration value of the reference object 3 such as the distance of the right target 9 to the left target 10 , as an alphanumeric string.

In addition, the reference pattern assigns 11 several second text fields 13 . 13 ' and 13 '' which represent a value of the parameter. The first text fields 12 . 12 ' and 12 '' and the second text boxes 13 . 13 ' and 13 '' can be captured as an image.

The taken picture of the camera 4 is about the connection 7 to a suitable image recognition software on the control unit 8th transferred and evaluated so that the parameter or parameters are now available for calibration. This eliminates the need to read calibration data.

It goes without saying that the in 2 embodiment shown by way of example only, in particular, other or a different number of parameters on the reference pattern 11 of the reference object 3 could be represented.

In 3 a further embodiment is shown. In the 3 The embodiment shown differs from that in FIG 2 in that the reference pattern 11 a first symbol 14 , a second symbol 15 and a third symbol 16 having.

The first symbol 14 , the second symbol 15 and the third symbol 16 Another option is a parameter for calibrating the camera 4 in the reference pattern 11 to deposit. The shape of the symbols 13 . 14 , and 15 represent an identification of the parameter and the size of the symbols 13 . 14 , and 15 a value of the parameter. Thus, it is possible to change the parameter via the shape of the symbols 13 . 14 , and 15 to determine and tell him about the size of the symbols 13 . 14 , and 15 For example, the area to assign a value.

In 4 a further embodiment is shown. In the 4 The embodiment shown differs from that in FIG 2 in that the reference pattern 11 character 17 . 18 and 19 includes, each with a text box 20 . 21 or 22 are executed. The arrangement of the characters 17 . 18 and 19 in the reference pattern 11 represent an identification of the parameter and the text fields 20 . 21 or 22 a value of the parameter.

In 5 a further embodiment is shown. In the 5 The embodiment shown differs from that in FIG 2 in that the reference pattern 11 as a barcode 23 is trained.

In 6 the method is again summarized in a flow chart.

In step 100 the provision of the reference object takes place 3 in the vicinity of the motor vehicle 1 , where the reference object 3 a reference pattern 11 includes. In step 102 the acquisition of the reference object takes place 3 with the camera 4 in a picture. In step 104 the image is processed by at least one parameter of the camera 4 to recognize that in the reference pattern 11 is deposited. In step 106 the parameter is saved.

Although some possible embodiments of the invention have been disclosed in the foregoing description, it is to be understood that numerous other variants of embodiments exist through the possibility of combining all of the cited and further all of the obvious technical features and embodiments. It is further understood that the embodiments are to be understood as examples only, which in no way limit the scope, applicability and configuration. Rather, the foregoing description would suggest a suitable way for the skilled person to realize at least one exemplary embodiment. It should be understood that in an exemplary embodiment, numerous changes in the function and arrangement of the elements may be made without departing from the scope and equivalents disclosed in the claims.

LIST OF REFERENCE NUMBERS

1

motor vehicle

2

height

3

reference object

4

camera

5

distance

6

front axle

7

connection

8th

control unit

9

right target

10

left target

11

reference pattern

12

first text field

12 '

first text field

12 ''

first text field

13

second text field

13 '

second text field

13 ''

second text field

14

first symbol

15

second symbol

16

third icon

17, 18, 19

character

20, 21, 22

additional text fields

23

barcode

100-106

steps

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010062696 A1 [0004]

Claims (13)

Method for calibrating a camera ( 4 ) of a motor vehicle ( 1 ), in which the following steps are performed: providing a reference object ( 3 ) in the vicinity of the motor vehicle ( 1 ), the reference object ( 3 ) a reference pattern ( 11 ); - Capture the reference object ( 3 ) with the camera ( 4 ) in a picture; Processing the image to at least one parameter of the camera ( 4 ) in the reference pattern ( 11 ) is deposited; and - saving the parameter. Method according to Claim 1, in which a height of the camera ( 4 ) in the motor vehicle ( 1 ), a distance ( 5 ) to a front axle ( 6 ) of the motor vehicle ( 1 ) or a calibration value of the reference object ( 3 ) is stored as a parameter. Method according to one of Claims 1 or 2, in which the reference pattern ( 11 ) as a text field ( 12 . 13 ) is trained. Method according to Claim 3, in which the text field ( 12 . 13 ) comprises an identification of the parameter and a value of the parameter. Method according to Claim 1 or 2, in which the reference pattern is represented as a symbol ( 14 . 15 . 16 ) is trained. Method according to Claim 5, in which the shape of the symbol ( 14 . 15 . 16 ) an identification of the parameter and the size of the symbol ( 14 . 15 . 16 ) represent a value of the parameter. Method according to Claim 1 or 2, in which the reference pattern ( 11 ) as sign ( 17 . 18 . 19 ) with a text field ( 20 . 21 . 22 ) is trained. Method according to Claim 7, in which the sign ( 17 . 18 . 19 ) or the position of the character ( 17 . 18 . 19 ) an identification of the parameter and the text field ( 20 . 21 . 22 ) represent a value of the parameter. Method according to Claim 1 or 2, in which the reference pattern ( 11 ) as a barcode ( 23 ) is trained. Method according to one of Claims 1 to 9, in which the parameter in the camera ( 4 ) or in a control unit ( 8th ) the camera ( 4 ) is stored non-volatile. Motor vehicle with a control unit ( 8th ), the control unit ( 8th ) has a memory means with a computer program stored thereon, wherein the computer program for carrying out a method according to one of claims 1 to 10 is configured. Computer program for carrying out a method according to one of Claims 1 to 10. A computer program product comprising program code means stored on a computer readable medium for carrying out the method of any of the preceding claims 1 to 10 when said program code means are executed on a computer.

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