Device and method for calibrating an image sensor

• US 7,574,315 B2
• Filed: 02/19/2004
• Issued: 08/11/2009
• Est. Priority Date: 04/24/2003
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Abraham, Steffen, Bothe, Hans-Dieter
• Primary Examiner(s): Nghiem; Michael P
• Application Number:
  US10/554,251
• Publication Number:
  US 20070033999A1
• Time in Patent Office: 2,000 Days
• Field of Search: 702/45, 702/50, 702/85, 702/100, 702/58, 702/104, 702/116, 702/183, 702/185, 702/94, 702/95, 340/438, 340/439, 250/252.1, 250/339.09, 250/370.01
• US Class Current: 702/85
• CPC Class Codes: B60R 21/01538 for image processing, e.g. cameras or sensor arrays
• CPC Class Codes: B60R 25/1012 Zone surveillance means, e.g. parking lots, truck depots
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration

Abstract

A device and a method are proposed for monitoring, tracking and determining at least one calibration parameter of the geometrical calibration of at least one image sensor, the at least one image sensor monitoring a scene that stays the same in parts. In one exemplary embodiment, the at least one image sensor is used for monitoring the passenger compartment of a motor vehicle.

Claims

1. A device for determining at least one calibration parameter of at least one image sensor, comprising:

the at least one image sensor, which is configured to monitor a scene of a passenger compartment of a motor vehicle in which at least a portion of the scene remains static over time; and

at least one processing unit configured to detect a decalibration of the at least one image sensor in the operation of the at least one image sensor, as a function of image signals, and to, upon detecting the decalibration, at least one of report the decalibration to at least one of a subsequent system and the driver, and determine the at least one calibration parameter as a function of the image signals;

wherein the at least one image sensor derives the image signals at least from at least one invariant pattern in an image coverage range of the at least one image sensor,

wherein the at least one invariant pattern is formed by at least one reference object applied in the scene for determining the at least one calibration parameter, and wherein the at least one reference object is applied to at least one object of the scene that is relevant with respect to a monitoring function of the at least one image sensor, wherein the at least one reference object is applied to at least one of at least one air bag flap, at least one air bag, and at least one steering wheel in the passenger compartment of the motor vehicle.

2. The device of claim 1, wherein the at least one reference object is at least one of an illumination arrangement, an infrared light-emitting diode, and is configured so that it has a high reflectivity between 0.5 and 1.0.

3. The device of claim 1, wherein the at least one reference object includes at least one of a geometrical shape, a point, a circle, a triangle, a quadrilateral, a square, at least one letter, at least one character, at least one logo.

4. The device of claim 1, wherein the at least one invariant pattern is formed by at least one naturally occurring object of the scene, wherein the at least one invariant pattern is formed by at least one object located in a design-conditioned manner in the passenger compartment of a motor vehicle.

5. A method for determining at least one calibration parameter of at least one image sensor monitoring a scene of a passenger compartment of a motor vehicle in which at least a portion of the scene remains static over time, the method comprising:

detecting a decalibration of the at least one image sensor during the operation of the at least one image sensor as a function of image signals;

upon the detection of the decalibration, at least one of reporting the decalibration to at least one of a subsequent system and the driver, and determining the at least one calibration parameter as a function of the image signals; and

deriving the image signals from at least one invariant pattern in the image coverage range of the at least one image sensor by the at least one image sensor;

wherein the image signals are at least one of derived from at least one reference object applied in the scene for the determination of at least one calibration parameter, and derived at least from at least one naturally occurring object of the scene, the at least one reference object at least one of being an illuminating arrangement and having a high reflectivity, and

wherein the image signals are derived from at least one reference object, the at least one reference object being applied to an object of the scene that is relevant with respect to the monitoring function of the at least one image sensor, wherein the at least one reference object is applied to at least one of at least one air bag flap, at least one air bag, and at least one steering wheel in the passenger compartment of the motor vehicle.

6. A computer readable medium having a computer program which is executable by a computer processor, comprising:

a computer program arrangement having computer program code for determining at least one calibration parameter of at least one image sensor monitoring a scene of a passenger compartment of a motor vehicle in which at least a portion of the scene remains static over time, by performing the following;

detecting a decalibration of the at least one image sensor during the operation of the at least one image sensor as a function of image signals;

upon the detection of the decalibration, at least one of reporting the decalibration to at least one of a subsequent system and the driver, and determining the at least one calibration parameter as a function of the image signals; and

deriving the image signals from at least one invariant pattern in the image coverage range of the at least one image sensor by the at least one image sensor;

wherein the at least one invariant pattern is formed by at least one reference object applied in the scene for determining the at least one calibration parameter, and

wherein the at least one reference object is applied to at least one object of the scene that is relevant with respect to a monitoring function of the at least one image sensor, wherein the at least one reference object is applied to at least one of at least one air bag flap, at least one air bag, and at least one steering wheel in the passenger compartment of the motor vehicle.