System, vehicle and method for online calibration of a camera on a vehicle
AssigneeApplication Solutions (Electronics and Vision) Ltd.
InventorsPeter Bone, Pantelis Ermilios, Peter Gagnon, Dave Wibberley
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Abstract
A camera mounted on or for a vehicle has camera rotational parameters φ, θ, ψ and camera translational parameters xc, yc, zc in a camera image coordinate system, and the vehicle has a vehicle coordinate system. A method for online or on-the-fly calibration of the camera involves two independent steps, namely while the vehicle is moving relative to the ground, calibrating the camera rotational parameters using a parallel geometrical calibration process, and calibrating at least some of the camera translational parameters xc, yc independently of the camera rotational parameters.
Claims14
A method for calibration of a camera on a vehicle driving on a ground in an environment, wherein camera rotational parameters and camera translational parameters are defined in a camera image coordinate system for the camera, wherein a vehicle coordinate system is defined for the vehicle, and wherein the method comprises steps:
- while moving the vehicle relative to the ground, calibrating the camera rotational parameters using a parallel geometrical calibration process,
- determining that the vehicle is moving along a curved path, and
- while the vehicle is moving along the curved path, calibrating at least selected ones of the camera translational parameters independently of the camera rotational parameters, wherein the calibrating of the selected camera translational parameters comprises the calibrating steps:
- tracking at least two features of the environment in at least two successive images captured by the camera over a period of time,
- mapping the at least two features to a ground plane,
- fitting an arc to the at least two features mapped to the ground plane,
- calculating a first vehicle turning center in the camera image coordinate system from the arc,
- determining a vehicle steering angle,
- calculating a second vehicle turning center in the vehicle coordinate system from the vehicle steering angle,
- determining a difference between the first vehicle turning center in the camera image coordinate system and the second vehicle turning center in the vehicle coordinate system,
- determining, from the difference, an offset to be applied to the selected camera translational parameters so that a position of the first vehicle turning center in the camera image coordinate system will correspond to the position of the second vehicle turning center in the vehicle coordinate system, and
- applying the offset to the selected camera translational parameters.
A method of calibrating a camera on a vehicle, wherein a vehicle coordinate system is defined relative to the vehicle, wherein a longitudinal translational parameter, a transverse translational parameter and rotational parameters are defined in a camera image coordinate system for the camera, and the method comprises steps:
- a) while the vehicle is moving, obtaining first image data from the camera;
- b) evaluating the first image data and performing a parallel geometrical calibration process based thereon, to thereby calibrate the rotational parameters of the camera to the vehicle coordinate system;
- c) while the vehicle is moving along a curved path, obtaining second image data from the camera;
- and
- d) evaluating the second image data and performing a separate calibration process based thereon, to thereby calibrate the longitudinal translational parameter and the transverse translational parameter of the camera to the vehicle coordinate system, wherein the separate calibration process is performed separately and independently of the parallel geometrical calibration process and separately and independently of the rotational parameters, and wherein the separate calibration process for calibrating the longitudinal and transverse translational parameters comprises the calibrating steps:
- tracking at least two environment features in at least two successive images of the second image data,
- mapping the at least two environment features to a ground plane,
- fitting an arc to the at least two environment features mapped to the ground plane,
- calculating a first turning center of the vehicle in the camera image coordinate system from the arc,
- determining a steering angle of the vehicle,
- calculating a second turning center of the vehicle in the vehicle coordinate system from the steering angle,
- determining a difference between the first turning center in the camera image coordinate system and the second turning center in the vehicle coordinate system,
- determining, from the difference, an offset to be applied to the longitudinal and transverse translational parameters so that a position of the first turning center in the camera image coordinate system will correspond to the position of the second turning center in the vehicle coordinate system, and
- applying the offset to the longitudinal and transverse translational parameters.
Dependencies are inferred from the claim text.