US 2017/0287166 A1 · CAMERA CALIBRATION METHOD USING A CALIBRATION TARGET

Abstract

Calibration methods use a calibration target for obtaining the intrinsic and extrinsic camera parameters of one or more cameras are. The methods can include acquiring, with each camera, a sequence of target images representing the calibration target in different target poses and at different acquisition times. The methods can include identifying reference images from the target images, and defining volume bins, angle bins and multi-camera bins into which the reference images are stored. The reference images can be used to determine the intrinsic and extrinsic parameters of the one or more cameras. In some implementations, the calibration methods can enable a user to monitor the progress of the calibration process, for example by providing an interactive calibration target including an input/output user interface to guide the user in real-time during the acquisition of the target images and/or sensors to provide positional information about the target poses.

Claims26

Dependent claims

A method for intrinsic calibration of a camera using a calibration target, the camera having a field of view covering a scene, the method comprising the steps of:

providing a plurality of target images acquired with the camera, each target image representing a view of the calibration target in a respective one of a plurality of target poses, each target pose corresponding to a certain location and orientation of the calibration target relative to the camera;
partitioning a volume of interest of the scene into a set of volume bins;
defining a set of angle bins, each angle bin encompassing a respective range of possible orientation values for the calibration target;
identifying, among the plurality of target images, reference images of the calibration target;
assigning each reference image to either or both of one of the volume bins and one of the angle bins based on the respective target pose corresponding to the reference image;
and
obtaining intrinsic camera parameters based on the reference images.

4 more elements

A method for extrinsic calibration of a network of cameras using a calibration target, each camera of the network having a field of view that covers a portion of a scene and partially overlaps the field of view of at least another camera of the network, the method comprising the steps of:

providing, for each camera, a plurality of target images acquired with the camera, each target image representing a view of the calibration target in a respective one of a plurality of target poses and at a respective one of a plurality of acquisition times;
defining at least one multi-camera bin, each multi-camera bin being associated with two or more of the cameras of the network, the two or more cameras having partially overlapping fields of view;
identifying, for each camera, qualified target images among the plurality of target images;
for each multi-camera bin:
assigning sets of multi-camera reference images to the multi-camera bin, the multi-camera reference images in each set having a same acquisition time and consisting of one of the qualified target images acquired by each one of the two or more associated cameras;
and
obtaining, for each one of the two or more associated cameras and based on the multi-camera reference images, estimates of extrinsic camera parameters in a bin reference frame associated with the multi-camera bin;
and
if the at least one multi-camera bin consists of more than one multi-camera bin, obtaining, for each camera of the network and based on the estimates of the extrinsic camera parameters obtained for every camera of the network, calibrated values of the extrinsic camera parameters in a same global reference frame;
otherwise, using, for each camera of the network, the estimates of the extrinsic camera parameters as the calibrated values of the extrinsic camera parameters.

7 more elements

Dependencies are inferred from the claim text.

Camera calibration method using a calibration target

Life of this patent

Camera calibration method using a calibration target

Life of this patent

Abstract

Claims26