3D Camera calibration for adjustable camera settings
Described are calibration and rectification systems and methods for 3D cameras. The calibration methods described herein derive calibration parameters in real time for multiple camera settings. Calibration parameters are used to rectify stereo images as part of a process for creating 3D images, videos, and VR or AR experiences. Additionally multi-camera systems for implementing the calibration and rectification methods are disclosed. 3D camera calibration methods involving a limited number of calibration points reduce the cost and complexity of conventional calibration methods while also allowing for higher performing 3D cameras having many possible configurations of camera settings.
1. A method of calculating real time calibration parameters for a camera device having a first camera setting and a second camera setting, the method comprising: providing a library of calibration files, each calibration file associated with a unique value for the first camera setting and a unique value for the second camera setting, each calibration file further having a calibration parameter matrix including extrinsic calibration parameters for the camera device, the calibration parameter matrix further having intrinsic calibration parameters for the first and second camera modules; detecting a real time value for the first camera setting from the camera device and locating, within the library of calibration files, two calibration files associated with values for the first camera setting most proximate to the real time value for the first camera setting; detecting a real time value for the second camera setting from the camera device and locating, within the library of calibration files, two calibration files associated with values for the second camera setting most proximate to the real time value for the second camera setting; extracting the intrinsic calibration parameters and the extrinsic calibration parameters from the two calibration files associated with the first camera setting; applying an interpolation function to the intrinsic calibration parameters and receiving as an output of the interpolation function a first set of intermediate intrinsic calibration parameters for the first camera module and the second camera module having the real time value for the first camera setting; applying the interpolation function to the extrinsic calibration parameters and receiving as an output of the interpolation function a first set of intermediate extrinsic calibration parameters for the camera device having the real time value for the first camera setting; extracting the intrinsic calibration parameters and the extrinsic calibration parameters from the two calibration files associated with the second camera setting; applying the interpolation function to the intrinsic calibration parameters and receiving as an output of the interpolation function a second set of intermediate intrinsic calibration parameters for the first camera module and the second camera module having the real time value for the second camera setting; applying the interpolation function to the extrinsic calibration parameters and receiving as an output of the interpolation function a second set of intermediate extrinsic calibration parameters for the camera device having the real time value for the second camera setting; applying the interpolation function to the first set of intermediate intrinsic calibration parameters and the second set of intermediate intrinsic calibration parameters and receiving as an output of the interpolation function real time intrinsic calibration parameters for the camera device having the real time value for the first camera setting and the real time value for the second camera setting; and applying the interpolation function to the first set of intermediate extrinsic calibration parameters and the second set of intermediate extrinsic calibration parameters and receiving as an output of the interpolation function real time extrinsic calibration parameters for the camera device having the first real time value for the first camera setting and the real time value for the second camera setting.
2. The method of claim 1 wherein the extrinsic calibration parameters include a rotation matrix formed by multiplying three elemental rotation matrices, each elemental rotation matrix including trigonometric functions of an Euler angle.
3. The method of claim 2 , wherein the extrinsic calibration parameters are extracted from the two calibration files associated with the first camera setting and the two calibration files associated with the second camera setting by, within each calibration file, separating the elemental rotation matrices from the rotation matrix and deriving an x dimension Euler angle from an x dimension elemental rotation matrix, deriving a y dimension Euler angle from an y dimension elemental rotation matrix, and a z dimension Euler angle from a z dimension elemental rotation matrix.