New calibration technique for a novel stereo camera

A novel stereo camera architecture has been proposed by some researchers recently. It consists of a single digital camera and a mirror adaptor attached in front of the camera lens. The adaptor functions like a pair of periscopes which split the incoming light to form two stereo images on the left and right half of the image sensor. This novel architecture has many advantages in terms of cost, compactness, and accuracy, relative to a conventional stereo camera system with two separate cameras. However, straightforward extension of the traditional calibration techniques were found to be inaccurate and ineffective. Therefore we present a new technique which fully exploits the physical constraint that the stereo image pair have the same intrinsic camera parameters such as focal length, principle point and pixel size. Our method involves taking one image of a calibration object and estimating one set of intrinsic parameters and two sets of extrinsic parameters corresponding to the mirror adaptor simultaneously. The method also includes lens distortion correction to improve the calibration accuracy. Experimental results on a real camera system are presented to demonstrate that the new calibration technique is accurate and robust.