Camera Calibration Using Two Concentric Circles

We present a simple calibration method for computing the extrinsic parameters (pose) and intrinsic parameters (focal length and principal point) of a camera by imaging a pattern of known geometry. Usually, the patterns used in calibration algorithms are complex to build (three orthogonal planes) or need a lot of features (checkerboard-like pattern). We propose using just two concentric circles that, when projected onto the image, become two ellipses. With a simple mark close to the outer circle, our algorithm can recover the full pose of the camera. Under the perfect pinhole camera assumption, the pose and the focal length can be recovered from just one image. If the principal point of the camera has to be computed as well, two images are required. We present several results, using both synthetic and real images, that show the robustness of our method.

• Type: Conference
• Year: 2004
• Where: ICIAR
• Authors: Francisco Abad, Emilio Camahort, Roberto Vivó
• Keywords: Focal Length, ICIAR 2004, Principal Point, Simple Calibration Method