Alexander Würz-Wessel

In-factory calibration of multiocular camera systems

A complete framework for automatic calibration of camera systems with an arbitrary number of image sensors is presented. This new approach is superior to other methods in that it obtains both the internal and external parameters of camera systems with arbitrary resolutions, focal lengths, pixel sizes, positions and orientations from calibration rigs printed on paper. The only requirement on the placement of the cameras is an overlapping field of view. Although the basic algorithms are suitable for a very wide range of camera models (including OmniView and fish eye lenses) we concentrate on the camera model by Bouguet (http://www.vision.caltech.edu/bouguetj/). The most important part of the calibration process is the search for the calibration rig, a checkerboard. Our approach is based on the topological analysis of the corner candidates. It is suitable for a wide range of sensors, including OmniView cameras, which is demonstrated by finding the rig in images of such a camera. The internal calibration of each camera is performed as proposed by Bouguet, although this may be replaced with a different model. The calibration of all cameras into a common coordinate system is an optimization process on the spatial coordinates of the calibration rig. This approach shows significant advantages compared to the method of Bouguet, esp. for cameras with a large field of view. A comparison of our automatic system with the camera calibration toolbox for MATLAB, which contains an implementation of the Bouguet calibration, shows its increased accuracy compared to the manual approach.