2015 年 81 巻 2 号 p. 164-169
There is a need for precise extrinsic parameters of vehicle mounted cameras in order to provide a good overhead view image to the driver. In this paper, we propose a simultaneous estimation of the extrinsic parameters of multiple fish-eye cameras using simple calibration targets. The proposed method estimates the parameters directly from the fish-eye images, giving more accurate results in comparison with a previous method that uses perspective projection converted images. Moreover, this method allows parameter estimation by simply arranging calibration targets anywhere around the vehicle. We conducted two experiments to quantitatively evaluate the estimation accuracy of the proposed method. In each experiment, two cases have been considered. In one case (the known case), targets' position were known beforehand. In the other case (the unknown case), targets' positions were unknown beforehand. In each experiment, the estimation error for the unknown case was 4-5 times bigger than the known case. In a simulation experiment, we compared the estimation accuracy of different target shapes, in order to identify the optimal shape of the target. The cubic shape turned out to be the most appropriate.