Abstract: The present invention is a method for presenting the fisheye-camera images. A calibration target with a concentric-and-symmetric pattern (PCT) is utilized to assist in parameterizing a fisheye camera (FIS) in order to ascertain the optical parameters comprising the principal point, the focal length constant and the projection function of the FIS. Hence, the position of an imaged point referring to the principal point on the image plane directly reflects its corresponding zenithal distance ? and azimuthal distance ? of the sight ray in space so as to normalize the imaged point onto a small sphere. Further according to the map projections in cartography capable of transforming the global geometry into flap maps, the interesting area in a field of view can be accordingly transformed by a proper projection method.

Abstract: The present invention is a method for exploring the viewpoint and focal length of a fisheye lens camera (FELC). It employs the characteristic of the central symmetry of the distortion of the fisheye lens (FEL) to set its optic axis by means of a calibration target with a plurality of symmetrically homocentric figures. Once the optic axis is fixed, further disclose the viewpoint (VP) of the FELC along the optic axis through a trail-and-error procedure and calculate its effective focal length and classify it to the primitive projection mode. Because the invention is capable of finding out both the internal and external parameters of the FELC and the calibration method is easy, low-cost, suitable to any projection model, and has greater sensitivity corresponding to an increasing in image distortion, the distortive images can be transformed easily to normal ones which fit in with a central perspective mechanism.