Camera calibration is the process of computing the extrinsic and intrinsic parameters of a camera. Once you calibrate a camera, you can use the image information to recover 3-D information from 2-D images.
Fisheye camera is generally use a complex series of lenses to enlarge the camera's field of view, enabling it to capture wide panoramic or hemispherical images.
Fisheye cameras are used in odometry and to solve the simultaneous localization and mapping (SLAM) problems visually. Other applications include, surveillance systems, GoPro, virtual reality (VR) to capture 360 degree field of view (fov), and stitching algorithms.
