A method for calibrating a camera system comprising a plurality of at least four cameras (2F, 2B, 2L, 2R, 11F, 11B, 11L, 11R, 11FR, 11FL, 11BL, 11BR) having a predetermined intrinsic calibration, the cameras being provided on an object such as a vehicle and covering a surrounding perimeter of the object, comprising the steps of: for each of the plurality of cameras: (a) positioning a set of markers spaced apart by known dimensions and located on a single plane in the surrounding perimeter of the object and in the field of view (3F, 3B, 3L, 3R) of that camera; and (b) calculating extrinsic parameters of that camera from the respective set of markers for that camera; wherein for at least a first camera of the plurality of cameras, the respective set of markers comprises the origin such that the extrinsic parameters of the at least a first camera refer to the origin; and further: calculating a second set of extrinsic parameters for at least a second and a fourth camera of the plurality of cameras relative to the extrinsic parameters of the first camera obtained in step (b); wherein the second camera is a neighbouring camera of the first camera in a clockwise direction and the fourth camera is a neighbouring camera of the first camera in a counter-clockwise direction; calculating two second sets of extrinsic parameters for at least a third camera of the plurality of cameras relative to the extrinsic parameters of the first camera obtained in step (b) based on the result of step; (d) estimating a third set of extrinsic parameters for each of the plurality of cameras except the first camera relative to the origin based on the results of steps and; and (e) optimizing the sets of extrinsic parameters; wherein the optimization minimizes the error of re-projections on the set of markers which use the estimation results of step (d) and further minimizes the differences between the results of step. for each of the plurality of cameras: (a) positioning a set of markers spaced apart by known dimensions and located on a single plane in the surrounding perimeter of the object and in the field of view (3F, 3B, 3L, 3R) of that camera; and (b) calculating extrinsic parameters of that camera from the respective set of markers for that camera; wherein for at least a first camera of the plurality of cameras, the respective set of markers comprises the origin such that the extrinsic parameters of the at least a first camera refer to the origin; (a) positioning a set of markers spaced apart by known dimensions and located on a single plane in the surrounding perimeter of the object and in the field of view (3F, 3B, 3L, 3R) of that camera; and (b) calculating extrinsic parameters of that camera from the respective set of markers for that camera; and further: calculating a second set of extrinsic parameters for at least a second and a fourth camera of the plurality of cameras relative to the extrinsic parameters of the first camera obtained in step (b); wherein the second camera is a neighbouring camera of the first camera in a clockwise direction and the fourth camera is a neighbouring camera of the first camera in a counter-clockwise direction; calculating two second sets of extrinsic parameters for at least a third camera of the plurality of cameras relative to the extrinsic parameters of the first camera obtained in step (b) based on the result of step; (d) estimating a third set of extrinsic parameters for each of the plurality of cameras except the first camera relative to the origin based on the results of steps and; and (e) optimizing the sets of extrinsic parameters; calculating a second set of extrinsic parameters for at least a second and a fourth camera of the plurality of cameras relative to the extrinsic parameters of the first camera obtained in step (b); wherein the second camera is a neighbouring camera of the first camera in a clockwise direction and the fourth camera is a neighbouring camera of the first camera in a counter-clockwise direction; calculating two second sets of extrinsic parameters for at least a third camera of the plurality of cameras relative to the extrinsic parameters of the first camera obtained in step (b) based on the result of step; (d) estimating a third set of extrinsic parameters for each of the plurality of cameras except the first camera relative to the origin based on the results of steps and; and (e) optimizing the sets of extrinsic parameters;