Self - calibration of an A ne Camera from Multiple

A key limitation of all existing algorithms for shape and motion from image sequences under orthographic, weak perspective and para-perspective projection is that they require the calibration parameters of the camera. We present in this paper a new approach that allows the shape and motion to be computed from image sequences without having to know the calibration parameters. This approach is derived with the aane camera model, introduced by Mundy and Zisserman (1992), which is a more general class of projections including orthographic, weak perspective and para-perspective projection models. The concept of self-calibration, introduced by Maybank and Faugeras (1992) for the perspective camera and by Hartley (1994) for the rotating camera, is then applied for the aane camera. This paper introduces the 3 intrinsic parameters that the aane camera can have at most. The intrinsic parameters of the aane camera are closely related to the usual intrinsic parameters of the pin-hole perspective camera, but are diierent in the general case. Based on the invariance of the intrinsic parameters, methods of self-calibration of the aane camera are proposed. It is shown that with at least four views, an aane camera may be self-calibrated up to a scaling factor, leading to Euclidean (similarity) shape reconstruction up to a global scaling factor. Another consequence of the introduction of intrinsic and extrinsic parameters of the aane camera is that all existing algorithms using calibrated aane cameras can be assembled into the same framework and some of them can be easily extented to a batch solution. Experimental results are presented and compared with other methods using calibrated aane cameras.