I. Introduction
As one of the most important issues in computer vision, structure from motion (SFM) has been studied extensively in computer vision [1], [2]. For SFM, the feature points may leave the field of view, or may be blocked by other objects in the tracking process [3]. When encountered such a condition, the feature points are invisible, and the corresponding measurements are missing. In the presence of missing data, some typical approaches of SFM, e.g. the factorization algorithm, cannot be used directly. Therefore, missing data estimation is generally a necessary preprocessing step of SFM.