US Patent 10235577 Maneuverless passive range estimation using monocular image sequences

A method to estimate range to a moving rigid body from a moving platform using a monocular camera. The method does not require the camera platform to maneuver in order to estimate range. The method relies on identification and tracking of certain principal features of the object. The method extracts a silhouette of an object from an obtained image and identifies two principal linear components of the silhouette. A normalized distance between the point of intersection of the two linear components and a centroid of the silhouette is computed, compared to a data set and used to determine a direction of movement of the object.