1. A system for registering a coordinate system for a shape sensing system to a coordinate system for pre-procedural or intra procedural imaging data, comprising: at least one instrument incorporating an optical fiber having shape sensing sensors; an optical console that interrogates the optical shape sensors; and determines the three-dimensional shape of the instrument; and a processor that registers the coordinate system of the shape sensing fiber to a coordinate system of imaging data; characterized in the processor registering the coordinate system of the shape sensing fiber to the coordinate system of imaging data by identifying a stable curvature in the optical fiber and matching the stable curvature in the optical fiber with a curvature from a different source and aligning the matched curvatures.