Patent ID: 7720322

Claim:
A shape sensing method comprising: defining a lengthwise first segment in an optical fiber; defining a first three-dimensional reference frame at a start location of the first segment, wherein the first reference frame is a Cartesian frame, and wherein the first reference frame comprises a first axis that is normal to the fiber and a second axis that is tangent to the fiber; defining a Cartesian base frame at an origin location in the fiber, wherein the base frame comprises a first axis that is normal to the fiber and a second axis that is tangent to the fiber, and wherein the first axis of the first reference frame and the first axis of the base frame intersect a common core in the fiber; interrogating the optical fiber for data associated with strain in the fiber; outputting first bend information associated with the first segment, wherein the first bend information comprises a Cartesian position at an end location of the first segment with respect to the first reference frame; and determining a shape of the fiber with respect to the base frame by using the first bend information, wherein determining the shape of the fiber further comprises using kinematic chain characteristics for a portion of the fiber in which no shape sensing segment is defined.