A system comprising: an elongate instrument having a proximal end, a distal end and at least one lumen defined therein; a housing coupled to a proximal portion of the elongate instrument, wherein the housing comprises an interface for receiving an actuating force and transferring the actuating force to the elongate instrument to articulate a distal portion of the elongate instrument; and a shape sensing fiber having a first portion and a second portion, wherein at least the first portion of the shape sensing fiber is positioned within the lumen of the elongate instrument. characterized in that: the system further comprises an anchor slide fixed to the second portion of the shape sensing fiber at a location external and proximal to the lumen of the elongate instrument, wherein the anchor slide fixes the location of the shape sensing fiber to the elongate instrument or a structure associated with the elongate instrument in one or more degrees of freedom, and wherein the anchor slide is configured to serve as a known location for matching a coordinate system of the shape sensing fiber to a coordinate system of the elongate instrument or other structure as the shape sensing fiber slides relative to the lumen of the elongate instrument, and a pocket within which the anchor slide is slidable only in the axial direction during installation. before being fixed in position; wherein the second portion of the shape sensing fiber is positioned within the housing, and includes a service loop, which allows for sliding of the shape sensing fiber within the lumen of the elongate instrument when the distal portion of the elongate instrument is articulated. an elongate instrument having a proximal end, a distal end and at least one lumen defined therein; a housing coupled to a proximal portion of the elongate instrument, wherein the housing comprises an interface for receiving an actuating force and transferring the actuating force to the elongate instrument to articulate a distal portion of the elongate instrument; and a shape sensing fiber having a first portion and a second portion, wherein at least the first portion of the shape sensing fiber is positioned within the lumen of the elongate instrument. characterized in that: the system further comprises an anchor slide fixed to the second portion of the shape sensing fiber at a location external and proximal to the lumen of the elongate instrument, wherein the anchor slide fixes the location of the shape sensing fiber to the elongate instrument or a structure associated with the elongate instrument in one or more degrees of freedom, and wherein the anchor slide is configured to serve as a known location for matching a coordinate system of the shape sensing fiber to a coordinate system of the elongate instrument or other structure as the shape sensing fiber slides relative to the lumen of the elongate instrument, and a pocket within which the anchor slide is slidable only in the axial direction during installation. before being fixed in position; wherein the second portion of the shape sensing fiber is positioned within the housing, and includes a service loop, which allows for sliding of the shape sensing fiber within the lumen of the elongate instrument when the distal portion of the elongate instrument is articulated. the system further comprises an anchor slide fixed to the second portion of the shape sensing fiber at a location external and proximal to the lumen of the elongate instrument, wherein the anchor slide fixes the location of the shape sensing fiber to the elongate instrument or a structure associated with the elongate instrument in one or more degrees of freedom, and wherein the anchor slide is configured to serve as a known location for matching a coordinate system of the shape sensing fiber to a coordinate system of the elongate instrument or other structure as the shape sensing fiber slides relative to the lumen of the elongate instrument, and a pocket within which the anchor slide is slidable only in the axial direction during installation. before being fixed in position; wherein the second portion of the shape sensing fiber is positioned within the housing, and includes a service loop, which allows for sliding of the shape sensing fiber within the lumen of the elongate instrument when the distal portion of the elongate instrument is articulated.