1. A method, comprising: tracking a fringe line disturbance that has breached its field of reference; and, translating each pixel location of said tracked fringe line disturbance to an x,y,z s data point, where x and y represent a position on the plane of an interferometer's sample stage, and where z s represents the height of a sample above said x,y position, said sample placed upon the sample stage of an inteferometer so as to create said fringe line disturbance, said fringe line disturbance observed on said interferometer's detector.