1. A method of determining a profile of a surface of an object comprising the steps of: obtaining and displaying an image of said surface of said object; determining the three-dimensional coordinates of a plurality of points on said surface; determining a reference surface; determining the three-dimensional coordinates of a reference surface line on said reference surface; determining the distance from said reference surface line to a plurality of points on said reference surface where surface-to-reference surface lines extending from said plurality of points on said surface are perpendicular to said reference surface and intersect said reference surface; determining the three-dimensional coordinates of a surface contour line on said surface based on the points on said surface whose perpendicular surface-to-reference surface lines intersect said reference surface on, or within a predetermined distance from, said reference surface line; and determining said profile of said surface by determining the distances from said reference surface to said surface contour line.