1. A method for creating a model of an object, comprising the steps of: (a) providing volumetric scan data produced by using a scanner to scan a region in which at least a portion of the object is disposed; (b) processing the volumetric scan data with a computing device to create a signed distance grid of points, each point in the signed distance grid corresponding to a vertex of a volumetric cell in the volumetric scan data and being associated with a signed distance value specifying a distance from the point to a surface of the object, a sign of the signed distance value for each point indicating whether the point is interior or exterior to the object; and (c) applying a unit magnitude gradient to the signed distance values, for determining an interval signed distance function representing the boundary of the object, to define a model of the object.