1. A method, comprising: defining, using a processing device, a nominal profile based on information from a known object; describing a surface of the nominal profile using a mathematical function; generating, using the processing device, an estimated profile from the mathematical function; defining a plurality of variable parameters of the mathematical function and their ranges to describe a profile space; selecting a variable parameter from the plurality of variable parameters within the profile space in the mathematical function; varying the variable parameter iteratively until a calculated diffraction pattern of the estimated profile matches the diffraction pattern of the known object; and storing, using the processing device, the estimated profile and the variable parameter.