Certain embodiments described herein provide methods, systems and computer-readable media for determining at least one location of at least one wellbore casing within a wellbore conductor. Sensor measurements generated by at least one sensor within the conductor are provided, the measurements indicative of at least one location of the at least one casing within the conductor as a function of position along the conductor. In certain embodiments, a data memory stores the measurements. The at least one location of the at least one casing is calculated using the measurements and at least one geometric constraint. The at least one constraint originates at least in part from at least one physical parameter of the conductor, or at least one physical parameter of the at least one casing, or both. In certain embodiments, a computer system or computer-executable component calculates the at least one location of the at least one casing.