1. A method for precise location of underground cables and pipes, comprising: measuring a set of complex electromagnetic field strengths at a plurality of positions along a path that crosses a target line; modeling an expected complex field strength at each of the plurality of positions with the target line and a hypothesized number of bleedover cables to form a set of hypothesized values corresponding to a set of individual models for the target line for each of the hypothesized number of bleedover cables; determining which of the set of individual models is a best model; and determining parameters related to the target line from the best model.