A method for estimating the location of a mobile Wi-Fi signal receiver from a database of independently obtained survey data, each survey datum consisting of a surface of location derived from a composite GPS signal, together with a Wi-Fi signature measured concurrently with the GPS signal measurement, is disclosed. The method comprises receiving a Wi-Fi signature, measured and recorded by said mobile. Wi-Fi signal receiver, at the location to be estimated; extracting from the database, an algorithmically-determined subset of surfaces of location, utilizing the Wi-Fi signature recorded by said mobile Wi-Fi signal receiver, and estimating the location of said mobile Wi-Fi signal receiver from said algorithmically-determined subset of surfaces of location. In one embodiment, the algorithmically-determined subset consists of those surfaces of location with Wi-Fi signatures identical to the mobile Wi-Fi signature; and the estimate of the location of said mobile Wi-Fi signal receiver is determined as the point for which the sum of the squares of the distances to each of the surfaces of location included in said algorithmically-determined subset is minimized.