Techniques for calculating a location of a position consumer device is disclosed. In one example, a network server may create a fingerprint map from reference data points. Each of the reference data points may include a recorded geo-location of a position source device and signal measurements taken at that recorded geo-location. By initially estimating an initial position of the position consumer device, the network server may apply one or more threshold values to filter reference data points—candidates for interpolation. The network server may then perform an interpolation on one or more pairs of reference data points to find a pair of reference data points that is collinear with the estimated position of the position consumer device. The location of the position consumer device may then be calculated based upon geo-locations of position source devices that are associated with collinear reference data points.