An apparatus and method for merging a disjoint pair of maps comprising a digital building map that includes a floor plan and an access point (AP) map that includes identifiers for a plurality of access points is presented. In some embodiments, a first trajectory plot, of a mobile device, relative to the AP map, is received and a plurality of hypotheses is set, where each hypothesis defines a unique translation between the AP map and the building map. A plurality of costs may be computed for the first trajectory, where each cost of the first trajectory corresponds to a distinct hypothesis in the plurality of hypotheses. The hypothesis where the first trajectory has the lowest cost relative to the other hypotheses may be selected.