In a first embodiment, a hollow gas turbine engine workpiece comprises first and second walls formed via additive manufacturing, and a cooling passage defined between the first and second walls by a surface of the first and second walls having arithmetic average surface roughness of at least 100 \u03bcin. The method comprises receiving, first and second pluralities of candidate anomalies, the candidate anomalies being identified in subsequent images produced with an imaging device. Moreover, the Location Based Service is assured of providing service to the computational device only at the authorized location.