A method for verifying completion of a task. Location coordinates of at least one location sensor within a work cell are obtained. At least one sensor is affixed to a tool used to operate on a feature of a structure to be assembled, fabricated or inspected. A virtual object locus is generated based on the location coordinates of the at least one location sensor. The virtual object locus corresponds to a computerized schematic of the structure to be assembled and represents of all possible locations of an object end of the tool within the work cell. One of a plurality of candidate features is identified as the most likely to be the feature operated on by the tool. The identification is based on a probability calculation for each of the candidate features that each respective candidate feature is the feature operated on by the tool.