1. A method of automatic spatial matching of models, the method comprising: providing, in machine-readable form, a first model comprising a definition of a three-dimensional solid; providing, in machine-readable form, a target model comprising a definition of the three-dimensional solid; identifying a first set of geometric entities in the first model that have a unique characteristic; identifying a second set of geometric entities in the second model that have the unique characteristic; and determining a best match between a member of the first set of geometric entities and a member of the second set of geometric entities.