A scanner assembly is provided that is configured to be mounted on a scanner manipulator arm, to be placed in proximity to an opening in a vessel or inserted into an opening in a vessel, and to measure distances from a scanner emitter/sensor within the scanner assembly to a plurality of points on the surface of a refractory lining of the vessel to characterize a concave interior of the vessel in a single scan. A scanner manipulator having the manipulator arm attached to the scanner assembly maintains the scanner assembly in measurement positions. A control system controls the position of the scanner assembly, the orientation of the emitter sensor, and the acquisition, storage, processing and presentation of measurements produced by the emitter/sensor. The field of view obtained from the scanner assembly in a single scan exceeds a hemisphere.