Variations in material thickness due to corrosion can be identified and graphically portrayed as an image.
The technique is widely used in the oil and gas industries for the in-service detection and characterization of corrosion in pipes and vessels.
The data is stored on a computer and may be color coded to show differences in thickness readings.
Corrosion may be mapped using Zero degree ultrasonic probes, an Eddy current array and/or Time of flight detection methods.
The book Nondestructive Examination of Underwater Welded Structures by Victor S. Davey describes a "fully automated dual axis robotic scanner used for corrosion mapping normally using a single zero degree compression probe scanned in a raster pattern over the area of interest."