Mosaicing for automated pipe scanning

The interior visual inspection of pipelines in the nuclear industry is a safety critical activity conducted during outages to ensure the continued safe and reliable operation of plant. Typically, the video output by a manually deployed probe is viewed by an operator looking to identify and localise surface defects such as cracks, corrosion and pitting. However, it is very challenging to estimate the nature and extent of defects by viewing a large structure through a relatively small field of view. This work describes a new visual inspection system (Figure 1) employing photogrammetry using a fisheye camera and a structured light system to map the internal geometry of pipelines by generating a photorealistic, geometrically accurate surface model (Figure 2). The error of the system output was evaluated through comparison to a ground truth laser scan of a nuclear grade split pipe sample containing artificial defects representative of the application – the error was found to be submillimetre across the sample.