3D reconstruction methods and quality assessment for visual inspection of welds

Welding surface inspection and evaluation are the main tasks of the visual inspection process. The presence of flaws and/or geometrical imperfections can affect the safety of the structures. This paper presents an evaluation of geomatic techniques that complement the inspector expertise and knowledge during the visual inspection, by means of a dense and complete record of the weld. Particularly, an articulated coordinate measuring machine, widely used in industrial environments, versus a novel macro-photogrammetric technique are tested and compared thought an ad-hoc external reference frame, supported by 2D/3D registration artefacts and an automated identification methodology. The resulting 3D models are evaluated in terms of accuracy, precision and resolution. •Photogrammetry dense reconstruction allows exhaustive weld documentation.•Accuracy and precision for naval welding are assessed using robust estimators.•A submillimetre 3D model is obtained from an amateur camera.•Photogrammetric results are validated using a metrological laser scanner.