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7741 |
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Wednesday, September 13, 2023, Brüssel 10:00 AM Research and Development |
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Digital visual testing of welds under water using optical 3D measurement technology with image-variant illumination |
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Oliver Kahmen* / Jade University of Applied Sciences - Institute for Applied Photogrammetry and Geoinformatics, Deutschland Robin Rofallski / Jade University of Applied Sciences - Institute for Applied Photogrammetry and Geoinformatics, Deutschland Thomas Luhmann/ Jade University of Applied Sciences - Institute for Applied Photogrammetry and Geoinformatics, Deutschland |
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Weld seams have complex surface geometries and finest structures. There are numerous standards for testing, which place different demands on the shape and the testing equipment. Geometries to be tested are often very small and the classification of different evaluation groups requires a high geometric resolution. The environmental conditions for visual testing are sometimes harsh and often present challenging inspection conditions. Poor visibility under water may, for example, limit an inspection task in terms of feasibility, quality and the time available at the measuring object. An underwater photogrammetric system with image-variant illumination is presented which can reconstruct weld seams three-dimensionally. Tests in the laboratory show that high measurement accuracies (<0.1mm) can be achieved even at very low visibility of approx. 20cm. Test-relevant geometries are digitally derived and the weld seam can be classified according to the applicable standard. The image data of differently illuminated scenes enable the creation of an image in which a “virtual torch” can be controlled interactively. Similar to the classic inspection process, the angle between the light source and the inspector´s eyes, respectively camera, can thus be varied to make irregularities more visible. At once, this method allows the temporal separation of data recording and data evaluation. This work contrasts the process of classical visual inspection under water in terms of data and documentation with the newly developed digital methods and shows the potential of optical methods in terms of the digitised visual testing. Wet-welded sample seams are 1. three-dimensionally reconstructed in the laboratory using a reference measuring system, 2. inspected with the aid of classical visual inspection and evaluated in accordance with ISO 5817 and 3. measured under water in situ with the developed optical system. The evaluation considers the test process, the data and the documentation. Potentials, such as the use of AI approaches for crack detection based on the newly acquired image data, are discussed and initial results are presented. |