As-Built Product Modeling and Reverse Engineering in Shipbuilding Through Combined Digital Photogrammetry and CAD/CAM Technology

Ship repair, as a technological "lesser brother" of shipbuilding, still contains major elements of manual labor. In the past years, ship repair and the conversion of ships and offshore structures came to rely increasingly on modern computer-aided design and manufacturing (CAD and CAM) information systems for speedy generation of the required engineering information. An often-encountered problem is the lack of product information in electronic form or in any other form. Such information is needed for engineering of new parts for damaged or converted ships and platforms. In such cases one needs to build the virtual product model from the existing as-built object up to an engineering-detail level; hence, the terms "as-built modeling" and "reverse engineering." The paper presents the results of a multiyear project with the code name AMORES, which focuses on improving lead time and economic efficiency in ship and offshore platform repair and conversion in the Netherlands. Existing and newly developed photogrammetric measuring techniques were used to generate as-built models of double curved three-dimensional surfaces of ships and platforms. These were fed into standard CAD/CAM systems to engineer and manufacture new ship hull or platform parts to replace damaged areas. The main advantages of the new method are savings in lead time (measurements, engineering) and the replacing of costly manual labor by modern digital photogrammetry. The paper will focus on the new developments, the experienced difficulties, and the advantages of this new technique in ship repair.