Three-dimensional measurement

Three-dimensional measurement captures the as-built geometry of hull blocks and assemblies as a cloud of 3D coordinates, using photogrammetry, laser scanning, or a total station, then compares it against the design model to verify alignment and fit-up before blocks are joined. It checks block dimensions, butt and seam alignment, distortion, and the match between mating edges, so misfit is caught and corrected on the shop floor rather than at erection. The accept/reject limits come from the yard quality standard built on IACS Recommendation 47. Accurate 3D control cuts the rework and forced fit-up that lock residual stress into the structure and slow berth erection.