Optimization of transformation of measurements of ship hull blocks

The paper presents an analysis of measurements taken on ship hull blocks to assess their feasibility for the final stage of assembly in a dry dock or on a slipway. The analysis requires first to check if blocks were manufactured within tolerances assumed in design and then to compare if two neighbouring blocks can be joined to each other. As each block is measured in a different coordinate system it is necessary to make transformations and bring results to a common CAD model without loss of accuracy. An algorithm for optimizing the transformation process to obtain better results, is proposed. The optimization is aimed at minimizing the sum of distances between transformed points and corresponding points in a CAD model. Description of the optimization method and example of its application is also presented. The problem of transformation of measurements or coordinate systems is more general as it can be found, apart from shipbuilding, e.g. in civil engineering, cartography, robot control, pattern recognition, medical imaging.