Portable and scalable measurement system for 3D measurement of large-scale complex surfaces based on fringe...

The 3D measurement of large-scale complex surfaces is widely used in large-scale manufacturing. The combined measurement method, based on close-range photogrammetry and fringe projection profilometry, can meet the needs for large-scale, high-precision, and high-density point clouds. However, it still faces limitations on measurement range and the accumulation of stitching errors in practical applications. Therefore, this paper proposes a portable and scalable measurement system comprising a digital single-lens reflex (DSLR) camera equipped with a zoom lens and a projector. The system's extrinsic parameters are calibrated on-site by laying appropriate circular-coded targets (CCTs) in the measurement area as local benchmarks. The measurement range of the fringe projection is matched by the telephoto end of the zoom camera, and the global benchmarks are established at the wide-angle end. The global optimization model determines the stitching pose. The splicing error is effectively reduced, and the measurement range is extended. Through 3D reconstruction and measurement of the vehicle body, the method's effectiveness is verified, and overall measurement accuracy can reach 0.8 mm/m.