Tracking-based 3D profile measurement technology using crossed multi-line lasers

Line laser-based 3D reconstruction is widely used in commercial products due to its high speed, strong adaptability, and broad applicability. Current methods often employ fiducial markers or motion devices for global point cloud stitching. Marker-based approaches are complex to operate and degrade point cloud quality near markers, while motion-based systems are costly and have limited measurement ranges. To address these issues, this paper proposes a point cloud stitching method based on stereo target tracking and develops a tracking-based cross-line laser 3D reconstruction system. The method uses a Canny algorithm-based gradient interpolation technique for high-precision target point extraction and tracking. Stereo 3D reconstruction is performed on the tracked target points. Leveraging the unique relative positions of stereo target points, the visible tracked points are matched with pre-calibrated points in a global 3D homologous set. This enables the calculation of the coordinate transformation between the handheld binocular system and the tracking system, allowing multi-frame point clouds to be converted into the tracking coordinate system without markers or motion devices. Experiments show that the reconstructed global point cloud has average absolute errors of 0.275 mm in the z-axis and 0.258 mm in the x- and y-axes. The system achieves a scanning speed of at least 84,000 points per second and a stitching range of no less than 800 mm × 800 mm, meeting the requirements for efficient, high-precision, and low-cost real-time scanning in large-scale scenarios.