Single-stripe-enhanced spacetime stereo reconstruction for concrete defect identification

Few studies explored the 3D reconstruction of concrete defects, and existing methods often suffer from noise interference or impracticality in real-world applications. This study proposes a novel single-stripe-enhanced spacetime stereo reconstruction method that combines a laser liner for structured light generation and a stereo vision camera. This method analyses the morphology and intensity variation of laser stripes from images captured from single scans, achieving accurate defect reconstructions. It is designed for handheld scenarios with image re-alignment eliminating the vibration caused by handheld operation. The morphology of laser stripes at crack sections is analysed for robust fine crack reconstruction. Active frame searching is introduced to improve the calculation efficiency, enabling spacetime stereo to operate over hundreds of frames. A comparative study of the proposed method and two commonly-used stereo matching methods demonstrates its ability to mitigate the impact of handheld operation and generate 3D reconstructions that highlight potential crack regions.