Abstract
Three-dimensional (3D) reconstruction using line structured light vision system commonly cooperates with motion restraint devices, such as parallel guide rail push-broom devices. In this study, we propose a visual positioning method to eliminate the motion constraint. An extended orthogonal iteration algorithm for visual positioning is proposed to obtain the precise position of the line structured light binocular camera system during movement. The algorithm uses the information acquired by the binocular camera, and produces a better positioning accuracy than the traditional vision localization algorithm. Furthermore, a global optimization method is proposed to calculate the poses of the camera relative to the world coordinate system at each shooting position. This algorithm effectively reduces the error accumulation and pose drift during visual positioning, and 3D information of the surface can be measured via the proposed free-moving line structured light vision system. The simulation and physical experiments performed herein validate the proposed method and demonstrate the significant improvement in the reconstruction accuracy: when the test distance is 1.5 m, the root mean square error of the point cloud is within 0.5 mm.
Highlights
Vision measurement is widely used in the field of industrial measurement [1,2,3,4,5]
To achieve a better practical effect and ensure reconstruction accuracy, an improved scheme was proposed for system positioning and posture optimization and an extended orthogonal iteration algorithm was designed for this system
To solve the problem of error accumulation in the push-broom process, a global optimization method was proposed and the simulation results showed that the extended binocular orthogonal iteration algorithm improves the accuracy of pose estimation between adjacent frames
Summary
Vision measurement is widely used in the field of industrial measurement [1,2,3,4,5]. Vision-based structured light measurement methods can effectively improve the precision of the measurement. There are various forms of structured light, such as dot structured light, line structured light and surface structured light. Dot structured light has low surface reconstruction efficiency and is only suitable for several special scenarios. Surface structured light is projected by a digital light processing (DLP) projector. Due to the power limitation of the projector, the surface structured light is normally more suitable for high precision reconstruction of small indoor workpieces than for large surfaces and outdoor scenes. Line structured light has strong light intensity and can be projected to long distance; its application is very extensive. Line structured light typically requires a push-sweep motion when reconstructing a measured surface. The traditional structured light push-broom device mostly relies on a parallel guide rail. In many cases, it is not suitable to use the guide rail that limits
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