3D detecting technique for the inner surface of the pipe

A new 3D measurement technique based on ring structured light and LED illumination is proposed aiming to solve the detection of the inner surface of the pipes. It mainly consists of the following three steps: Ring structured light is firstly employed to draw the contour of the pipe section, and local depth information is retrieved from the contour image by image process and systematic calibration; LED illumination is then used to acquire the plane image of the inner surface, which is subsequently transformed to an expanded image with the knowledge of imaging principle, local 2D information for the inner surface can be obtained from the expanded image; 3D data for the inner surface of the pipe is ready by converting depth information and local 2D information to the global coordinates.