Image Stitching Based Rail 3D Profile Measurement

With economic development, China's railway transport undertakings have developed rapidly. The normal speed railway has speeded, and the rapid high-speed rail can be built quickly. Railway safety is asked higher requirements. Non-contact detection instrument is the trend of the development of railway safety. There are non-contact measurement equipment in in the market, but the FTP can reflect the three-dimensional profile rail. Long-distance measurement need image stitching and image fusion to store useful information.In image stitching, Harris corner detection, SUSAN corner detection and SIFT feature detection are compared. Although the corner detection has advantages in speed, Harris corner detection, SUSAN corner detection are not suitable. Because Harris corner detection requires a vertical line intersecting lines, but most of the actual fringe pattern is no vertical, and SUSAN corner detection method can't have a good performance of image detail. All in all, SIFT is suitable.In image fusion, Comprehensive weighted average and wavelet transform method can protruding overlapping parts' details, using wavelet transform, and go from a picture to another picture gently, using weighted average.In the case of computer simulation, FTP can get good results, which Relative error is 1.73%. In the test, Longitudinal relative error is 3.14%. The lateral relative error is 4.75%.