Remote crack-measuring system and device

The present study has developed a remote crack-measuring system based on the laser projection and image recognition techniques. With this system, users can measure the remote crack without touching the objects or placing reference scales, therefore, it is a safe and convenient crack-measuring method. For the laser projection, the formulas of laser spot coordinates have been derived, and the calibration procedure of laser projection angles has been established. On the other hand, for the image recognition, the grayscale tracking method and the threshold method are employed for the crack image recognition to give the crack parameters. Two test cases are conducted to validate the proposed remote crack-measuring system. The results show that this system can measure the crack length and width with sufficient accuracy.