Apply Image Processing Techniques into the Process of Reading and Calibrating Levelling Staffs

Along with the development of the construction and geology industries, the field of geodetic measurement is increasingly focused on research. Therefore, the requirement to ensure the accuracy of the measurements was considered as well. Nowadays, the number of geodetic meters tends to be used more and more in the industry, hence, the demand for measuring and calibrating Levelling staff increases along with it. Levelling staff is a ruler widely used in the field of geodesy. Improving and enhancing the accuracy of the Levelling staff calibration method has always been a regular and urgent task for metrology agencies as well as organizations and companies operating in the field of geodesy. In fact, owing to the wide variety of sizes and types of Levelling staff, the mounting and measuring of different types of staff on the same measuring system face many limitations. The varied thickness and marking pattern of each type of Levelling staff is a challenge that makes it necessary to formulate a specified solution to carry out the measurements for each staff. This paper proposes a method to integrate camera and image processing techniques into measuring and calibrating Levelling staff using a laser interferometer. The automatic method of extracting the measured values saves considerable amount of time and improves the accuracy of the measurement. Experimental results of the system achieve resolution of less than 0.01 mm.