Researches On The Key Technologies Of Digital Leveling

Digital leveling can realize automation on data acquisition, data processing and data recording in leveling survey. Only a few companies can produce digital leveling instrument. Of all the survey instruments, only the digital leveling has not been home-produced. It is blank for work of the detail principle and concrete realization of digital leveling instrument in civil researches.This paper focused on the key technologies of digital level. First, it briefly introduced the coding and reading principles of several existing digital leveling staff, and pointed out their common shortcomings. Then, an improved coding scheme on digital level staff was proposed. This coding rule used wide barcodes and narrow barcodes for different visual distance respectively, which also used digit scale to make optical leveling survey. Next, we get the two-dimension barcode image by area-array CCD, located the barcodes by mass-center detection, and decoded the barcodes using geometric construction. Based on above, a digital level staff barcode processing and recognizing software was designed in the Visual C++ 6.0. The software first of all pre-processed the barcode image in the visual field, including wave-filtering, binary-transformation, image smoothing etc., and then calculated the ratio of matter to picture and sight height of the target. Last, the performance of this scheme was evaluated by analyzing the data from experiments. The results indicate that this scheme is theoretically correct and practically feasible. The research lays a solid theoretical framework for the production of digital level.