Research On Adaptive Barcode Positioning Method Of Digital Level

The digital level is a new leveling measurement instrument capable with digitizing elevation measurement.It is widely used in terrain measurement,building measurement,crust deformation monitoring and other fields because of its advantages such as objective reading,high precision,high speed,easy operation,and easy integration of measurement inside and outside.Domestic high-precision digital leveling instrument mainly relies on importing.Each manufacturer's barcode has different coding rule and corresponding decoding methods.The barcode and measurement instrument are used together and cannot be exchanged,which makes the full use of resources received restrictions.Therefore,it is important to study the digital level measurement system,guarantee the accuracy,and increase the versatility of the digital level.Based on the above problems,according to barcode's common characteristics of black and white alternation with different widths,in the process of digital level sighting positioning,analyzing of digital level's coding principle and matching positioning methods,converting encoding rules to template images by setting equivalents.And then a fast adaptive correlation matching barcode positioning method is proposed,which be based on equal width for same stripes between the targeting measurement image and the template image.The positioning method is implemented in two steps-the coarse positioning and the accurate positioning.Firstly,the collected image was preprocessed by cutting and filtering to obtain the image to be matched.The scale factor of the matched image was obtained according to the same stripes with equal width between the matched image and the template image.The matched image is transformed to having the same width with template stripe image using bilinear interpolation method.Finally,the matching and precise positioning are achieved after shift-related operation between the matched image and the template image.In the coarse positioning,the shift step is a set of black and white bar width.Completing the accurate positioning is based on the coarse positioning,the shift step be reduced to a pixel.The barcode scale image processing and recognition and positioning are realized according to software designing.Building an experimental platform to verify the accuracy of matching positioning,height difference verification,and repeatability verification experiments for four barcodes.Leveling experiment results show that this method makes full use of the whole information of barcode image,has the characteristics of strong anti-interference ability,independence of coding rules,algorithm efficiency and high precision,which can be widely used for height measurement with different coding rules leveling.