Precise levelling in crossing river over 5 km using total station and GNSS

Abstract

The trigonometric levelling using the simultaneous reciprocal method has been proved to meet the precision of second order levelling. But this method is invalid once the distance of river crossing is beyond 3.5 km due to the difficulty of target recognition at such a long distance. To expand the available range of this method, this paper focuses on solving the target aiming and distance observation over a long distance. A modular LED 5-prism (modified Leica GPR1 reflector) as an illuminated target instead of the common prism is introduced, and we adopt the sub-pixel image processing technique to recognize the center of the target image pictured by image assisted total station (Leica Nova TM50 I equipped with a coaxial camera). Based on the principle of precise trigonometric levelling, this paper utilizes two image assisted total stations using image processing technique to perform simultaneous reciprocal for zenith angle measurement and GNSS static measurement for slope distance measurement to determine the height difference of either river bank. And long-distance precise river-crossing levelling can be realized based on the mentioned above. Besides, it is successful to apply in the experiment of Fuzhou Bridge spanning 6.3 km in China. The result shows the standard deviation is ± 0.76 mm/km that is compatible with the precision of second order levelling has.

Development of a Dynamic Prediction Model for Underground Coal-Mining-Induced Ground Subsidence Based on the Hook Function

“…The leveling survey method conducted in the experimental campaign followed the specifications of China for thirdand fourth-order leveling, and the elevation error of closure was less than 8 mm for the leveling measurements. Based on the joint measurements of the GNSS and leveling survey, the polynomial surface fitting method was used to determine the height anomaly of the study area [23]. Then, the height anomaly was used to convert the GNSS geodetic height into the GNSS-based normal height.…”

“…(c) Construct the Jacobian matrix J and residual matrix f(x) using ( 24) and ( 26), respectively. (d) Calculate the cost function matrix ∆ using (23). (e) Update the optimal prediction model coefficients by:…”

A Method for the Precise Coordinate Determination of an Inaccessible Location

“…Moreover, similar approaches can successfully be utilised in the mining industry [6]. Examples of compelling applications and reports on developing spatial data integration methodologies are published in [7]-both cases concern deformation surveys and precise levelling based on the joint adjustment of multi-source data. In the case of open pit mines, one can observe a significant influence of atmospheric refraction and, at long distances, the Earth's curvature (plumb-line deviations).…”