DEVELOPMENT OF REALIZATION ALGORITHM OF COMBINED WAY OF VERTICAL REFRACTION CORRECTION FOR ELECTRONIC TACHEOMETRY
In electronic tacheometry, the standard refraction coefficient of 0.13 for the refraction effect accounting is used. In case of using this method the residual refraction effect is equal to several decimeters on a line of 1 km. The article presents a new technology of the refraction effect accounting. This technology is based on the usage of the geodetic model of atmosphere. The model allows predicting spatial variations of the refractive index and its gradients, taking into account the ground surface type and the sight line height above ground. The authors have formulated a principle that simplifies the mathematical apparatus of a geodetic model. There are three possible approaches to determination of parameters of the simplified geodetic model. These ways contain different sets of additional field measurements which are necessary for determination of atmospheric characteristics. The authors offer to use a combined method. This method is based on the complex of meteorological and geodetic measurements. An algorithm of the combined method implementation has been developed. The algorithm includes a new way for accounting of the height of the sight line. With this procedure a measurement of a zenith angle at an additional height is used to determine the «equivalent» height. labor intensive construction of a ground surface profile using the results of geometric levelling is then not necessary. The accuracy pre-calculation of the combined method has been executed. According to preliminary calculations the standard deviation of the combined method is about 13 mm for the line of 1 km.