This study analyzed the influence of environmental conditions on the accuracy of total station measurements in forest environments, with a focus on the effects of local atmospheric refraction and observation conditions under dense canopy. Data was collected during two measurement campaigns (16/06/2023 and 20/06/2023), using the same instrumental setup and measurement geometry from a GNSS-determined station point. The results were validated indirectly through independent total station measurements from a separate GNSS-determined station located outside the forest perimeter, thereby ensuring stable reference conditions and eliminating GNSS signal degradation under the canopy. The analyzed point, physically established in the field, was identified as point 3000 and point 2000 in the two campaigns, representing the same physical location. The comparative analysis revealed significant planimetric deviations of 0.244 m and 0.670 m, corresponding to exceedances of 61–168 times the nominal instrument accuracy. The directional distribution of errors and their variability between campaigns indicated a systematic environmental influence, associated with local thermal gradients under the forest canopy. Through the systematic exclusion of instrumental, station, orientation and transformation errors, the results suggested that the primary source of deviations was local atmospheric refraction, amplified by the interaction of the EDM signal with the forest environment. This study highlights the limitations of standard atmospheric models used in total stations and emphasizes the need to adapt measurement strategies according to environmental conditions.

atmospheric refraction, total station, beech forest, 360° prism, Trimble S5, forest surveying, Stereo70, GNSS verification

geodesy engineering

Presentation: poster