A RTK GNSS system was employed to improve accuracy of the data as discussed in Section ... . Here an EMLID Reach RS \cite{controller} was used as base station in conjunction with an EMLID Reach \cite{mapping} as rover module. The set-up of the base station follows the basic guidelines as discussed in Section ... and can be seen in Figure. The rover module set-up was not as sophisticated but still followed the most basic principles. The use of a monopod instead of tripod added a slight error to the measurements as the device was more or less handheld. The set-up can be seen in Figure ... If a tripod can be obtained and portability is not a critical factor it is definitely advised to use a tripod instead. 
Figures ... - ... display the settings that were used during data collection in the Field as set in the ReachView. For all possible options please refer to Section ... . 
Once the RTK data was downloaded from the devices post-processing began, as we, most of the time, didn't establish a direct connection between the rover and the base. To post-process the RTK data the corresponding EMLID developed software, RTKLIB, was used. It is a free software available for Windows, Mac and Linux and can be obtained from \cite{docs}. To process the data:
  1. Open the RTKCONV application.
  2. Add the rover raw log in the very first field and choose the output directory. 
  3. Choose the format in the drop-down menu: If obtained from each rover use u-blox, otherwise RTCM3 if both were obtained from the rover. 
  4. Open the 'Options'
  5. Ensure that the Version is set to 3.03 (Actual Version)