A method for determining corrected positions of a global navigation satellite system, GNSS, rover using a GNSS base station and a GNSS reference station, each of the GNSS rover, the GNSS base station, and the GNSS reference station being configured for real-time kinematic, RTK, processing techniques, the method comprising: arranging the GNSS reference station at a first location; determining a first average position of the GNSS reference station at the first location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a first instantaneous position of the GNSS reference station at the first location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a first position of the GNSS rover using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a first vertical correction based on the first average position and the first instantaneous position; determining a first corrected position of the GNSS rover based on the first position of the GNSS rover and the first vertical correction; thereafter arranging the GNSS reference station at a second location different from the first location; determining a second average position of the GNSS reference station at the second location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a second instantaneous position of the GNSS reference station at the second location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a second position of the GNSS rover using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a second vertical correction based on the second average position and the second instantaneous position; determining a second corrected position of the GNSS rover based on the second position of the GNSS rover and the second vertical correction. arranging the GNSS reference station at a first location; determining a first average position of the GNSS reference station at the first location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a first instantaneous position of the GNSS reference station at the first location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a first position of the GNSS rover using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a first vertical correction based on the first average position and the first instantaneous position; determining a first corrected position of the GNSS rover based on the first position of the GNSS rover and the first vertical correction; thereafter arranging the GNSS reference station at a second location different from the first location; determining a second average position of the GNSS reference station at the second location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a second instantaneous position of the GNSS reference station at the second location using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a second position of the GNSS rover using RTK corrections received from the GNSS base station and signals received from GNSS satellites; determining a second vertical correction based on the second average position and the second instantaneous position; determining a second corrected position of the GNSS rover based on the second position of the GNSS rover and the second vertical correction. <EOS>