1. Ph.D. Candidate, Institute of Geodesy, Univ. of Warmia and Mazury, 1 Oczapowskiego St., Olsztyn 10-957, Poland.
2. Associate Professor, Institute of Geodesy, Univ. of Warmia and Mazury, 1 Oczapowskiego St., Olsztyn 10-957, Poland (corresponding author).
3. M.Sc., Institute of Geodesy, Univ. of Warmia and Mazury, 1 Oczapowskiego St., Olsztyn 10-957, Poland.