Assessment of Positioning Accuracy of UAV Photogrammetry based on RTK-GPS

RTK-GPS 무인항공사진측량의 위치결정 정확도 평가

  • 이재원 (동아대학교 토목공학과) ;
  • 성상민 (동아대학교 토목공학과)
  • Received : 2018.02.05
  • Accepted : 2018.04.06
  • Published : 2018.04.30


The establishment of Ground Control Points (GCPs) in UAV-Photogrammetry is a working process that requires the most time and expenditure. Recently, the rapid developments of navigation sensors and communication technologies have enabled Unmanned Aerial Vehicles (UAVs) to conduct photogrammetric mapping without using GCP because of the availability of new methods such as RTK (Real Time Kinematic) and PPK (Post Processed Kinematic) technology. In this study, an experiment was conducted to evaluate the potential of RTK-UAV mapping with no GCPs compared to that of non RTK-UAV mapping. The positioning accuracy results produced by images obtained simultaneously from the two different types of UAVs were compared and analyzed. One was a RTK-UAV without GCPs and the other was a non RTK-UAV with different numbers of GCPs. The images were taken with a Canon IXUS 127 camera (focal length 4.3mm, pixel size $1.3{\mu}m$) at a flying height of approximately 160m, corresponding to a nominal GSD of approximately 4.7cm. As a result, the RMSE (planimetric/vertical) of positional accuracy according to the number of GCPs by the non-RTK method was 4.8cm/8.2cm with 5 GCPs, 5.4cm/10.3cm with 4 GCPs, and 6.2cm/12.0cm with 3 GCPs. In the case of non RTK-UAV photogrammetry with no GCP, the positioning accuracy was decreased greatly to approximately 112.9 cm and 204.6 cm in the horizontal and vertical coordinates, respectively. On the other hand, in the case of the RTK method with no ground control point, the errors in the planimetric and vertical position coordinates were reduced remarkably to 13.1cm and 15.7cm, respectively, compared to the non-RTK method. Overall, UAV photogrammetry supported by RTK-GPS technology, enabling precise positioning without a control point, is expected to be useful in the field of spatial information in the future.


Digital Surface Model;Orthoimages;Positioning Accuracy;Real Time Kinematic;UAV-Photogrammetry


  1. S. M. Sung and J. O. Lee, "Accuracy of Parcel Boundary Demarcation in Agricultural Area using UAV-photogrammetry", Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography, vol. 34, no. 1 pp. 53-62, 2016. DOI:
  2. S. B. Lim, O. C. Seo and H. C. Yun, "Digital Map Updates with UAV Photogrammetric Methods", Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography, vol. 33, no. 5 pp. 397-405, 2015. DOI:
  3. H. Burman, "Calibration and Orientation of Airborne Image and Laser Scanner Data Using GPS and INS", Dissertation, Royal Institute of Technology, Stockholm, Sweden, 2000.
  4. Pix4D[cited 2017 Aug 29], Available From: Feb., 25, 2018)
  5. M. Rieke, T. Foerster, J. Geipel and T. Prinz, "High-Precision Positioning and Real-Time Data Processing of UAV-Systems", IASPRS, Volume XXXVIII-1/C22, pp. 119-124, 2011.
  6. C. Elling, L. Klingbeil, M. Wieland and H. Kuhlman, "A Precise Position and Attitude Determination system for Lightweight Unmanned Aerial Vehicles", IAPRS, vol. XL-1/W2, pp. 113-118, 2013. DOI:
  7. M. Gerk and, H. J. Przybilla, "Accuracy Analysis of Photogrammetric UAV Image Blocks: Influence of Onboard RTK-GNSS and Cross Flight Patterns", Photogrammetrie, Fernerkundung, Geoinformation (PFG), no. 1 pp. 17-30, 2016.
  8. H. Fazeli, F. Samadzadegan and F. Dadrasjavan, "Evaluating the Potential of RTK-UAV for Automatic Point Cloud Generation in 3D Rapid Mapping" IAPRS, Volume XLI-B6, pp. 119-124, 2016. DOI:
  9. J. K. Park and M. G. Kim, "PPK GNSS System based UAV Photogrammetry for Construction of Urban Disaster Prevention Information", Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology, vol. 7, no. 4 pp. 355-362, 2017. DOI: