Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography (한국측량학회지)

Korean Society of Surveying, Geodesy, Photogrammetry and Cartography (한국측량학회)
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Development of GPS Multipath Error Reduction Method Based on Image Processing in Urban Area

디지털 영상을 활용한 도심지 내 GPS 다중경로오차 경감 방법 개발

  • Yoon, Sung Joo (Dept. of Geoinformatic Engineering, Inha University) ;
  • Kim, Tae Jung (Dept. of Geoinformatic Engineering, Inha University)
  • Received : 2018.02.07
  • Accepted : 2018.04.26
  • Published : 2018.04.30
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Abstract

To determine the position of receiver, the GPS (Global Positioning System) uses position information of satellites and pseudo ranges based on signals. These are reflected by surrounding structures and multipath errors occur. This paper proposes a method for multipath error reduction using digital images to enhance the accuracy. The goal of the study is to calculate the shielding environment of receiver using image processing and apply it to GPS positioning. The proposed method, firstly, performs a preprocessing to reduce the effect of noise on images. Next, it uses hough transform to detect the outline of building roofs and determines mask angles and permissible azimuth range. Then, it classifies the satellites according to the condition using the image processing results. Finally, base on point positioning, it computes the receiver position by applying a weight model that assigns different weights to the classified satellites. We confirmed that the RMSE (Root Mean Square Error) was reduced by 2.29m in the horizontal direction and by 15.62m in the vertical direction. This paper showed the potential for the hybrid of GPS positioning and image processing technology.

GPS측위는 수신한 신호를 바탕으로 계산된 위성의 위치와, 의사거리를 이용하여 수신기의 위치를 결정한다. 위성의 신호는 전달되는 과정에서 주변 물체에 의해 반사 및 굴절되는데, 이에 신호전달이 지연되어 다중경로 오차가 유발된다. 본 논문에서는 정확도 향상을 위해 영상을 활용한 다중경로 오차 경감 방식을 제안하고자한다. 연구의 목표는 영상처리를 이용하여 신호의 차폐환경을 계산하고 GPS측위에 적용하여 오차를 보정하는 것이다. 먼저, 영상의 잡음 제거를 위한 전처리 기법을 수행한다. 다음으로, 허프변환을 적용하여 건물옥상의 외곽선을 검출하고, 연산을 통해 차폐각과 허용가능한 방위각 범위를 계산한다. 이후, 영상처리 결과를 바탕으로 위성을 차폐에 따라 분류한다. 최종적으로, 분류된 위성에 서로 다른 무게를 적용하는 가중치 모델을 세우고 단독측위방식을 기반으로 수신기 위치를 결정한다. 실험에는 600개의 GPS데이터를 사용하였으며, 수평방향 RMSE의 경우 2.29m, 수직방향 RMSE의 경우 15.62m 오차가 절감된 것을 확인할 수 있었다. 본 연구를 통해서, GPS측위기술에 영상처리기술을 융합한 복합측위 방식의 가능성을 확인할 수 있었다.

Keywords

References

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