Assessing horizontal positional accuracy of Google Earth imagery in the city of Montreal, Canada

Abstract

The horizontal positional accuracy of Google Earth is assessed in the city of Montreal, Canada, using the precise coordinates of ten GPS points spatially distributed all over the city. The results show that the positional accuracy varies in the study area between ∼0.1 m in the south to ∼2.7 m in the north. Furthermore, two methods are developed for correcting the observed positional errors: (a) using a set of transformation parameters between true coordinates of the geodetic points and their coordinates in Google Earth, and by (b) interpolating the misfit vectors at the geodetic points. The former method reduces the overall accuracy to ∼67 cm RMSE, whereas the latter one practically removes all the distortion (RMSE = 1 cm). Both methods can be developed for other places in the world subject to availability of appropriate control points. In addition, a displacement problem caused by the topography of the area and the viewing angle of the imaging satellite is discussed, and it is shown that the true positions can be shifted even up to several meters, as a consequence.

Keywords:

• map calibration
• Google Earth
• GPS
• navigation

Additional information

Notes on contributors

Mohammad Ali Goudarzi

Mohammad Ali GOUDARZI. Dr holds a PhD degree in Geodesy from Laval University, Canada. He has been post-doctorate researcher at Laboratory of Space technologies, Embedded System, Navigation, and Avionics (LASSENA) at École de Technologie Supérieure (ÉTS), Montreal, for one year. During this period, he participated in the Vehicle Tracking and Accident Diagnostic System (VTADS) and worked on advanced sensor fusion techniques for autonomous navigation and optimal fleet management in harsh environments. He is currently works at Canadian Geodetic Survey as a geodetic engineer on real-time GNSS orbit improvement.

René Jr. Landry

René Jr. LANDRY. Dr received an electrical engineering degree at École Polytechnique of Montreal in 1992, a Master of Science in Satellite Communication engineering in 1993, a DEA in microwave in 1994 and a PhD in GNSS anti-jamming at SupAero in 1998. Since 1999, he is professor at the department of electrical engineering at École de Technologie Supérieure (ÉTS), and the director of LASSENA laboratory. His expertise in embedded systems, navigation, and avionic is applied notably in the field of transport, aeronautic, and space technologies.