Abstract:
The objective of this thesis is to evaluate the horizontal positioning accuracy and examine the effect of the triangular CORS networks (loops) geometric characteristics of RTK GNSS network with Virtual Reference Station (VRS) technique for the cadastral survey in Thailand. The data in this study consists of 2,122 test points, which were collected from 143 loops of triangular CORSs networks covering most parts of Thailand. There are two different methods conducted to process the data in this study - i.e. 1) The post processing of 90-minute static GNSS surveying used as the ground truth, and 2) The 15-minute RTK GNSS Network surveying with VRS technique as the testing points. This data is divided into four separated groups by the loop spacing of 30-50 km, 50-70 km, 70-90 km and 90-110 km, and also categorized by the characteristics of triangular CORS networks into three groups including 1) Equilateral triangle 2) Acute triangle and 3) Obtuse triangle. Moreover, the triangles are also classified as the Well-Conditioned Triangle and the Ill-Conditioned Triangle. The result shows that the efficiency of RTK GNSS network with VRS technique has direct correlation with the loop sizes. It could be said that RTK GNSS Network positioning with the smaller loop size of COR stations would be more accurate rather than the larger loop size, particularly the loops that smaller than 50 kilometers. In addition, all sample groups of this study including the largest loop size could provide averages of horizontal accuracy better than four centimeters. On the other hand, the geometric characteristics of triangular CORS networks seem to not have a significant effect on the horizontal position accuracy of the RTK GNSS Network with the VRS technique, unlike the loop sizes. All in all, it could be concluded that the RTK GNSS Network with the VRS technique is applicable for the cadastral survey in Thailand.