COMPARATIVE ANALYSIS OF THE ACCURACIES OF DGPS AND TOTAL STATION INSTRUMENT IN PRECISE LOCATION OF GEOSPATIAL INFRASTRUCTURE

Abstract

Several techniques are employed in the determination of spatial position of infrastructures. Some of these techniques range from traditional method of Surveying such as trilateration, triangulation, traversing to the use of Differential Global Positioning System (DGPS). Most often, Surveyors are faced with the challenges of choosing the appropriate technique or instrument in acquiring spatial data. Questions are often asked about the best instrument among DGPS and Total Station in determining precise location of geospatial infrastructure. This study attempts to analyze and compare the accuracies of DGPS and Total Station in acquiring spatial data. Nine points were marked and beaconed. The area chosen was divided into two loops. DGPS and Total Station were used to obtain the Northing and Easting coordinates of the nine points. All the necessary checks were carried out. Efforts were made to ensure that the observations were done according to Surveyors Council of Nigeria (SURcON) Specifications. The results obtained were processed and comparatively analyzed. The result of the regression analysis shows that the coordinates obtained from Total Station compares favorably with those of the DGPS. Also, the total distance computed from DGPS and Total Station was compared. The total distance covered using DGPS and Total Station is 1998.916m and 1998.908m respectively. The variation between the distances gives 0.008m. The result of the analysis revealed that the linear accuracy of 1: 20,000 (loop 1) and 1: 24,000 (loop 2) were obtained using Total Station, while that of the DGPS is 1/150,000. The areas of the traverse network polygon as computed from DGPS and Total Station was also compared, the area covered by these networks is 84737.55sq.mtrs and 84713.024sq.mtrs respectively. The variation of average area from DGPS data with reference to Total Station data is 24.526sq.mtrs. It can be concluded that DGPS is more accurate than Total Station under normal environmental and atmospheric condition. 

Keywords: DGPS, Total Station, Accuracy, Geospatial Infrastructure, Analysis