Satellite positioning based extension of geodetic reference network to support geospatial applications

Abstract

A national geodetic network provides the fundamental framework that enables attainment of high accuracy geodetic measurements. It plays a key role in the efficiency and reliability of operations in land surveying, mapping, remote sensing, Geographic Information System, engineering surveying and other related applications. The geodetic framework provides the basis for integrating all mapping and survey activities. About eighty per cent of the primary geodetic control points in Kenya, established in the early twentieth century, have been destroyed. This has resulted in expensive and time consuming operations and processes for geospatial professionals and scientists. This situation is particularly worse in central Kenya, hence the need to extend the geodetic control by establishing more control points on secure and accessible sites for use by geospatial professionals and scientists in a wide variety of applications. In this study, modern satellite positioning techniques were utilised to extend geodetic reference network in central Kenya. Existing geodetic control points were used to facilitate establishment of new geodetic control points distributed within the region. Field observations were carried out using Global Positioning System. The raw data were downloaded, edited, processed and adjusted using Leica Geo-Office software. The resulting final adjusted coordinates had a maximum standard deviation of 2cm and 5cm on horizontal and vertical coordinates respectively, and a general loop misclosure of less than one part per million. The results showed that the quality of established control point positions was high, and demonstrated the efficient extension of geodetic control network using modern satellite positioning systems and efficient computational techniques in situations such as the ones currently prevailing in central Kenya.