Determination of Support Systems to Improve the Accuracy of GNSS Surveys in Urban Areas of the City of Bogotá - Colombia

The satellite navigation systems (GNSS), had their beginnings in the seventies (70s), through the development of global positioning systems (GPS) by the United States and being functional at civilian level from 1993, when 24 satellites were achieved in orbit, which allowed to start the commercial race to implement services and technologies based on the position, among which may excel air navigation systems, vehicular routing systems, and geodetic and topographic surveys, In turn, other countries were developing similar systems, such as Russia of the former USSR with GLONASS, which developed systems parallel to U.S. technology, as well as Europe developed the GALILEO system and China Beidou, in order not to depend only on the authorizations and restrictions of U.S. systems, In this sense, this article presents a solution model to improve the accuracy of topographic surveys in the city of Bogota and surroundings with terrestrial support, which is based on the determination of the local geoidal model for Bogota version BGM2020v1. 0 and BGM2020v2.0, and the densification of the geodetic network of the city with the determination and retaking of more than 300 passive points, as well as the installation of 6 active reference stations, provided with the N-TRIP system and finally the generation of a high precision digital terrain model of 60000 ha of the urban area of the city from LIDAR.