Sistemas geodésicos de referência adotados no Brasil e a conversão dos dados geográficos para o sistema oficial SIRGAS2000: transformações e avaliação de erros

Abstract

The evolution of science and technology permitted the improvement of Geodetic Reference Systems (SGR) over the time, in terms of definition and the system realization. In fact, this paper addresses issue related to the use of different SGR used in Brasil. The subject deserves a more consistent discussion regarding production and use of cartographic data in Brazil. This important topic is unknown or relegated to the background by many professionals who deal with spatial data and spatial analysis. The missing or underestimation of SGR can cause distortions in cartographic products and problems in resulting analyses if the data is processed improperly or misinterpreted. Thus the national cartographic products are referenced with support of different systems, namely: Córrego Alegre (realization 1961 and 1970/1972), Astro Datum Chuá, SAD69 (initial realization, 1996 realization Doppler or GPS realization), and lastly, SIRGAS2000 (materialization 2000.4) the current official system. In this context, this paper aims to describe the various existing Geodetic Reference Systems in Brazil and to make a comparative approach to coordinate discrepancies between them in Nova Lima - MG. The study concludes that the existence of metadata, the proper understanding of Geodetic Reference Systems and careful local analysis are essential for good results in spatial analyzes that require SGR conversion.