Proposta de um modelo geoidal geométrico local aproximado baseado em dados GNSS e nivelamento geométrico: análise comparativa com o MAPGEO 2015

The advent of Global Navigation Satellite System (GNSS) technology has made many advances in many areas of science and engineering possible. However, the altitudes obtained from positioning with this system are purely geometric in nature and unrelated to the gravity field of the Real Earth. For engineering works it is necessary to make transformations of geometric height obtained via GNSS to orthometric, especially in large works where the purpose depends on gravity gaps, for this, an alternative is the use of geoidal height models. The objective of this work is to propose an approximate geoidal local model for an area located in Sao Leopoldo-RS based on the integration of GNSS and Spirit Leveling data and comparatively analyze the model with MAPGEO2015 provided by IBGE. The results show that the proposed model has a minimum difference of -0.004m and a maximum difference of 0.200m compared to MAPGEO 2015, where the largest differences were found on the west side of the campus between landmarks 19, 31 and 33. Approximate Geoid Height model values range between 4,776m and 4,980m with an average difference of 0.128m.