Released by the IBGE at the end of 2015, the new version of the Brazilian geoid undulation model (MAPGEO2015) was applied to the altitudes previously established by GPS receivers and updated the altitudes of the seven highest peaks in Brazil. Although not changing the ranking of the highest peaks in Brazil, this update established increases of 1.52m both in the Neblina Peak (the highest) and in the March 31 Peak (the second highest), which now measure 2,995.30m and 2,974.18m, respectively. The other five highest peaks had their altitudes reduced by less than one meter.

The establishment of altitudes in difficult-to-access locations always represented a major challenge to geosciences. Barometric leveling was used in the past. It used a barometer, an instrument created in the 17th century to measure the atmospheric pressure, altitudes and weather changes. Nevertheless, the measurements differ on an order of few meters. The introduction of positioning techniques associated with Global Navigation Satellite Systems – GNSS, particularly with Global Positioning Systems – GPS, started to provide high-precision coordinates (latitude, longitude and altitude).

In May 2004, the IBGE started the Pontos Culminantes (Highest Peaks) project using GPS technology. The project aimed at establishing more precise altitudes to the highest peaks in Brazil, using GPS tracking equipment and up-to-date techniques of precise satellite positioning. Implemented in partnership with the Military Institute of Engineering – IME, this project finished in 2005. Mount Roraima – in Pacaraíma Mountain, Roraima, Brazil-Venezuela-Guyana border – and the other six highest peaks were measured: Neblina Peak (Imeri Mountain, AM), March 31 Peak (Imeri Mountain), Bandeira Peak (Caparaó Mountain), Pedra da Mina Peak (Mantiqueira Mountain), Agulhas Negras Peak (Mantiqueira Mountain) and Cristal Peak (Caparaó Mountain).

However, the altitudes measured with a GPS receiver are not related to the average sea level – or, more precisely, to the geoid, which is the equipotential surface of the gravity field of Earth that matches the average sea level at rest –, but to an ellipsoid (see picture below), adopted as the geometric shape of Earth. As a result, the difference between the geoid and ellipsoid surfaces should be known – i.e., geoid height or undulation – in order to get the orthometric altitude (above the average sea level).

As more precise values of the geoid undulation in Brazil were unveiled with the release of MAPGEO2015 in November 2015, the altitudes of the highest peaks should be updated. This new geoid model was developed by the IBGE in partnership with the Polytechnic School of the São Paulo University – EPUSP.