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IBGE makes simultaneous adjustment of the High Precision Altimetric Network

Section: Geosciences

June 20, 2011 10h00 AM | Last Updated: September 11, 2018 03h27 PM


IBGE publishes the updated data of the High Precision Altimetric Network (RAAP) of the Brazilian Geodetic System (SGB) in its web page on Monday, June 20. The publication is the result of the simultaneous adjustment of, approximately, 69 thousand stations, ended in June of 2011.

 There will be a presentation for users at 10 a.m. in the Center for Information Documentation and Dissemination (CDDI) at General

Canabarro Street, 706, Maracanã, Rio de Janeiro, RJ.

The updated information of the RAAP can be accessed at

In addition to portraying Brazil by means of statistical information, IBGE is responsible for the establishment of the Brazilian Geodetic System (SGB). The system encompasses a set of Geodetic stations, which provide official and highly precise information on latitude, longitude and height (the last two are called Level References – RRNN), of crucial importance in huge engineering constructions. The RRNN indicates the differences in level between two points of the surface of the earth. That difference is used to determine, for example, the way the water will pass by and, consequently, it is fundamental to support the construction or implementation of irrigation and water distribution systems, dams, roads, environmental, transportation and telecommunication projects, basic sanitation, agriculture. In sum, everything that concerns decision making regarding the infrastructure of the country.

The High Precision Altimetric Network (RAAP), a component of the Brazilian Geodetic System, is a network composed of 69,000 RRNN, established along roads and highways, which provide height in different points of the national territory, based on the mean sea level determined in Imbituba in Santa Catarina. In addition to the determination of the level differences, a series of analysis and estimates are necessary to obtain from data the best value for the height of a certain Level Reference. That process is called adjustment.

The High Precision Altimetric Network (RAAP) has been subject to several adjustments, according to its development and the tools available at each time. The last adjustment happened in the early 90s, but it was not simultaneous in all the network. In the beginning of 2005, a simultaneous adjustment was started and concluded in June this year.

That process resulted in the determination of new heights for all the RRNN, including stations that had preliminary values and around 12000 stations of which data had not been processed. The differences between the updated registrations and the previous heights were of up to 71 cm, values that might not interfere with daily life, but that are critical for activities that demand a high level of precision.