Instituto Brasileiro de Geografia e Estatística

It is a reference system composed of a geometric figure representing the Earth's surface, positioned in space, which allows for the unique location of any point on the surface based on its three-dimensional coordinates; it is materialized by a network of geodetic stations. Coordinates such as latitude, longitude, and altitude require a geodetic reference system for their determination.

Since February 25, 2015, SIRGAS2000 (Geocentric Reference System for the Americas) has been the only geodetic reference system officially adopted in Brazil. Between February 25, 2005, and February 25, 2015, the use of the SAD 69 (South American Datum 1969) and Córrego Alegre reference systems was permitted alongside SIRGAS2000. The use of systems lacking legal backing can lead to inconsistencies and inaccuracies when combining different georeferenced databases.

They are systems based on different concepts. While the definition and orientation of CA and SAD 69 are topocentric—meaning the origin point and orientation are located on the Earth's surface—the definition and orientation of SIRGAS2000 are geocentric. This means the system adopts a reference frame where the origin of its three Cartesian axes is located at the Earth's center of mass. Furthermore, the reference networks materializing these systems were established using different positioning techniques. While classical techniques (triangulation and traversing) were primarily used for CA and SAD 69, Global Navigation Satellite Systems (GNSS) were employed for SIRGAS2000.

For anyone who needs to receive or provide spatial information at relevant scales to and from the government and mapping agencies in Brazil. In short, for everyone who uses or produces geographic information.

They will not be able to, for example, request a property boundary revision, raise legal questions based on the old system, or exchange data with public utility companies for service provision or receipt.

To ensure the compatibility of geographic information, thereby facilitating information exchange among all parties—including between Brazil and other countries using systems compatible with SIRGAS2000.

By adopting a geocentric reference frame, it is possible to directly utilize GNSS (Global Navigation Satellite Systems) technology—a vital tool for map updates, national infrastructure projects and activities, transport fleet management, and real-time air, maritime, and land navigation. SIRGAS2000 enables greater precision in mapping Brazilian territory—and consequently in its spatial planning and border demarcation. Furthermore, the adoption of this system across Latin America has helped resolve various discrepancies between coordinates obtained via GNSS (specifically GPS and GLONASS today) and those derived from the maps previously used on the continent.

The coordinates representing the positions of objects undergo corresponding changes. For example, if the systems involved are SAD 69 and SIRGAS2000, these shifts are, on average, in the order of 65 meters.

Some did. The change is not noticeable on very small-scale maps, such as wall maps, where 1 cm corresponds to 5 km on the ground. However, on larger-scale maps—such as topographic sheets and cadastral maps—the difference in coordinates is significant, as illustrated in the answer to question 8.

Files, software, and services that assist with coordinate system conversion are available free of charge on the IBGE website, such as: SIRGAS2000 coordinates for stations in the Brazilian Geodetic System's horizontal network, the ProGriD coordinate transformation software, the Precise Point Positioning service (IBGE-PPP), etc.

Currently, there are no transformation parameters between SIRGAS2000 and WGS 84, because they are practically identical—that is, DX = 0, DY = 0, and DZ = 0.

Since the establishment of the GPS (Global Positioning System), its Geodetic Reference System (WGS 84) has undergone four refinements. The goal of these four updates has always been to bring it closer to the ITRF (International Terrestrial Reference Frame)—the most precise realization of the ITRS (International Terrestrial Reference System)—developed by the IERS (International Earth Rotation and Reference Systems Service). The most recent update is designated WGS 84 (G1674) and was adopted by the GPS system starting on February 8, 2012. The WGS 84/SAD 69 transformation parameters, published via IBGE Presidential Resolution No. 23 of February 21, 1989 (R.PR 23/89), remain valid for transforming coordinates determined by GPS positioning performed between January 1, 1987, and January 1, 1994—when the corresponding version of WGS 84 was known as WGS 84 (Doppler).

WGS 84 (Doppler) parameters for SAD 69:
DX = +66.87 m
DY = -4.37 m
DZ = +38.52 m

The SAD 69/SIRGAS2000 parameters used in ProGriD (option: SAD 69 Doppler Technique or GPS) and published via IBGE Presidential Resolution No. 1 of February 25, 2005 (R.PR 01/05), are valid for transforming coordinates between SAD 69/WGS 84 and SAD 69/SIRGAS2000 determined by GNSS positioning performed after January 1, 1994.

SAD 69 to SIRGAS2000 (≡ WGS 84 (G1150)):

DX = -67.35 m
DY = +3.88 m
DZ = -38.22 m

First of all, with the conclusion of the transition period to SIRGAS2000 on February 25, 2015, the results of any work must be referenced exclusively to this system. On the other hand, considering the information provided in the answer to question 11, WGS 84 can currently be considered—for practical purposes—coincident with SIRGAS2000. Therefore, the user simply needs to reference their results to SIRGAS2000 to automatically generate results in WGS 84 (and vice versa). As stated in the answer to question 11, the SAD 69/WGS 84 parameters published in R.PR 23/89 should only be used if the work was carried out prior to January 1, 1994.

The coordinates provided in the geodetic station reports were not obtained through transformation parameters, but rather through observation adjustments. The SIRGAS2000 coordinates originated from an adjustment performed in 2006. Although advanced techniques for modeling distortions in geodetic networks were employed during the development of ProGriD, transformations using this program always yield small residuals relative to the adjusted SIRGAS2000 coordinates. These small residuals correspond exactly to the minor differences detected when comparing the coordinates transformed by the software with those listed in the geodetic station report.

With the significant evolution of geodetic positioning techniques observed in recent decades—particularly following the advent of GNSS systems—coordinate determination precision has improved by up to three orders of magnitude. For instance, the coordinates of stations within the Brazilian Network for Continuous Monitoring of GNSS Systems (RBMC) are currently determined with millimeter-level precision. At this level of precision, various phenomena associated with Earth's crustal movements—previously imperceptible—become clearly detectable. In Brazil's case, the phenomenon contributing most to changes in planimetric coordinates (latitude and longitude) is the movement of the South American tectonic plate, which causes the entire territory to shift northwestward at a rate of slightly more than 1 cm per year. This annual variation highlighted the need to associate a reference epoch with geodetic station coordinates determined with millimeter (or centimeter) precision. For the country's official geodetic system, SIRGAS2000, the epoch 2000.4 was selected as the reference; this corresponds to the period of the SIRGAS campaign conducted in 2000 (specifically, in May of that year), during which 184 GPS stations across the Americas and the Caribbean were observed to realize the new system.