Land surveying in Brazil: SIRGAS2000 and the shadow of the old datums
In a continent-sized country, eight UTM zones and three generations of datum history live side by side.
Field takeaways
- The official datum is SIRGAS2000; it practically coincides with GNSS.
- Production runs in UTM zones; the country spans 18S to 25S.
- Older maps sit in SAD69 or Córrego Alegre, tens of metres away.
- In the southern hemisphere, northings read against the 10-million false origin.
- The app opens in Brazil with the official system covering the location.
The official frame: SIRGAS2000
Brazil's official datum is SIRGAS2000, and it practically coincides with modern GNSS measurements. Production runs in UTM zones; the continent-sized country spans eight of them, 18S in the west to 25S in the east. A UTM coordinate given without its zone is uniquely meaningless in Brazil — the same numbers land in eight different places.
SAD69 and Córrego Alegre: two generations back
Before SIRGAS2000 came SAD69, and before that Córrego Alegre. A substantial share of archived maps and old projects still sits in those datums. Their gap to SIRGAS2000 is measured in tens of metres; comparing an old plan with today's measurement without a transformation ends with the gap mistaken for survey error.
The southern-hemisphere detail
In southern zones the northing reads back from the 10-million-metre false origin at the equator. Seven-digit northings starting with 9 are normal in Brazil; reading them with northern-hemisphere habits only confuses.
What the app does in Brazil
MapLab Survey opens in Brazil with the official system covering the location. Official networks, UTM zones and SIRGAS2000 sit together in the catalogue; you can bring in a plan in an old datum, compare it with the current measurement and export the delivery in the project's zone as DXF or CSV.
Two facts on every delivery
A Brazilian delivery should carry its zone and datum in the file: "UTM 23S, SIRGAS2000". Those two words are the only insurance against ten-metre surprises.
Try these steps on your own phone.
MapLab Survey handles RTK/GNSS point capture, drawing, area and volume calculations and coordinate conversion, then exports to DXF, KML/KMZ, GeoJSON, Shapefile, GeoPackage, NCZ or CSV. Capture, calculation and export work offline. Live NTRIP corrections and online basemaps need a connection.
Frequently asked questions
Which datum is official in Brazil?
SIRGAS2000; production runs in UTM zones and the country spans 18S to 25S.
Why is an old Brazilian map tens of metres off?
It is most likely in SAD69 or Córrego Alegre; the gap to SIRGAS2000 is of that order.
Why does the northing start with 9?
Southern-hemisphere northings read from the 10-million-metre false origin at the equator; that is normal.
Which system does the app open with in Brazil?
The official system covering the location; the catalogue lets you switch, old datums included.
Technical references
The field guidance in this article is aligned with the technical and official references below.
Related: Coordinate conversion app · Placing a scanned sheet · Bluetooth RTK GNSS · MapLab Survey