Motivation

The SIRGAS Project has included the necessary activities towards adopting a reference system in the continent, compatible with the modern position techniques, clearly associated with the Global Positioning System (GPS). Considering the wide use of GPS, referring the new surveys to an existing geodetic structure - established basically by classical methods (triangulation, traverse, trilateration, etc), with a precision at least 10 times worse than the one easily obtained with GPS- implies wasted resources at least . Besides, the various classical geodetic systems adopted by South American countries turn the solution of some technically simple problems, as international boundary definition, difficult to solve. On the other hand, the adoption of ITRS (International Terrestrial Reference System) as reference system, besides guaranteeing the homogeneity of the continental internal results, allows to a robust integration with others continent networks, contributing more and more to an actual global "geodesy".

History

The SIRGAS Project was created during the International Conference for the Definition of a Geocentric Reference System for South America, held at Asuncion, Paraguay, in October 1993, through an invitation by the following institutions:

. International Association of Geodesy (IAG)

. Pan-American Institute of Geography and History (IPGH) and

. National Imagery and Mapping Agency (NIMA).

This conference had a strong participation of South American countries' representatives, assuring, in that way, its success.

Objectives

In that occasion, the objectives of the project were defined, being the followings:

 

(1) To define a geocentric reference system for South America, being adapted ITRS, realized that time by the International Terrestrial Reference Frame (ITRF) of 1993, and the GRS-80 ellipsoid.

(2) To establish and to maintain a reference network; task delegated to Working Group I - Reference System (WG I)

(3) To establish and maintain a geocentric datum; task delegated to Working Group II - Geocentric Datum (WG II)