The increasing importance of GPS system and the necessity of geographic coordinates to be more and more precise has result in changing the geodesic system (datum) in France on January the 1st 2001. Thus, the French geodesic system 1993 or RGF93 or Lambert 93 has succeeded to the French new triangulation (in French NTF). Some features:

• Reference of the ellipsoid = IAG GRS 1980
• Original meridian = international Meriden so the Greenwich’s Meridien
• Deformation compared to Mondial system:

1. Horizontal between 1 and 2 cm
2. Vertical between 2 and 5 cm

What’s more this geodesic system is compatible with the European one (ETRS89). To decrease linear alteration the topographers prefer to work in Lambert 93 conic conformal in nine areas.

[French: Lambert 93]