====== Lambert93 ======

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 ([[glossaire:datum|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 [[english:glossary:ellipsoid|ellipsoid]] = IAG GRS 1980
  * Original [[english:glossary:meridian|meridian]] = international Meriden so the Greenwich’s Meridien 
  * Deformation compared to Mondial system: 
  - Horizontal between 1 and 2 cm
  - Vertical between 2 and 5 cm 
What’s more this geodesic system is compatible with the European one (ETRS89).
To decrease [[english:glossary:linearalteration|linear alteration]] the topographers prefer to work in Lambert 93 conic [[english:glossary:conformal|conformal]] in nine areas. 

\\ [[glossaire:Lambert 93|[French: Lambert 93]]]