AW: [Proj] differents results between cs2cs and proj

Gorling, Lothar L.Gorling at
Thu Jan 27 09:59:01 EST 2005


this is correct. In first script (proj-call) you make no datum-transformation and you take the same ellipsoid. You make only a tarsnformation from geographic coordinates to rectangle Lambert-coordinates.
In the second script (cs2cs) you make a datum-transformation from WGS and a transformation to another ellipsoid.

L. Gorling

-----Ursprüngliche Nachricht-----
Von: proj-bounces at [mailto:proj-bounces at] Im Auftrag von Lionel Barth
Gesendet: Mittwoch, 26. Januar 2005 15:15
An: proj at
Betreff: [Proj] differents results between cs2cs and proj


I am a new proj user.
I do not understand why I have differents results using the following 
proj and cs2cs scripts :

The script :
"proj    +proj=lcc +lat_1=45.8989 +lat_2=47.6960 +lat_0=46.8000 
+lon_0=2.33722917 \
      +a=6378249.2 +b=6356515 +x_0=600000 +y_0=2200000 \
      4.34878E 44.35930755N"
 answers "760474.90       1930742.15"

while the script :
"cs2cs    +proj=latlong +datum=WGS84 +ellps=GRS80 \
  +to    +proj=lcc +lat_1=45.8989 +lat_2=47.6960 +lat_0=46.8000 
+lon_0=2.33722917 \
      +a=6378249.2 +b=6356515 +x_0=600000 +y_0=2200000 \
      4.34878E 44.35930755N"
answers "760465.95       1931091.70 58.36"

The differences are 9 meters and about 350 meters. Does anybody know why ?

Thank you,
L. Barth

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