# Local Cartesian System and Earths curvature

Hello,

Why then in any of the projects (JAG3D_Results_of_Compatibility_among_Network_Adjustment_Software):
Local cartesian system + Earth Curvature = local ellipsoidal system (with a=b)?

That is simply not true! If one adjust the 40 km network using the local Cartesian system and select the option Earth Curvature, the coordinates of the point M reads

M 3.8567191065322965E-5 23094.010829119456 0.007236303280461759

If one apply the ellipsoidal approach the result is

M -2.3686794627367602E-5 23094.01077588917 -0.001651724552338522`

Both results differ especially in the up component.

Kind regards
Micha

Yes you are right. I should have written "almost equal".
But in my example the difference is huge - 1250mm for a 4000m line.
(and this is taking into account the curvature of the Earth).
see 1.jpg; 2.jpg