# Model Geometry

MARE2DEM uses a right-handed coordinate system with the z axis positive down. x is the model strike direction where conductivity is invariant, so $${\sigma} = {\sigma(y,z)}$$.

Note

There is no assumption about where $$z=0$$ resides in the model or data spaces, although generally it is recommended to set $$z=0$$ to be sea level. Similarly, transmitters and receivers can be located at any x position, but generally they should be close to $$x=0$$.