If you select the entire head, many source points would be located in the skull and skin: FEM modelling is expected to fail for these points.
We need to capture this error and add clear error messages when trying to run FEM computation on source points outside of the inner skull surface.
@kenzo0619 Could you please copy-paste here the error you get when trying to use the full head volume?
@tmedani How do you detect and handle such points in the code?
Is switching from
cortex 15000Vtocortex(FEM)an acceptable way of making headmodel?
I don't see any problem with this solution. It is a different way to create a grid points, but all of them should be located within the brain.
If I selected with only the brain grid, does that mean the headmodel computation only uses the mesh of the inner layer without considering the conductivity of the rest four layers?
This grid of green points (as on the screen captures you posted) are the brain locations for which you want to estimate the electric activity. You should not have "brain sources" in the other layers.
If the difference between the "head model" (model explaining how the currents flow from the brain sources to the sensors on the skin) and the "source space" is not clear to you, get back to introduction tutorials on these topics:
https://neuroimage.usc.edu/brainstorm/Tutorials/HeadModel
https://neuroimage.usc.edu/brainstorm/Tutorials/SourceEstimation
As introduced in the tutorial, it is recommended to remesh from simNibs FEM output, since there is no error reported, is it still a compulsory step to do before making headmodel?