Extract z of continuous and derivable isosurfaces at mesh coordinates (x,y)

Hi,

I am trying to extract the values z at the mesh coordinates (x,y) of an isosurface generated by isosurface(X,Y,Z,v,threshold,v) where v is the function.

The generated isosurfaces are split into independent, continuous and derivable parts (with the function splitFV). This guarantees unique z values for each pair (x,y).

I would like to have access to the z values, instead of patches and vertices. How can I achieve this? Is there any function that allows me to find for instance an interpolated value?

Cheers!