Extract the isosurface for 3D Scalar; and manipulate each fragments (integrations etc)

Dear all,

I have a 3D scalar in vtk format:
Collid_0051.vtk (1.1 MB)

I’d like to extract the isosurface of this 3D density field and performe integration over the
volume surrounding each isosurface (isosurfaces are disconnected).

Basically, I need to (1) extract the isosurface of a 3D scalar field, (2) analyse the connectivity
of the surfaces, and (3) calculate information for each subfragment.

Thanks a lot,