[Gmsh] local mesh refinement of STL

[BRAUN Fabian]

Dear all,

For bio-impedance simulations I am creating a 3D volume mesh (of a human thorax) out of a 3D surface mesh from an STL file.

Now I would like my volume mesh to be finer in certain regions (e.g. aorta and heart regions have 10-fold finer mesh than the other elements).
What I've tried after having read the documentation (http://geuz.org/gmsh/doc/texinfo/gmsh.html#Specifying-mesh-element-sizes) is to seed the regions which I want to be meshed finer with a grid of points as follows:
Point(1)={x1,y1,z1,MaxSizeLocalRefined};
...
Point(N)={xN,yN,zN,MaxSizeLocalRefined};
However, I am unsure of how to embed these points into the volume of the STL mesh. (I guess they somehow need to be included into the Volume(1).)

Above there is the initial .geo file (without the point grid) which is automatically generated by the EIT EIDORS toolbox' function place_elec_on_surf.m (http://eidors3d.sourceforge.net/doc/eidors/models/place_elec_on_surf.html).
--------start geo file------
Merge "thorax.stl";
Surface Loop(1) = {1};
Volume(1) = {1};
Physical Volume('object') = {1};
Mesh.Algorithm3D=4;
Mesh.OptimizeNetgen=1;
-------end geo file-------

Any suggestions of how to modify the above geo file to force a finer mesh in certain regions?

Thank you very much for your hints in advance!
Best regards,
Fabian

PS: I'm running gmsh 2.8.5 on a Win64 machine

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