[Gmsh] extrusion of compound surfaces

[julien hoessler]

Dear Gmsh users/developpers,

I was wondering if there is a way to extrude a prism layer over a  
compound surface obtained by stl reparametrisation. I'm trying to  
import an stl file in order to generate a 3d prism/tetrahedrons mesh.  
I've checked your tutorial about stl remeshing (https://geuz.org/trac/gmsh/wiki/STLRemeshing 
) and tried to modify the artery example:

Mesh.RemeshParametrization=0; //(0) harmonic (1) conformal
Mesh.RemeshAlgorithm=1; //(0) nosplit (1) automatic (2) split metis

Mesh.CharacteristicLengthFactor=0.05;

//merge the stl triangulation
Merge "artery.stl";
CreateTopology;

Compound Surface(100)={1};
//One layer of prisms:
bl[]=Extrude{Surface{100};
	Layers{{1},{0.02}};
	Recombine;
};

But I end up with the following error:  Error : Impossible to extrude  
entity 100 (of type 307)
The way I used to generate my meshes was to generate a wireframe of  
isolines of my geometry and define a set of curved surfaces that I  
would later on extrude. I'm thus also really interested by  the trans- 
patch remeshing which would allow me to get a smoother mesh, but I  
also end up with a compound surface that I cannot extrude
Thanks again for your software
Best regards
Julien


Julien Hoessler
PhD Student
Department of Aeronautics
Imperial College London

Phone: +44 (0) 20759 45042
Email:   julien.hoessler06 at imperial.ac.uk