How to delete internal intesected faces? The following mesh is created by converting a curve with bevel effect like below:



The mesh has some faces which extrude into the inside of the shape. This effect can be seen by cutting the mesh into halves (using boolean modifier):



If I want to get rid of the internal faces and only retain the outside faces which can be seen from this graph, what is the best way to achieve that without too much manual work? (I have a lot of characters to deal with, so I am seeking an automatic way)



I have tried clean the mesh up and use "Intersect (Knife)", but that does not do the job cleanly. It still misses some faces and leaving them extruded inside the shape. Basically I only want to keep the contour of the mesh. 

Attached a blender file for demo.
Shrinkwrap is actually the best way I can found and it works pretty well. Comparing to the heightmap approach talked about here BlenderExchange, the shrinkwrap approach is easier to operate and involves less processes.

Here is how I do it, first create a plane mesh over the beveled object, subdivide the surface with 30 slices:

 

Add subdivision surface and shrinkwrap modifiers.  The subdivisions need to set to 4 or 5. The mode of the shrinkwrap need to be "Project" (You might need to turn on "Negative" if "Positive" doesn't work.)

 

Apply the modifiers and edit the mesh. To do this easily, go to a side view and box select the vertices on the top layer, remove the vertexes:

 

Then you get a beautiful top contour without internal intervening faces:

 

The shape will have more details then necessary. Use limited dissolve to fix that 



End result: