[vtkusers] Merging two Unstructured Grids / Surfaces

[Karl Heinrichmeyer]

Hi together ..

I'm working at a project that uses Vtk to prepare intermediate results 
of different numeric simulations, all part of the engineering sciences, 
for the next simulation step. The data to work with are in general 
unstructured grids representing the geometry and properties of 
working-pieces while the simulations are something like welding and forging.

For one of this simulations i need to combine two input grids, that 
represent two working-peaces prepared for welding,  into one single 
surface. The two working peaces, in the actual case a gear-wheel and a 
ring, "lie on each other". That means the grids have contact and may 
intersect a little bit. The input consists of unstructured grids. The 
output has to be the combined surface of both grids without the contact 
surface. The mesh of this output surface isn't important while the shape 
has to match the input exact as possible.

I tried several things on my own and my current plan to proceed is the 
following:

  1. Extract the surfaces of both geometries using vtkDataSetSurfaceFilter
  2. Clipping the resulting polydata with each other using vtkClipPolyData
  3. Extracting the cutting edge with vtkFeaturedEdges
  4. "sewing" the edges by hand with an own algorithm
  5. put everything together.

My first question is: Has anybody a better idea to do this? And maybe: 
Is this possible at all?  I searched the vtk documentation quite a long 
time without results.

The second problem i found is to clip the surfaces with each other. I 
would need something like a vtkImplicitPolyData. I searched for 
something like this too but the only thing i found was a thread from 
2001. Is there something like an vtkImplicitPolyData in vtk that takes a 
polygonal surface and behave like an implicit function that can be used 
for clipping?

Thanks in advance.

Karl