Clip from polygonal mesh?


I have a bit of a tricky problem to tackle with Paraview in terms of filtering / clipping.

I have a cell var (phi) which for phi=0 defines an an interface (surface). I would like to isolate each of these separately as if they were “bubbles” (see image below). Basically there is a large surface, and a bunch of smaller bubbles above (actually droplets) and below the large surface. If I use the connectivity filter, I am able to split these into separate surface meshes, which is what I want. Plus, if I order the regions by ascending cell count, the last region ID (largest) will give me the large surface (from which I can do other operations).
However, now I want to isolate exclusively the ones which lie below (lower Z value) the large surface. Any ideas on how I can do this ??

Some ideas I still have to try:

  1. If I can somehow extract the Z coordinate of the large surface, I could try to filter based on bubbles that have z < z surface ??
  2. If there is a way to “clip” the stuff just in 1 direction (negative Z) from the large surface , this would give me the bubbles that lie underneath.

Any other ideas?


Use the Clip filter ?

But what if it is not a plane / sphere/ etc ? If the Clip filter would allow me to select an arbitrary poly mesh to clip from, this might work.

That is not directly possible but this approach should work:

Thanks. I was trying, however not sure how to get the ‘Volume’ representation. I only have unstructured grid and polygonal meshes in my data. How can I create a suitable volume??


You can’t volume render surface mesh. Once you have applied the Contour filter, you have converted that the volumetric data into a surface mesh and hence can’t volume render anymore. You can turn on visibility of the “CellDataToPointData1” filter and the volume render that – not sure if that what you’re intending to do, however. What exactly do you want to volume render in your viz?

I was just trying to follow the steps from @mwestphal . It does complain about the fact that I am giving it a vtk Unstructured Grid and not vtkPolyData…