Short version: TopologyEdges (indices) changes when removing mesh faces (no surprise). But how do I map the new TopologyEdge indices to the earlier recorded indices?

So when removing some unwanted faces from a mesh, then:

- Before modifying the Mesh I
**record**(or “anchor”) all**NakedEdges**(indices). - Then I go about removing some unwanted
**MeshFaces**. - Then I check all NakedEdges (indices) again (some new NakedEdges must have emerged due to more faces being removed).
- Then I want to filter out all the “new” NakedEdges (by omitting the edges which was already there from start).
- Problem: The TopologyEdge indices are changed when the faces are removed (destroying my initially recorded naked edge indices).

**Q: Does anyone have a good strategy to share for a super-fast way of finding out which edge indices belong ONLY to the new naked edges due to the removed faces?** (If also the face indices are modified, then the road to salvation will be very narrow…)

This operation destroys my already recorded (topology edge) indices:

```
mesh.Faces.DeleteFaces(face_indices, false);
```

All ideas are welcome. Not expecting the code, only some interesting ideas.

// Rolf