Thanks for the reply Will.
In fact only part of this probem turned out to be the the target points not being close enough to the source cells - the real probelm is that the source cells in this case are polygons with more than four edges - and it appears that vtkProbeFilter just doesn’t support this cell topology.
I partially solved the problem using vtkDataSetTriangleFilter to convert these cells to triangles,
But I’m still not fully happy with the result. (This is a validPointMask plot
The source and target are different meshes on the same cylndrical shape - so the deviation betwen the two is really quite small - basically proportional to the chord/arc sagitta. The cylinder diameter here is 130mm and the target mesh cell size is around 10mm
It gets better if I assign a 5mm tolerance (although I would have expected this to map EVERY point)
