[Paraview] Point swarm with one cell

[ben]

I have a point swarm (output from Underworld thermal model), with one 
cell, and 32768 points. I cannot seem to get any sort of visualisation 
from it after filtering. If I apply a Threshold filter to 'remove' some 
of the data, nothing shows at all.

If I first apply a Clip filter, but set it outside the range of the 
data, then the result is a dataset with 32768 cells, and 32768 points. 
The Threshold filter works after that.

Why is this?


Ben