"Temporal Particles To Path-lines" and "Temporal Interpolation" filters...do they require particles to be defined for every time step?

The output from my modelling software doesn’t define every particle at every time step and it seems to be causing havoc with two filters:

  • Temporal Particles to Path-lines filter: No path-lines drawn for particles if they aren’t defined for consecutive time steps, even if the particles new position is defined in a subsequent time step.
  • Temporal Interpolator: No interpolation, for the same cases as above.

e.g. for a very simple case with three particle and five time steps where particle 1 and 3 are defined at all time steps, but particle 2 is only defined at the first and last time step.

What I get for timestep 1, 2 and 3:

Particles 1 and 3 interpolate and have have path-lines, but particle 2 does not.

Is the simple answer to this that those filter really require every particle to be defined at every time step? Or is there a way to make those filters work under these circumstances?

I’m afraid this is the expected behavior of both these filters. That being said, if you have a way to identify which particle is which, it should be trivial to implement the filter you are looking for in a python programmable filter.

Thanks! I can code a script to populate interpolated particle locations for all the missing time steps, so that should do the job. That said, the python programmable filter sounds like it might be a better option? What would the general goal/output of the filter be such that it overcomes this problem? I currently only have in mind a bit of a brute force pre-processing method (i.e. generating interpolated particle locations for all time steps).

Both solution are ok.

The only complexity is that you need to keep a cache of previous timesteps in order to identify missing particles and compute the interpolation.

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That makes sense. I will attempt to pre-process my data for now, but will look at the programmable filters as soon as I can. Thanks!