[Paraview-developers] Starter for generating time series of objects

[Utkarsh Ayachit]

Check out Section 13.2.2 in the ParaView Users Guide. It describes
steps needed for a Python Programmable Source that produces time.
That's pretty much the same thing you'd need to do in your temporal
filter.

A bit more background is available here:
https://blog.kitware.com/streaming-in-vtk-time/

Utkarsh

On Mon, Sep 18, 2017 at 10:33 AM, Cornelis Bockemühl
<cornelis.bockemuehl at gmail.com> wrote:
> Dear Paraview/VTK programmers,
>
> Right now I need to write a filter for Paraview that takes an "unstructured
> grid" as input and generates a time series as an output. I.e. a series of
> unstructured grids, derived from the first, with many points and data
> remaining the same and a few changing, including changing a few attribute
> values of cells and also changing the number of cells. No absolute time is
> required, so the steps can simply be numbered 0...1...2 etc.
>
> At this moment I am a bit lost about where to start for learning to do such
> a thing, so I would be happy with some starter: "look into ...
> documentation/tutorial" or "look into this .... source code"!
>
> The only possibility I see at this moment is to generate the unstructured
> grids timestep by timestep, write them as a series of VTK files with an
> index number in the file name, and then load it into Paraview.
>
> However, since Paraview can read such a sequence completely into memory -
> why should not my filter also do the same? But what is then what Paraview
> has in memory: a sequence of objects with timestamps somehow assigned?
>
> With this I would have the question of how I can assign a timestamp to an
> unstructured grid?
>
> Also the method of writing files first, then reading them seems a bit
> inefficient in terms of memory management: In my specific case a big number
> of data would remain the same, so they could be shared like they are also
> shared along a pipeline of filters - with unchanged arrays just being
> referenced and not copied.
>
> One more thing that I found out when trying to analyze the can example: If I
> read it from that can.ex2 file each one of the time steps has an explicit
> time value assigned - some very small number like 0.000<something>. If I
> write the object to a VTK file in full ASCII format in order to analyze it I
> do not find anywhere these time numbers. And if I read back the can example
> from the resulting can*.vtm series of files, the time stamps have
> disappeared and I see only 1...2...3 etc. Not a problem in my case (as
> already said above), but it leaves me again with the question of how to
> assign "time" to my data programmatically: In the VTK files the only
> indication seems to be the run index number of the file and subfolder names!
>
> So again: I would be happy with some helpful hints about where I can get
> more information about the subject, either explained or from sourcecode
> study!
>
> Thanks and regards,
> Cornelis
>
> --
> Cornelis Bockemühl
> Basel, Schweiz
>
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