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

[Cornelis Bockemühl]

Thanks a lot Utkarsh!

It looks like your hints are giving me the theoretical background.
Additionally I realized that the vtkTimeSourceExample.h/cpp provides a
simple skeleton for implementing a filter that produces a time series
programmatically in C++.

Not finished yet, but I think I am on the right track now!

Regards, Cornelis


2017-09-19 15:58 GMT+02:00 Utkarsh Ayachit <utkarsh.ayachit at kitware.com>:

> 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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-- 
Cornelis Bockemühl
Basel, Schweiz
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