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

[Cornelis Bockemühl]

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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