[vtk-developers] changes in temporal support in VTK

[Yuanxin Liu]

Hi, Ken,
   Thanks for the suggestion.

   The order you suggested is exactly what I am following to make the
changes,

   I would also love to hear any interesting work flow /usage scenarios
related to temporal data.

Leo

On Fri, Apr 27, 2012 at 2:40 PM, Moreland, Kenneth <kmorel at sandia.gov>wrote:

>   The change sounds OK to me.  Although this class seemed like a natural
> thing to do when implementing temporal support, it has caused problems in
> unexpected ways.
>
>  I recommend flipping the order in which you implement this change.
>  First change all filters to not use vtkTemporalDataSet and replace that
> with CONTINUE_EXECUTION.  Make sure that the implementation is plausible,
> straightforward enough for users to implement, solve the problems we see
> with the current implementation, and don't introduce new weird problems.
>  After that remove vtkTemporalDataSet and the auto pipeline iteration,
> which at this point should be trivial.
>
>  -Ken
>
>    From: Yuanxin Liu <leo.liu at kitware.com>
> Date: Friday, April 27, 2012 11:40 AM
> To: VTK Developers <vtk-developers at vtk.org>
> Cc: Kitware-developers <kitware-developers at kitware.com>
> Subject: [EXTERNAL] [vtk-developers] changes in temporal support in VTK
>
>   Hi,
>   We are currently considering a few backward-incompatible changes to the
> temporal support in the VTK pipeline and would like to hear comments.  We
> are also interested in hearing other suggestions to improve handling of
> time-dependent data.
>
>   The main change is to remove the use of vtkTemporalDataSet and to limit
> the time request to be a single time step, i.e.
>
>    - Currently, a filter can request objects from multiple time steps by
>    setting the key UPDATE_TIME_STEPS to a vector of doubles; the resulting
>    objects get wrapped by the pipeline into a single vtkTemporalDataSet object.
>    - After the change, a filter can only request a single time step by
>    setting the key UPDATE_TIME_STEP to a single double.  The "wrapping" no
>    longer happens.
>
>   For existing filters that depend on multiple time steps,  we will modify
> them to use the CONTINUE_EXECUTION key to iteratively execute the pipeline
> and store the objects from the iterations.   There will be super
> classes/utility classes to make this easy.
>
>   The main motivation is that, by pushing the temporal functionality from
> the core pipeline to the filters, the execution pipeline becomes simpler
> and easier to maintain. Some bugs, e.g.( ParaView bug Id=6662<http://www.paraview.org/Bug/view.php?id=6662>)
> will go away as a result.
>
> Leo
>
>
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