[vtk-developers] changes in temporal support in VTK

[Yuanxin Liu]

Pat,
  That's correct. We will probably also have a super class or utility class
that the filter class can use to do the CONTINUE_EXECUTION and store the
multiple data sets.

Leo



On Fri, Apr 27, 2012 at 2:37 PM, Pat Marion <pat.marion at kitware.com> wrote:

> It sounds like a reasonable change to me (assuming the community is
> willing to accept the backward incompatibility.)  I've never used
> vtkTemporalDataSet, but I have used CONTINUE_EXECUTION.  Is it correct to
> say that this change doesn't remove any core functionality- by leveraging
> CONTINUE_EXECUTION a filter can accumulate multiple timesteps internally,
> with the same efficiency and memory usage as was possible before the
> change?  I like that removing vtkTemporalDataSet simplifies things since
> there is no longer two different ways to accomplish the same task.
>
> Pat
>
>
>
> On Fri, Apr 27, 2012 at 1:40 PM, Yuanxin Liu <leo.liu at kitware.com> wrote:
>
>> 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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