[vtk-developers] Optimization of vtkClipDataSet and vtkProbeFilter for large data?

[Will Schroeder]

If I understand you correctly, it seems that your solution is to save in
memory the interpolation factors so that you can rapidly clip new attribute
data. Here's a probably crazy alternative suggestion that may have merit in
the long run.

You could take advantage of (emerging) parallel hardware and recalculate
the interpolation factors anyway; i.e., do extra work but with lots of
processors it may be simpler and faster. There are currently several folks
working on these sorts of algorithms (including clipping) but the results
will not be available until later this year. If you can afford to be
patient, or want to to try your hand at writing some parallel algorithms,
I'm sure we can point you in the right direction.

W

On Mon, Jun 1, 2015 at 4:34 PM, Mirek <m.sejna at pc-progress.com> wrote:

> Dear VTK developers,
>
> Filters like vtkClipDataSet and vtkProbeFilter, interpolating values of
> vtkDataSetAttributes, work perfectly for relatively small data, i.e. if the
> clipping is fast and you can have all vtkDataSetAttributes in memory.
> However, it looks like there is no option to optimize these filters for
> large data. In my case (see details (*) below), data of each quantity is
> loaded "on demand" from the disk. The problem is that vtkClipDataSet cannot
> interpolate new vtkDataSetAttributes into the existing (clipped)
> unstructured grid without recalculating everything, which is unnecessary
> and
> slow. In my old program, all "interpolated points" had information how to
> recalculate values of a new quantity (now vtkPointData scalars), which
> actually is a simple and fast operation. In case of a tetrahedral mesh, you
> just need to have IDs of 4 original mesh nodes and their weights for the
> linear interpolation.
>
> I have spent several days by debugging VTK and looking for a standard
> solution. Unfortunately, I have not found any way how to get and save the
> interpolation factors so that I could reuse them. The interpolation of
> vtkDataSetAttributes is implemented in vtkTetra::Clip and most of important
> functions (vtkTetra::Clip,  vtkDataSetAttributes::InterpolateEdge, ...) are
> not virtual => it will not be easy to modify the filter. Before investing
> time into the development of a new filter, I'd like to ask: Did I miss
> something?  Is there an existing solution for this problem?
>
> Thank you
> Mirek
>
> (*) In my case the data can be really large: unstructured FE-meshes with up
> to 50 mil. nodes and time-varying results (10-200 different quantities
> defined by values at mesh nodes, while there can be 100 - 10000 time
> layers).
>
>
>
>
> --
> View this message in context:
> http://vtk.1045678.n5.nabble.com/Optimization-of-vtkClipDataSet-and-vtkProbeFilter-for-large-data-tp5732100.html
> Sent from the VTK - Dev mailing list archive at Nabble.com.
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-- 
William J. Schroeder, PhD
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065
will.schroeder at kitware.com
http://www.kitware.com
(518) 881-4902
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