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

[Will Schroeder]

Great. Watch this space regarding parallel computing. There is a ton of
work going on (vtkSMPTools:threading; VTK-m:GPU & co-processors; and new
algorithms using both).

W

On Wed, Jun 3, 2015 at 3:46 AM, Dr. Miroslav Sejna <m.sejna at pc-progress.com>
wrote:

>  Thank you, Will. I'll definitely be interested in parallelization of my
> code, which will be done in a next step.
>
>
>
> Yesterday I fortunately found a simple solution for my problem. It is
> based on a custom additional array in PointData and overriding its virtual
> method "InterpolateTuple". This is the place where I can get all
> interpolation factors and save them for later re-use. The rest was just a
> routine programming. Now I'm able to display scalars and vectors (defined
> at nodes of the original FE-mesh) on modified VTK meshes
> (clipping/slicing/...) without recalculating these filters. It works
> exactly as I wanted. VTK is a great library - thanks again.
>
>
>
> Mirek
>
>
>
> *From:* Will Schroeder [mailto:will.schroeder at kitware.com]
> *Sent:* Tuesday, June 02, 2015 3:59 PM
> *To:* Dr. Miroslav Sejna
> *Cc:* vtk-developers
> *Subject:* Re: [vtk-developers] Optimization of vtkClipDataSet and
> vtkProbeFilter for large data?
>
>
>
> 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).
>
>
>
>
> --
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> 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
>



-- 
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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