[vtkusers] which piece-filter streams when creating pieces to convert VTP to PVTP

[Grothausmann, Roman Dr.]

I noticed that when converting a VTP-file to a PVTP-file one must specify a 
filter in between the reader and the writer that actually creates pieces like 
vtkExtractPolyDataPiece (I guess that's why these examples are under broken: 
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Broken/IO/XMLPUnstructuredGridWriter 
http://www.vtk.org/Wiki/VTK/Examples/Cxx/Broken/IO/XMLPImageDataWriter). While 
my vtp2pvtp creates multiple files as expected 
(https://github.com/romangrothausmann/VTK-CLIs/blob/master/vtp2pvtp.cxx) I can't 
get it to stream the input. It seems that vtkExtractPolyDataPiece demands the 
whole dataset 
(http://www.vtk.org/gitweb?p=VTK.git;a=blob;f=Filters/Core/Testing/Python/StreamPolyData.py). 
So I wonder how to make this program single-threaded but streaming such that the 
total RAM usage scales with the number of pieces.

I also found vtkDicer vtkOBBDicer and vtkDistributedDataFilter which all seem to 
create pieces in different ways. When to use which and when 
vtkStreamingDemandDrivenPipeline?

Any help or hints are very much appreciated
Roman

On 26/11/15 12:19, Grothausmann, Roman Dr. wrote:
> Dear mailing list members,
>
>
> Due to apparent index limitations for arrays I'm in the need to process a
> vtkPolyData in chunks. However, my streaming approach reads and processes all
> data not just sub-extents. Therefore, I tried to write a minimal example of
> streamed reading using vtkXMLPolyDataReader which is supposed to support
> streaming according to the docs. However this simple example seems not to stream:
> https://github.com/romangrothausmann/VTK-CLIs/blob/master/read_SDP.cxx
> I've only found unanswered similar questions on the mailing list and all other
> use of vtkStreamingDemandDrivenPipeline seems to be within a filter not outside.
> Still, on page 14 of 4_VTK-ParallelCompositeAndTime.pdf the same exemplary use
> of vtkStreamingDemandDrivenPipeline is given for "manual" updates.
> Am I missing something in my example or can vtkXMLPolyDataReader not stream?
>
> Any help or hints are very much appreciated
> Roman
>

-- 
Dr. Roman Grothausmann

Tomographie und Digitale Bildverarbeitung
Tomography and Digital Image Analysis

Institut für Funktionelle und Angewandte Anatomie, OE 4120
Medizinische Hochschule Hannover
Carl-Neuberg-Str. 1
D-30625 Hannover

Tel. +49 511 532-2900