[Paraview] Strange distributed volume rendering behaviour (CVS version)

[Paul Melis]

Hello,

I have a strange thing happening when volume rendering a somewhat large 
dataset (2000x2000x916) using a cluster running pvserver. Due to some 
practical considerations I have created a parallel file consisting of 25 
pieces (=number of cluster nodes), where each piece holds a subset of 
the 916 slices (I included the .pvti file below). Loading of the file 
from the paraview client running on my desktop works fine, but when I 
switch the representation to volume I get no visual output, just the 
axes. If, however, I edit the .pvti file to only include the first 14 
pieces and update the WholeExtent accordingly I can get the correct 
volume rendered output. When using the first 15 pieces there's no output 
anymore. I tried the last 14 and 15 pieces as well, to see if piece 15 
might be corrupt or something like that, but the behaviour is the same: 
14 pieces = fine, 15 pieces = not working.

Another strange thing is that when I tested with, for example, 15 pieces 
I need to use exactly 15 cluster nodes as using the full 25 causes a 
crash. Each node prints

  Process id: 9 >> ERROR: In 
/home/customers/melis/c/ParaView3/Servers/Filters/vtkKdTreeGenerator.cxx, 
line 164
  vtkKdTreeGenerator (0x8729858): RegionIDs cannot be 0.

and the connection to the client is lost. I seem to recall that on a 
smaller dataset that was split in 8 pieces there was no problem in using 
25 nodes.

Does my (perhaps unorthodox) split of the data cause these kinds of 
problems?

Regards,
Paul


<?xml version="1.0"?>
<VTKFile byte_order="LittleEndian" compressor="vtkZLibDataCompressor" 
type="PImageData" version="0.1">
  <PImageData Origin="0 0 0" Spacing="1.0 1.0 1.0" WholeExtent="0 1999 0 
1999 53 968">
    <PPointData Scalars="PNGImage">
      <PDataArray Name="PNGImage" type="UInt8"/>
    </PPointData>
    <Piece Extent="0 1999 0 1999 53 90" Source="piece_00.vti"/>
    <Piece Extent="0 1999 0 1999 90 127" Source="piece_01.vti"/>
    <Piece Extent="0 1999 0 1999 127 164" Source="piece_02.vti"/>
    <Piece Extent="0 1999 0 1999 164 201" Source="piece_03.vti"/>
    <Piece Extent="0 1999 0 1999 201 238" Source="piece_04.vti"/>
    <Piece Extent="0 1999 0 1999 238 275" Source="piece_05.vti"/>
    <Piece Extent="0 1999 0 1999 275 312" Source="piece_06.vti"/>
    <Piece Extent="0 1999 0 1999 312 349" Source="piece_07.vti"/>
    <Piece Extent="0 1999 0 1999 349 386" Source="piece_08.vti"/>
    <Piece Extent="0 1999 0 1999 386 423" Source="piece_09.vti"/>
    <Piece Extent="0 1999 0 1999 423 460" Source="piece_10.vti"/>
    <Piece Extent="0 1999 0 1999 460 497" Source="piece_11.vti"/>
    <Piece Extent="0 1999 0 1999 497 534" Source="piece_12.vti"/>
    <Piece Extent="0 1999 0 1999 534 571" Source="piece_13.vti"/>
    <Piece Extent="0 1999 0 1999 571 608" Source="piece_14.vti"/>
    <Piece Extent="0 1999 0 1999 608 645" Source="piece_15.vti"/>
    <Piece Extent="0 1999 0 1999 645 682" Source="piece_16.vti"/>
    <Piece Extent="0 1999 0 1999 682 719" Source="piece_17.vti"/>
    <Piece Extent="0 1999 0 1999 719 756" Source="piece_18.vti"/>
    <Piece Extent="0 1999 0 1999 756 793" Source="piece_19.vti"/>
    <Piece Extent="0 1999 0 1999 793 830" Source="piece_20.vti"/>
    <Piece Extent="0 1999 0 1999 830 867" Source="piece_21.vti"/>
    <Piece Extent="0 1999 0 1999 867 904" Source="piece_22.vti"/>
    <Piece Extent="0 1999 0 1999 904 941" Source="piece_23.vti"/>
    <Piece Extent="0 1999 0 1999 941 968" Source="piece_24.vti"/>
  </PImageData>
</VTKFile>