[vtkusers] Vectors in XML-format VTK files

[Bryn Lloyd]

Hi,


I am not 100% sure, but think this is just a visualization trick done in PV.

You should try the suggestion of Dominik and reverse engineer the XML 
format.


If you still need to visualize the vectors at the cell centers do the 
following:

In PV call Filters -> Cell Centers, and then display the glyphs.



Bryn











Deshpreet Singh Bedi wrote:
> Hi,
> 
> I have used legacy VTK file formats to view Vectors in other 
> visualization programs, such as VisIt.  The format I used was:
> 
> CELL_DATA 1
> VECTORS Spin double
> -0.449584 0.00705966 0.0459143
> 
> That should generate a vector at the center of the cell with vector 
> components vx, vy, vz given by the doubles above.  When I try to use the 
> same format in ParaView,  I run into a problem: instead of the desired 
> visualization, three vectors, each with the same direction and 
> magnitude, are shown.  I could not even get my vectors to be visualized 
> correctly in ParaView using the legacy format (even though it has worked 
> in other visualization programs), so I cannot yet use ParaView's 
> in-built file-format conversion functionality.  Any thoughts on what is 
> going on?
> 
> Thanks,
> Desh
> 
> On Wed, Oct 29, 2008 at 4:29 PM, Dominik Szczerba <dominik at itis.ethz.ch 
> <mailto:dominik at itis.ethz.ch>> wrote:
> 
>     -----BEGIN PGP SIGNED MESSAGE-----
>     Hash: SHA1
> 
>     Do you generate the file yourself (without VTK)? If so, I would start
>     with something simpler as a legacy file. Then load it into PV, save as
>     XML, and reverse-engineer the resulting file.
> 
>     Dominik
> 
> 
>     Deshpreet Singh Bedi wrote:
>      > Hi Dominik,
>      >
>      > Thanks for your reply.  One thing though -- what is the exact
>     syntax for
>      > including Vectors?  It is not precisely explained in the VTK File
>      > Formats packet.  I want the Cell Data that I include to be
>     visualized as
>      > vectors originating from the center of my cells in ParaView.  How
>     do I
>      > specify that?
>      >
>      > Thanks,
>      > Desh
>      >
>      > On Wed, Oct 29, 2008 at 3:52 PM, Dominik Szczerba
>     <dominik at itis.ethz.ch <mailto:dominik at itis.ethz.ch>
>      > <mailto:dominik at itis.ethz.ch <mailto:dominik at itis.ethz.ch>>> wrote:
>      >
>      > You can opt for immediate delivery and not a digest.
>      >
>      > If to use point or cell data is up to you and what you need.
>      > Cell-centered scheme means you have data defined at cell center,
>     in this
>      > case the length of the array has to be that of the number of cells;
>      > point-data means your data is defined at the points - in that
>     case the
>      > size of the array has to match the number of points.
>      >
>      > Dominik
>      >
>      > Deshpreet Singh Bedi wrote:
>      >> Hi,
>      >
>      >> What is the best way to include vectors in XML-format VTK files?
>      >  Should
>      >> they be included as Cell Data or Point Data?  What is the
>     difference,
>      >> and what is the format for each?
>      >
>      >> Thanks,
>      >
>      >> Deshpreet Bedi
>      >
>      >> P.S. If possible, I would greatly appreciate it if a reply could be
>      >> sent, in addition to the list-serve, directly to my email, as the
>      > daily
>      >> digest comes at far-too-widespread intervals.  Thank you.
>      >
>      >
>      >
>      >
>     ------------------------------------------------------------------------
>      >
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>      >
> 
>     - --
>     Dominik Szczerba, Ph.D.
>     Computational Physics Group
>     Foundation for Research on IT in Society
>     http://www.itis.ethz.ch
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> 
> 
> 
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-- 
-------------------------------------------------
Bryn Lloyd
Computer Vision Laboratory
ETH Zürich, Sternwartstrasse 7
CH - 8092 Zürich, Switzerland
Tel: +41 44 63 27690
Fax: +41 44 63 21199
-------------------------------------------------