[Paraview] File Format for Particles

Fri Nov 28 11:20:06 EST 2008

Thank you Bryn and Ivo.

I agree binary format is more efficient. But I am reluctant to do that because of the issue of portability. I may run the code on both Linux clusters and IBM machines. My earlier experience shows me that the binary files on the two system are not compatible, i.e., I cannot load the data generated on a IBM machine  on a Linux system. Does the little/big endian parameter  solve this problem in paraview? 
Thanks.

Shi

----- Original Message ----
> From: Bryn Lloyd <blloyd at vision.ee.ethz.ch>
> To: Ivo Roghair <ivoroghair at gmail.com>
> Cc: Shi Jin <jinzishuai at yahoo.com>; paraview at paraview.org
> Sent: Friday, November 28, 2008 12:17:39 AM
> Subject: Re: [Paraview] File Format for Particles
> 
> Hi Shi,
> 
> Yes, for large amounts of data you should use the binary (not ascii) formats. It 
> is very simple to switch between ascii/binary. In the writer classes (e.g. 
> vtkPolyDataWriter) you can usually call the function SetFileTypeToBinary() or 
> SetFileTypeToASCII().
> 
> 
> An unstructured grid can of course be used to visualize your data in paraview. 
> Since you not have cells (tetrahedra, hexahedra, etc.) a vtkPolyData data 
> structure and associated file type might be better, since it uses slightly less 
> storage and if you add the points as "Verts" Paraview will automatically display 
> them using glyphs (sphere,arrow,..)
> 
> File formats are described here:
> http://www.vtk.org/pdf/file-formats.pdf
> 
> 
> --Bryn
> 
> 
> 
> 
> 
> Ivo Roghair wrote:
> > Hi Shi,
> > 
> > Saving such amounts of data in ascii format is not going to be efficient. We 
> just accepted this fact, otherwise we should go to binary formats.
> > 
> > In our group we have discrete particle simulations, and we export vtk files 
> (xml format -- an unstructured grid to be precise) that contains all the 
> particle data. I have included an example of such a file below. You write the 
> point positions of the particles first, followed by data concerning the movement 
> of the particle, the diameter and other stuff like rotation, temperature, etc... 
> I don't see what you mean by redundant data. When you load this file into 
> Paraview choose the glyph option, choose 'sphere', set 'radius' to 1 (it is 
> initially set to 0.5), scale mode to 'scalar' and scale factor to 1. You can 
> then draw the particles. You can color them by velocity, temperature, rotation 
> or whatever you included in the file, or you can choose to show arrows (another 
> glyph) to display the particle movement.
> > For the flow field, which is calculated on a structured grid, you can use 
> another file format, e.g. rectilinear grid. In all cases the kitware/vtk file 
> formats documentation is going to be useful.
> > 
> > Regards,
> > Ivo Roghair
> > 
> > PhD student at Fundamentals of Chemical Reaction Engineering
> > University of Twente, The Netherlands
> > 
> > ------------------ BEGIN EXAMPLE FILE ---------------------
> > 
> >  
> >    
> >      
> >        
> format="ascii">
> >        0 0 0 1 1 1 0 0 1
> >        
> >      
> >      
> >        
> format="ascii">
> >        4 4 4 4 0 0 2 2 -2
> >        
> >    
> >        0.1 0.5 1
> >        
> >    
> >        273 300 350
> >        
> >      
> >      
> >        
> >        
> >        
> >        
> >        
> >        
> >      
> >    
> >  
> > 
> > ---------- END EXAMPLE FILE --------------
> > 
> > Shi Jin wrote:
> >> Hi there,
> >> 
> >> I am doing a simulation of fluid-particle interactions, in which I generate a 
> lot of data for particles. I am looking for the efficient file format to store 
> my particle information for visualization with paraview. For example, is there a 
> file format that allows me to store all the particle information at a given time 
> in a single ascii file, which looks like
> >> #1-id 2-radius 3-rho_p 4-fixed 5-x 6-y 7-z 8-u 9-v 10-z 11-w1 12-w2 13-w3 
> 14-alpha 15-theta 17-phi
> >> 0 0.500000 1.200000 0 2.077176 2.678227 8.649375 0.000000 0.000000 0.000000 
> 0.000000 0.000000 0.000000 0.000000 0.000000
> >> 1 0.500000 0.800 0 2.728281 0.873571 6.806029 0.000000 0.000000 0.000000 
> 0.000000 0.000000 0.000000 0.000000 0.000000
> >> ...
> >> 
> >> I guess for the purpuse of visualization, we need radius, rho_p(for color), 
> x,y and z at least. The rotation information would be nice to have but is 
> considered optional at this stage.
> >> I am thinking to save different time results in different files to make the 
> loading efficient in terms of memory since I have a lot of particles here. Then 
> we can produce animation using time control. I guess we could use VTK formats 
> but that has lots of redundant information.
> >> 
> >> I saw some very early discussion on a similar topic in the forum but didn't 
> get the conclusive answer. I would appreciate some advice for the current 
> version of paraview.
> >> 
> >> Thank you very much.
> >> 
> >>  --
> >> Shi Jin, PhD
> >> 
> >> 
> >> 
> >>       _______________________________________________
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> >> ParaView at paraview.org
> >> http://www.paraview.org/mailman/listinfo/paraview
> >>  
> > 
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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
> -------------------------------------------------