[ITK] VTK Deplacement Field Format

[Andras Lasso]

.vtk is the old generic VTK file format, replaced by the XML-based file formats (.vti, .vtp, ...). I would not recommend using .vtk file format for image storage, especially the ASCII version (because it's big and floating-point numbers are not represented accurately).

You can use MetaIO (.mha, .mhd) or NRRD (.nrrd, .nhdr) formats instead. They are both widely supported (ITK, VTK, 3D Slicer, ParaView, Matlab, etc.), well documented, and simple and efficient to parse.

Andras

-----Original Message-----
From: Community [mailto:community-bounces at itk.org] On Behalf Of Matt McCormick
Sent: Friday, September 12, 2014 2:45 PM
To: Armstrong, Hirotatsu
Cc: community at itk.org
Subject: Re: [ITK] VTK Deplacement Field Format

Hi James,

Yes, it looks like ITK's .vtk files writer is not following the standard very well, and it is printing six values per line [1].

The binary version will not have any newlines.

Hope this helps,
Matt


[1] http://itk.org/gitweb?p=ITK.git;a=blob;f=Modules/IO/ImageBase/src/itkImageIOBase.cxx;h=ae10e65dee1ecff0579d9ba43db9118c4466eec7;hb=HEAD#l656

On Fri, Sep 12, 2014 at 2:05 PM, Armstrong, Hirotatsu <HIROTATSU.ARMSTRONG at ucdenver.edu> wrote:
> Hello,
>
>
>
> I am having some trouble understanding the format of a .vtk file.  I 
> am deformably registering 2 CT images and saving the displacement 
> field in a .vtk file.  According to a pdf I found (for VTK v4.2), when 
> written in ASCII format, vector data should have 3 values on each line 
> corresponding to the x,y,z components for each vector.  When I write 
> my .vtk file, I get this,
>
>
>
>
>
> # vtk DataFile Version 3.0
>
> VTK File Generated by Insight Segmentation and Registration Toolkit 
> (ITK)
>
> ASCII
>
> DATASET STRUCTURED_POINTS
>
> DIMENSIONS 512 512 88
>
> SPACING 9.7656250000000000e-001 9.7656250000000000e-001
> 3.0000000000000000e+000
>
> ORIGIN -2.5000000000000000e+002 -1.0900000000000000e+002
> -1.5900000000000000e+002
>
> POINT_DATA 23068672
>
> VECTORS vectors float
>
> -0.0644559 -0.0859412 0 0.231144 -0.231144 0
>
> 0.242202 -0.201835 0 -0.211765 0 0
>
> 0.164835 -0.362637 0 0.159204 -0.437811 0
>
> 0.108108 -0.0405405 0 0.395062 -0.0493827 0
>
> -0.0987654 0.00493827 0 0.447702 -0.127915 0
>
> -0.167866 0.167866 0 -0.359551 -0.134831 0
>
> .
>
> .
>
> .
>
>
>
>
>
> Which is giving 6 values on each line.  I looked for some 
> documentation but couldn’t find anything other than the pdf.  Could 
> someone please point me to the latest documentation for the .vtk file 
> format?  Also, I originally wrote the files in binary format, but was 
> having some issue with that as well, which is why I switched to ASCII 
> so I can actually visualize the data.  The documentation is not clear 
> if there are newline characters included or not when binary data is 
> written.  I would assume not, but could this be clarified as well?
>
>
>
> Thanks
>
>
>
> James Armstrong, Ph.D.
>
> PostDoctoral Fellow, Physics
>
> Department of Radiation Oncology
>
> University of Colorado School of Medicine
>
> 1665 Aurora Ct, MS F706
>
> Aurora, CO 80045
>
> 720-848-0257
>
>
>
>
> _______________________________________________
> Community mailing list
> Community at itk.org
> http://public.kitware.com/mailman/listinfo/community
>
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