[vtkusers] Array order in VTK?

[Berk Geveci]

One thing that makes things a bit confusing is that, in the case of
vectors, the fastest growing is the vector component. So something like
this:

(0, 0, 0) u, (0, 0, 0) v, (0, 0, 0) w, (1, 0, 0) u, (1, 0, 0) v, (1, 0, 0) w

This makes it a hybrid Fortran and C. Which is pain when mapping these to
numpy arrays :-)

-berk

On Mon, Sep 19, 2016 at 9:51 AM, Elvis Stansvik <
elvis.stansvik at orexplore.com> wrote:

> 2016-09-19 15:24 GMT+02:00 Cory Quammen <cory.quammen at kitware.com>:
> > Elvis,
> >
> > VTK image data arrays are stored such that the X dimension increases
> > fastest, followed by Y, followed by Z.
> > Concrete example where dimensions of the image are XDIM, YDIM, ZDIM:
> >
> > Array index : i,j,k indices
> > 0 : (0, 0, 0)
> > 1 : (1, 0, 0)
> > 2 : (2, 0, 0)
> > ...
> > XDIM : (0, 1, 0)
> > XDIM+1 : (1, 1, 0)
> > XDIM+2 : (2, 1, 0)
> > ...
> > XDIM*YDIM : (0, 0, 1)
> > XDIM*YDIM + 1 : (1, 0, 1)
> >
> > So I guess that is Fortran order?
>
> Right, thanks for the clarification Cory.
>
> Elvis
>
> >
> > HTH,
> > Cory
> >
> > On Mon, Sep 19, 2016 at 1:40 AM, Elvis Stansvik
> > <elvis.stansvik at orexplore.com> wrote:
> >> Hi all,
> >>
> >> This is a simple question: I haven't been able to find any info on
> >> whether arrays (images, ...) are stored in row major (C) or column
> >> major (Fortran) order in VTK.
> >>
> >> I assumed they are in C order, but then I saw this blog post:
> >>
> >>     https://blog.kitware.com/developing-hdf5-readers-using-
> vtkpythonalgorithm/
> >>
> >> In a comment the author says
> >>
> >>     # Note that we flip the dimensions here because
> >>     # VTK's order is Fortran whereas h5py writes in
> >>     # C order. We don't want to do deep copies so we write
> >>     # with dimensions flipped and pretend the array is
> >>     # C order.
> >>
> >> which made me a little unsure. What is the array order of the data
> >> classes in VTK, and is it the same for all classes?
> >>
> >> Thanks,
> >> Elvis
> >> _______________________________________________
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> >
> >
> >
> > --
> > Cory Quammen
> > Staff R&D Engineer
> > Kitware, Inc.
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at http://www.kitware.com/
> opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
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