[vtkusers] place arrows equally spaced along streamlines

[Dan Lipsa]

Cory,
That's a pity! It worked beautifully! :-)

I could not see any difference between streamlines generated from the
normalized vector field and the streamlines generated from the original
field.

I could not understand why and still don't as the interpolated vectors will
be different (and have different direction) if you normalize the original
vectors.
Maybe as Andy said, you'll still have the correct vectors in the points of
the dataset and the differences in the interpolated vectors are small.


On Mon, Mar 20, 2017 at 4:08 PM, Cory Quammen <cory.quammen at kitware.com>
wrote:

> Dan,
>
> Actually, I think I'm wrong. I think you would get different
> streamline results by changing the vector magnitudes. You'll
> definitely get evenly spaced glyphs by normalizing, though :-) Too bad
> the streamlines will be wrong.
>
> I can't think of any other tricks using existing tools in VTK to do
> this - you would need a scalar field along the streamline giving the
> distance from seed point.
>
> Cory
>
> On Wed, Mar 15, 2017 at 9:20 PM, Dan Lipsa <dan.lipsa at kitware.com> wrote:
> > Thanks Cory!
> > This works very nice!
> >
> > Dan
> >
> >
> > On Wed, Mar 15, 2017 at 12:08 PM, Cory Quammen <cory.quammen at kitware.com
> >
> > wrote:
> >>
> >> Dan,
> >>
> >> Another way would be to normalize your vector field, run the stream
> >> tracer on it, and then contour by integration time. That should give
> >> you evenly spaced samples along the streamline when you run the
> >> contour filter on it.
> >>
> >> A quick test of this in ParaView looks like it should work. See
> >> attached images. The one with the normalized velocity field has even
> >> spacing, the one with the non-normalized velocity field does not.
> >>
> >> Cory
> >>
> >> On Wed, Mar 15, 2017 at 11:44 AM, Dan Lipsa <dan.lipsa at kitware.com>
> wrote:
> >> > Hi all,
> >> > I would like to place arrow glyphs equally spaced along streamlines. I
> >> > am
> >> > using vtkStreamTracer.
> >> > The only way I see to do this is to add an option to vtkStreamTracer
> to
> >> > compute the distance from the seed and add this as a point data to the
> >> > the
> >> > streamline. Than, I can use contour to get the points where I need to
> >> > place
> >> > the arrows.
> >> >
> >> > Is there any other simpler way? Do you have any suggestions with this?
> >> >
> >> > Thanks,
> >> > Dan
> >> >
> >> >
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> >>
> >>
> >> --
> >> Cory Quammen
> >> Staff R&D Engineer
> >> Kitware, Inc.
> >
> >
>
>
>
> --
> Cory Quammen
> Staff R&D Engineer
> Kitware, Inc.
>
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