[vtkusers] place arrows equally spaced along streamlines

[Andy Bauer]

For this you would have to normalize the vector after doing the
interpolation instead of on the full velocity field.

On Mon, Mar 20, 2017 at 4:13 PM, Andy Bauer <andy.bauer at kitware.com> wrote:

> If exact math was done with integrating the streamlines you should get the
> same result, regardless of the vector magnitude. Since we are numerically
> integrating though it may be off a bit.
>
> 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.
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
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