[vtkusers] Dynamic field probing?

David E DeMarle dave.demarle at kitware.com
Sat Aug 8 08:30:04 EDT 2015

You might use vtkValuePasses. This is a new class in vtk6.2 and note it has
not yet been ported to the OpenGL2 backend but I need to do that in the
next two months or so. See the tests for examples of its use. It was
developed for Cinema.

What it does is render specific arrays into the color buffer. Then with a
pixel color and the min and max values of the array you can recover the
value behind the pixel - within conversion to/from 24bit representation
tolerance that is. It is similar to the way selection works but with this
you will be able to skip the step of looking up the particular node/element
behind the pixel before recovering the value.

I have not yet used it for the exact purpose you describe, but I've meant
to since before I wrote it and should be able to assist.

David E DeMarle
Kitware, Inc.
R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909

On Fri, Aug 7, 2015 at 1:49 PM, Serge Lalonde <serge at infolytica.com> wrote:

> Hello VTK Users,
> I'm looking for for some pointers on adding dynamic field probing in my
> window as the mouse moves over (or hovers) over a field being displayed. I
> could implement it myself from scratch, but somehow I feel that there must
> be a "VTK-approved" method of doing it.
> Something like this:
> I found the vtkBalloonWidget and vtkProbeFilter, but I'm unsure how to use
> them separately or together to get what I want.
> Any suggestions are welcome. Thanks!
> --
> www.infolytica.com
> 300 Leo Pariseau, Suite 2222, Montreal, QC, Canada, H2X 4B3
> (514) 849-8752 x236, Fax: (514) 849-4239
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