[vtkusers] VtkVolumePicker choosing the edges of my volume

[David Gobbi]

The picker has a method called SetVolumeOpacityIsovalue()
that allows you to select an isovalue for picking.  As the
documentation states:

  "If you want to do the pick based on an actual data isovalue rather than
   the opacity, then pass the data value through the scalar opacity function
   before using this method."

So if you know the isovalue, then use the volume's opacity transfer function
to find the corresponding opacity.  Then call SetVolumeOpacityIsovalue().

 - David

On Thu, Mar 14, 2013 at 11:25 AM, Doug Hoppes <dhoppes at mbfbioscience.com> wrote:
> Hi all,
>
>
>
>                 Okay, not sure what is going on here.  I have an image stack
> that is pretty dark with a semi-white blob in the center.  I would like to
> be able to select any point on that blob.
>
>
>
>                 I find that I can do this, if I turn the pickable setting of
> the volume off, and create an isosurface for the semi-white blob.  However,
> ideally, I would prefer to just use the vtkVolumePicker to select the blob,
> rather than having to spend the time creating the isosurface.
>
>
>
>                 When I try to click on the white area of the blob, I always
> get the edges of the volume.  Is there a way to ignore the volume’s dark
> areas?  Since I don’t know what the exact pixel values are, is there a way
> to define a range of pixels to ignore (i.e. ignore all pixels < 10 and
> pixels > 100)?
>
>
>
> Doug