[vtkusers] SeedWidget with ImageViewer2 to get 3D locations

[kent williams]

I suspect that while it reports 3D points, they're really 2D, and you
have to fill in the Z coordinate.  You should know this anyway since
you use the sliderWidget to scroll through the volume.

I'm curious about your application. We're going to do the same thing
for picking points of interest in a volume.  Another developer in our
team is working on that, so I don't have hands on experience with the
vtkSeedWidget yet, but I suspect that it has the same idiosyncrasy
with respect to the coordinate system in which it reports points.  It
has methods that have 'WorldCoordinates' in the name, but in fact, the
X,Y,Z values are permuted such that X and Y are X and Y in the viewing
plane, and Z is the direction perpendicular to the viewing plane.

We use vtkinria3d's synchronized views instead of vtkImageViewer2, and
I don't know if the idea of coordinate systems in 2D views are exactly
the same, but we additionally have to negate the Y coordinate in Axial
views. So if your point values look upside down, that's one thing to
consider ;-)

On Thu, Feb 19, 2009 at 7:06 AM, Mark Gooding <mark.gooding at gmail.com> wrote:
> Hi there,
>
> I'm using an ImageViewer2 with a sliderWidget to scroll through a
> volume image (following an example I found in the archives when
> searching for a solution to this problem). I am also using a
> SeedWidget to select points from the current slice. The display XY
> co-ordinate seems to be picked correctly, however the slice selected
> by the seed widget is not the current slice, but appears to be fixed.
> Has anyone done something like this? Some pointers would be helpful.
>
> thanks,
>
> mark
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