[vtkusers] SeedWidget with ImageViewer2 to get 3D locations

[Mark Gooding]

Thanks, but I'd noticed :-). I have been using the 3D representation.
Will be replying to Kent's queries tomorrow when I'm at work.

Mark

2009/2/19 Karthik Krishnan <karthik.krishnan at kitware.com>:
> Mark:
>
> This depends on the representation for the handles that you
> are passing onto the seed widget. As you may be aware, we
> have both 2D and 3D representations. 2D representations are
> essentially vtkActor2D's and exist on the overlay plane and will
> be visible across all slices. My guess is that this is what you are using.
>
> Putting it in code....
>
> The following will create seeds that lie on the overlay plane with
> a behaviour you describe..
>
>   vtkSeedRepresentation *rep = vtkSeedRepresentation::New();
>   vtkPointHandleRepresentation2D *handle =
>       vtkPointHandleRepresentation2D::New();
>   rep->SetHandleRepresentation(handle);
>
> The following will create seeds that lies in world coordinates.
>
>   vtkSeedRepresentation *rep = vtkSeedRepresentation::New();
>   vtkPointHandleRepresentation3D *handle =
>       vtkPointHandleRepresentation3D::New();
>   rep->SetHandleRepresentation(handle);
>
>
>
>
>
> On Thu, Feb 19, 2009 at 10:07 AM, kent williams <nkwmailinglists at gmail.com>
> wrote:
>>
>> 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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>
>
> --
> Karthik Krishnan
> R&D Engineer,
> Kitware Inc.
> Ph: 518 371 3971 x119
> Fax: 518 371 3971
>