[Insight-users] Confidence Connected Seed Coordinates

[Bill Lorensen]

Cameron,

The Seed coordinates are in pixels, not physical coordinates. IN
addition, VTK flips the image, so you  will need to flip your Y pixel
coordinate.

We should probably add a method to the filters with Seeds to accept
physical coordinates. Please add a feature request in the ITK bug
tracker.

This page explains how to submit a bug:
http://www.itk.org/Wiki/ITK_Procedure_for_Contributing_Bug_Fixes

Thanks,

Bill


On Mon, Apr 14, 2008 at 9:56 AM, Cameron Burnett
<w_e_b_m_a_s_t_e_r_6_9 at hotmail.com> wrote:
>
> Hi,
>
> I'm just wondering about the coordinate system of the confidence connected
> algorithm. I'm using a vtkPointWidget to select a seed point, and according
> to the point widget, my XY coordinates range from about -45,413 (top-left)
> to 413,-45 (bottom-right).... and also a z coordinate which I've got as 7.5
> (middle slice).
>
> Now, when I plug that into the confidence connected SetSeed() method, I
> don't think the two coordinate systems are matching up because my results
> are a bit strange.
>
>
> The following picture is an image of two legs, and you can see the
> vtkPointWidget being positioned in the center of the femur.
>
> http://img382.imageshack.us/img382/2118/dicomimgaw7.jpg
>
> This is the result of a multiplier of 0.1, followed by a multiplier of 2.
>
> http://img397.imageshack.us/img397/9743/outputvtk01multiplierwd7.jpg
> http://img383.imageshack.us/img383/6727/outputvtk2multiplierfs6.jpg
>
> (Note: I think these may be a bit pixely due to the compression on
> imageshack, but the actual ones are just 2 solid colours)
>
>
> What I conclude from that is that the blue area is in fact the area that has
> been seeded, not the red area. Therefore that is why I believe that I have
> some sort of problem with the coordinates not matching. What do I have to do
> to make sure the point widget and the SetSeed() method both match up??
>
> And I also don't know why there are 2 colours in the vtk file, when one
> should obviously be transparent. Is that one easy to answer?
>
>
> Thanks for any help,
> Cameron.
>
>
>
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