[ITK-users] [ITK] help- find position of seed-levelset segmentation/connected treshold

[Sindhoor Bhat]

Hi Matt /ITK

Using TransformPhysicalPointToIndex I was able to get pixel index.
But in Z direction I've got negative value 44, 61, -157

I want to use this point as seed. But When I use this am getting black screen as output.

Is it ok to use -ve Z or should I do changes?

Also image index is not at the bottom left corner as mentioned in ITK manual. it is somewhere near mid bottom end

Can you pls give some light on this?
thanks







On Sunday, 8 June 2014 8:34 AM, Sindhoor Bhat <bhatsindhoor at ymail.com> wrote:
 


thanks Matt. Will try this.


On Sunday, 8 June 2014 1:09 AM, Matt McCormick <matt.mccormick at kitware.com> wrote:
 


Hi Sindoor,

itk::Image contains methods like TransformPhysicalPointToIndex [1]
that can be helpful.

Matt

[1] http://www.itk.org/Doxygen/html/classitk_1_1ImageBase.html#af4a7c9c3787e9fdafbaaade2e02efa25


On Sat, Jun 7, 2014 at 7:09 AM, Sindhoor Bhat <bhatsindhoor at ymail.com> wrote:
> Dear Matt/itk users,
> Now I'm able to pick world coordinates using vtk point picker widget.
> But for seed input to itk, we need index.  I'm really struck. can you pls
> help me how to move further? using itk-vtk interaction for seed selection?
>
> Also, to call vtk window for point selection which command should i use? (is
> it call-back function in
 vtk? But from itk how to call ?)
>
> thank you
>
>
> On Friday, 6 June 2014 6:04 PM, Matt McCormick <matt.mccormick at kitware.com>
> wrote:
>
>
> Hi Sindhoor,
>
> In your previous mail, you described taking sub-regions, which changes
> index positions.  To sample a value from a physical position, use an
> itk::InterpolateImageFunction.
>
> The apparent flip may be due to a difference in the direction and
> location of the Y-axis in your visualization programs.
>
> Hope this helps,
>
 Matt
>
> On Fri, Jun 6, 2014 at 1:03 AM, Sindhoor Bhat <bhatsindhoor at ymail.com>
> wrote:
>> Thanks Matt for your suggestion.
>> *But I've tried with that too. It is not considering the index/seed
>> position
>> that I write in program.
>> When I  added  below code to get selected seed position, it shows
>> completely different point than what I had written(using image J --->
>> physical coordinates )
>>                std::cout <<  filter->GetOutput()->GetPixel( Position1 ) <<
>> std::endl;
>> *seed point
 doesn't appear between selected thresholds ( say: (85,300) &
>> seep position will be like 45 etc)
>>
>> *Also, I should mention that my dicom images appear in reverse order(
>> flipped). Is this affecting my seed selection?
>>        (I tried subtracting Y coordinate from maxY etc.)
>>
>> Can you pls tell what is wrong? thank you.
>>
>
>
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