[IGSTK-Users] Viewer Problem due to TransformPhysicalPointToIndex

[Patrick Cheng]

Hi Fucang,

You are right, we are using the ITK image's
TransformPhysicalPointToIndex function, which does the truncation.

I will try to change it to TransformPhysicalPointToContinuousIndex, see
if it will do any better.

Thank you for the detailed email.

Patrick

Fucang Jia wrote:
> Hi, Patrick,
>  
> There is a problem due to TransformPhysicalPointToIndex function, which 
> belongs to Bug# 738,
> but it seems that this critial bug has not been fixed.
>  
> When I load IGSTK\Sandbox-Release-8\Testing\Data\E000192,
> press the left mouse button on the sagittal view in 
> FourViewsTrackingWithCT app continuously,
> then the index changes little bye one, when the index of sagittal viewer 
> was changed to 0, I press the
> mouse button onto the sagittal image, it says "Picked point outside 
> image". I tracked this bug,
> and found that it is due to index round up problem.
>  
> For example, the origin is  -153.6640625,
> the spacing is 0.671875
> the physical coordinate is 16.3203
> so the according index is
> (16.3203+153.6640625)/0.671875 = 252.9999813953,
> it was truncated to 252.
>  
> Then resliceImage function will change the orthogonal image slice.
>  
> I also found this behaviour will occur when certain DICOM dataset is 
> loaded. When I load other DICOM dataset,
> the axial and coronal slice will have problem, but sagittal view does 
> not change when mouse pressed. It is because
> that certain origin and spacing parameters trigger this problem.
>  
> Thanks!
>  
> Fucang
> 
> 
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