[IGSTK-Users] Transforming ImageSpatialObject then picking points

[Patrick Cheng]

Hi Sajendra,

Thank you for reporting this bug.

You are right, the current code does not take this user transform into 
consideration when transforming the points. It's calling the 
itkOrientImage: TransformPhysicalPointToIndex() and IsInside() directly.

There are two ways to fix this:

1. Add itkImageSpatialObject method which will deal with the user 
transform, and then calling those method in IGSTK code

2. Fix the IGSTK code directly

3. Pass on the user transform to the internal itkOrientImage, 
transform its origin and direction cosines

We need to think about which is the best way to deal with this 
situation. Will keep you updated.

Thank you,

Patrick



Nithiananthan, Sajendra wrote:
> Hello,
> 
> There seems to be a problem with ImageSpatialObject::RequestSetransform() .
> When it is called, the image will then be displayed properly at the new
> coordinates, but calls to ImageSpatialObject::IsInside() use untransformed
> coordinates.  It can then become impossible to pick points within the
> transformed image using the mouse.  
> I ran into this problem when reading a DICOM image which needed a
> non-identity transformation to map back to origin.  I tried fixing the
> problem by internally updating m_ImageSpatialObject inside
> igstkImageSpatialObject.txx but no luck, for now I have worked around it by
> modifying ImageSpatialObject so that it does not attempt to transform the
> image back to the origin.  I believe an example of this problem can be seen
> by loading the dataset "E000192Mod2" into the NeedleBiopsy example
> application and trying to pick some points near the edge of image.  
> If anyone wants I can provide a sample program that clearly demonstrates the
> problem.
> 
> Thank you,
> 
> Sajendra N.
> 
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