[vtkusers] Reslicing issues (Continued)

Scott Johnson Scott.Johnson at neuwave.com
Tue May 11 16:50:21 EDT 2010

Hello Xiaofeng,


You are my hero for the day!  Your change worked.


Based on your modifications I boiled it down to a single change to what
I had.  The vtkTransform attached to the vtkPolyDataMapper had to hold
the inverse of the vtkImageReslice reslice axes rather than the same
matrix.  I had the incorrect sense of this transformation in my mind, I
thought it was to transform from the original coordinate system to the
resliced coordinate system.  Actually it's the opposite.  I was looking
for the problem in the wrong part of the pipeline.


I appreciate your help.  Thanks.


                                -- Scott


From: Xiaofeng Z [mailto:xf10036 at hotmail.com] 
Sent: Tuesday, May 11, 2010 3:06 PM
To: Scott Johnson; VTK
Subject: RE: [vtkusers] Reslicing issues (Continued)


try the attached file and let me know if it works.
Notice that I use my own customized DICOM reader, which does not invert
the rows, hence the world x and y coordinate increases from lower left
corner to upper right corner on the screen.




Date: Tue, 11 May 2010 12:01:15 -0500
From: Scott.Johnson at neuwave.com
To: vtkusers at vtk.org
Subject: [vtkusers] Reslicing issues (Continued)

Hi Folks,


I officially throw myself on the mercy of the VTK Gods.


My platform is VTK 5.4.2 on Windows XP.


I've been working on this reslice issue off and on for awhile now and am
officially stumped.  I've worked up a piece of code which could
eventually be turned into an example for the examples list if desired.
I'll attach the code and a CMakeLists.txt file.  If the image data I've
been using is needed I'll need somewhere to put it.  (It's 22 MB zipped
and not suitable to attach to an email.)


The application is attempting to display resliced image data and an
intersection with a polygonal shape.  The Axial view works fine, but the
other views don't show the sliced sphere in the proper location.  They
do show up on the proper slice, but not in the proper XY location in the
viewport.  I seem to be running into a fundamental problem when
converting between the original image coordinate system and the resliced
coordinate system.


The attached code is annotated with 'PROBLEM' in the comments which is
outlining the problems I've been running into.  I'll chalk this up to a
learning experience which builds character.


Any help is appreciated.  Thanks


                                -- Scott




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