[vtkusers] vtkVolumeTextureMapper2D or ExtractVOI buggy?

[Lawrence M. Lifshitz]

[this is a repost of Incorrect Image Volume clipping when using ExtractVOI but with a simpler program which still shows the
problem and an attached image to try it on]

Hi.
I am trying to use ExtractVOI in conjunction with interactive slider widgets to adjust the volume seen by
a user.  But I find that once displayed, if I clip the image in low y to a small subset, and then try to translate the
volume in the window, the volume disappears before it reaches the upper window border.
I assume I am doing something wrong with clipping planes or pipeline updates, but am not sure what.
Attached is the code and a sample image.

Compile:
   g++  -Wno-deprecated -I/usr/include/vtk  -o DisplayVolume.o  -c DisplayVolume.cxx
   g++ -o DisplayVolume DisplayVolume.o /usr/lib64/libvtkCommon.so /usr/lib64/libvtkGraphics.so \
            /usr/lib64/libvtkImaging.so /usr/lib64/libvtkIO.so /usr/lib64/libvtkHybrid.so /usr/lib64/libvtkRendering.so \
            /usr/lib64/libvtkVolumeRendering.so /usr/lib64/libvtkWidgets.so /usr/lib64/libvtkFiltering.so  \
            /usr/lib64/libXt.so -lpthread

Run:
    DisplayVolume TestImage.mha

Then, don't rotate the image,
but  move the low y slider to clip out most of the image (e.g., to 85),
and then translate the image (Shift-left mouse to drag) up in y.
This causes the image to disappear at certain positions (high y) but before reaching the window boundaries. Why?
(note the same problem also appears on images which have an Offset of 0 0 0).


I am on fedora 16, 64 bit, with vtk 5.6.1-11 (rpms).
Can anyone tell me what I'm doing wrong?
Is there some debug/trace flag I can set in the future to help solve similar problems?
thanks.
              Larry

-- 
Lawrence M. Lifshitz, Ph. D., Associate Professor
Biomedical Imaging Group (http://big.umassmed.edu)
Program in Molecular Medicine
University of Massachusetts Medical School (http://www.umassmed.edu)
Phone: (508) 856-3392   email: Lawrence.Lifshitz at umassmed.edu
Fax:   (508) 856-1840     web: http://big.umassmed.edu/lml

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