Hi,
just to bring some closure to that problem..
I didn't manage to adapt the ramp filter, so I instead modified
rtkProjectionsReader to include an Orientation parameter that sets the
right coefficients for an itkPermuteAxis filter.
I don't think it is worthy to be included in the official source, but I
am happy to share if someone requires it.
Best regards,
Vincent
On 15.04.20 20:13, Simon Rit wrote:
Hi Vincent,
Everything you did is correct but rtkfdk always applies the ramp
filter along the first dimension and does not check if this
corresponds to the direction orthogonal to the rotation axis. For your
case, it is probably not so difficult to adapt the code. When there is
a small rotation, it is debatable whether one should ignore the
rotation for the ramp filter, resample the image, or recalculate the
filter in 2D (see our recent publication here
<https://doi.org/10.1088/1361-6560/ab7875> which has not been
implemented in RTK). I have opened an issue on github
<https://github.com/SimonRit/RTK/issues/335>, hopefully we'll find
time to fix this in the future (at least raise an exception above a
parametrable rotation threshold).
Best regards,
Simon
On Wed, Apr 15, 2020 at 7:00 PM vincent <[email protected]
<mailto:[email protected]>> wrote:
Hi RTK community,
I hope everyone is doing well in those hard times.
I have a panel that is rotated by 90° on the CT system. I used to
rotate the images back in the right orientation before building the
sinogram with rtkprojections, but then I thought I might give a
try at
the "newdirection" option. Using the matrix [0 1 0 ; 1 0 0 ; 0 0 1]
gives the expected results. So far so good. But when I try to
reconstruct the latter with the same geometric parameters than for
the
pre-rotated projections, I obtain a very blurry result (vs a sharp
one
in the first case). I am obviously missing something, and I would
suspect I am not giving the right information to the rtkfdk
application. So far, here is what I have tried:
-keep the projections in the initial orientation, but give the
"newdirection" option to the rtkfdk application,
-specify the "newdirection" in both rtkprojections and rtkfdk,
-turn to you for advice !
I thank you very much in advance for any help you might be able to
give.
Best regards,
Vincent
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