Thanks for the update. It's not a bad idea to include this in the projections reader but ideally, it should calculate the permutation parameter automatically from the geometry. If it's optional, it's not a bad idea to have it in the projections reader pipeline, don't hesitate to submit if you have a clean PR.
On Thu, Apr 23, 2020 at 3:56 PM vincent <[email protected]> wrote: > 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]> 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 >> >> _______________________________________________ >> Rtk-users mailing list >> [email protected] >> https://public.kitware.com/mailman/listinfo/rtk-users >> >>
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