Hi Simon,

thank you for your reply !

I'll have a look at the code to try and adapt and let you know if I succeed.

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 <v...@xris.eu <mailto:v...@xris.eu>> 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
    Rtk-users@public.kitware.com <mailto:Rtk-users@public.kitware.com>
    https://public.kitware.com/mailman/listinfo/rtk-users

_______________________________________________
Rtk-users mailing list
Rtk-users@public.kitware.com
https://public.kitware.com/mailman/listinfo/rtk-users

Reply via email to