Thank you for your quick replies! The rtkinlinefdk application is very interesting. I have read it and have two observations:
1. The Parker short scan code is currently disabled in that application. I guess the reason is that it cannot compute the overscan angle without the full geometry, and that it has to be provided in some other way than through the geometry object. 2. The reconstruction processing starts when there are at least 3 projections available (line 281), and it then starts with the second projection. The reason for this (I suppose) is that the angular gaps are computed based on adjacent projection angles, so projection angles 0 and 2 needs to be available to properly weight projection 1. Finally (line 343), the first (0) and last (N) projection are backprojected, which I suppose is because the angular gap between projection N and 0 should be available to the angular gap weighting of projections 0 and N. Typically the RTK Parker weighting puts 0 weight for first and last projection so that the very large angular gap weighting (e.g. for half scans) for first and last projection has no effect. (Line numbers relates to commit 4198eb3 of https://github.com/SimonRit/RTK) Are there any current plans or ideas on how to add support for inline Parker weighting (and allow e.g. half scans)? If not, what is the procedure for contributing to the RTK project with such a Parker weighting implementation? Best regards, Fredrik 343 2018-02-22 15:36 GMT+01:00 Simon Rit <simon....@creatis.insa-lyon.fr>: > Hi, > Yes, you can even if you don't know the geometry in advance. The > application rtkinlinefdk and its code rtkinlinefdk.cxx illustrates this. > Best regards, > Simon > > On Thu, Feb 22, 2018 at 2:05 PM, Chao Wu <wucha...@gmail.com> wrote: > >> Hi Fredrik, If the geometry and projection angles are known in advance, I >> think it is possible to perform FDK online. >> Regards, Chao >> >> 2018-02-22 11:11 GMT+01:00 Fredrik Hellman <fredrik.hell...@gmail.com>: >> >>> Hi, >>> >>> I am wondering if it is possible to do "online" reconstruction with RTK >>> using FDK backprojection, i.e. that you populate the geometry object angle >>> by angle and backproject only one or a few projections at a time with the >>> geometry object not fully populated initially. >>> >>> I have seen that the backprojection can be done projection by >>> projection, but it seems that the geometry object must be populated with >>> all angles before starting. For example in the code for parker weighting, >>> it seems that the overscan angle is estimated based on the actual angles in >>> the geometry object. Also, computing the angular gap weighting done in the >>> 2D weighting depends on adjacent angles. >>> >>> Best regards, >>> Fredrik Hellman >>> >>> _______________________________________________ >>> Rtk-users mailing list >>> 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 >> >> >
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