Hi, FYI, I have opened the images. As far as I can guess from the sequence, the circular trajectory of the source is very small wrt to the object size. I don't know what I would do from such a trajectory. I would start by checking the work in tomosynthesis to find some inspiration. Good luck! Simon
On Wed, Nov 1, 2017 at 10:22 AM, Robert Calliess <robert.calli...@gmx.de> wrote: > Hello, > > i’ve uploaded the projection images for the first trajectory. > > https://www.dropbox.com/s/rpcyemuvfngd4rw/QFN1.7z?dl=0 > > > > Inside the folder you can find the projection images. Furthermore you will > find > > two textfiles, positions.txt and calibration.txt. The positions.txt > contains the physical > > position of the detector center. Position id 35 is the orthogonal view. > All other projection ids > > are positions on a circular path around the center position 35. > > The calibration.txt contains the fod, odd and the physical detector size. > > All units given are in micrometers. > > > > Kind regards, > > Robert > > > > > > *Von:* Cyril Mory [mailto:cyril.m...@creatis.insa-lyon.fr] > *Gesendet:* Mittwoch, 25. Oktober 2017 09:34 > *An:* Robert Calließ > *Cc:* rtk-users@public.kitware.com > > *Betreff:* Re: [Rtk-users] FDK for planar ct > > > > Dear Robert, > > Could you send two datasets of projections, one for each case ? We would > have a look at them and it would help us understand your trajectories. The > drawings you sent do not seem to be sufficient to remove all ambiguities. > > Best regards, > > Cyril > > > > On 25/10/2017 09:03, "Robert Calließ" wrote: > > Hello, > > the object is moving on a circular path. There are arrows between the > different detector positions showing the > > moving direction. The source is static. > > > > Kind regards, > > Robert > > > > *Gesendet:* Dienstag, 24. Oktober 2017 um 16:47 Uhr > *Von:* "Simon Rit" <simon....@creatis.insa-lyon.fr> > <simon....@creatis.insa-lyon.fr> > *An:* "Robert Calließ" <robert.calli...@gmx.de> <robert.calli...@gmx.de> > *Cc:* "rtk-users@public.kitware.com" <rtk-users@public.kitware.com> > <rtk-users@public.kitware.com> <rtk-users@public.kitware.com> > *Betreff:* Re: Re: [Rtk-users] FDK for planar ct > > Hi, > > I see one drawing only, not two. And the object does not seem to be moving > on your drawing, is it? If not and the source is also static (as it seem), > this is equivalent to one large projection. > > Simon > > > > On Tue, Oct 24, 2017 at 3:58 PM, "Robert Calließ" <robert.calli...@gmx.de> > wrote: > > Hello, > > I suppose there are still misunderstandings with respect to the trajectory. > > Attached you can find the two difference trajectories. I also had a closer > look to > > the off centered fdk ( the paper you suggested). But I don't think it is > in my case. > > The iso ray passes object center and detector center at each view. Off > centered fdk > > has a different preweighting scheme. > > > > You said that the RTK ramp filter is along the u axis (orthogonal to > rotaion axis). For planar_ct_1 trajectory that > > should fit. As you can see at the picture, the object is moving on a > circular path but not rotating around the > > center point (red cross in the image). > > > > > > Kind regards, > > Robert C. > > > > *Gesendet:* Donnerstag, 12. Oktober 2017 um 07:14 Uhr > *Von:* "Simon Rit" <simon....@creatis.insa-lyon.fr> > *An:* "Robert Calliess" <robert.calli...@gmx.de> > *Cc:* "rtk-users@public.kitware.com" <rtk-users@public.kitware.com> > > > *Betreff:* Re: [Rtk-users] FDK for planar ct > > Hello, > > No. The filter should be orthogonal to the rotation axis. The RTK ramp > filter is along the u axis of the projection. > > Trajectory 2: if you take photos by rotating the cameras, they are > photographies of the same point-of-view. This is what I meant. > > Cheers, > > Simon > > > > On Wed, Oct 11, 2017 at 8:58 PM, Robert Calliess <robert.calli...@gmx.de> > wrote: > > Hello, > > thanks for the link to the paper but I dont have access to it. Aside from > how the trajectory is interpreted within in RTK. My actual question was > > if any of those two trajectories would need another reconstruction filter > than the FDK Filter. From my point of understanding a specific rotation > around > > the object is necessary for fbp/fdk (like c-arm bow, standard circular > cone-beam trajectory). That’s why I asked If the first trajectory needs > some other reconstruction > > filter because the object itself doesn’t rotate around itself. It actually > gets translated on a circular path. So I was more expecting a “yes” or “no” > to the fdk filter > > or a hint to another filter (except iterative reconstructions) I should > use for these trajectories. > > > > To trajectory 2: I think the projections are different. The object rotates > and each projection shows a different view. > > > > > > Kind regards, > > Robert C. > > > > *Von:* simon....@gmail.com [mailto:simon....@gmail.com] *Im Auftrag von *Simon > Rit > *Gesendet:* Dienstag, 10. Oktober 2017 20:29 > *An:* Robert Calliess > > > *Cc:* Cyril Mory; rtk-users@public.kitware.com > *Betreff:* Re: [Rtk-users] FDK for planar ct > > > > > > Hi, > > Let me try to clarify what I mean by "source trajectory wrt the object." > In tomography, you need to determine the source trajectory in the object > coordinate system, we don't really care about the source trajectory in the > room coordinate system. For example, rotating the source on a circular > trajectory or rotating the object makes no difference for the > reconstruction algorithm. That's why we call diagnostic scanners "helical > scanners". > > So for trajectory 1, it seems that the source trajectory (again, wrt to > the object) is a circle but the object is offset. This is somewhat similar > to https://doi.org/10.1109/TNS.2006.880977 except that the detector is > not tilted so FDK would be the only FBP algorithm I could think of. But the > situation is really not good, data are missing and iterative reconstruction > should give better results. > > Trajectory 2: what I said in my previous email is true, it's useless I > believe, all projections are similar up to a 2D transform of the projection. > > Simon > > > > On Tue, Oct 10, 2017 at 8:07 PM, Robert Calliess <robert.calli...@gmx.de> > wrote: > > Hello, > > I try to clarify the both trajectories. > > > > Trajectory 1: > > No, i dont move the source on two circles. The xray source is fixed. Only > the object and the detector moves. Both move on a circular path so that the > iso-ray > > always passes through the pcb centre and the detector centre. There is one > orthogonal view and the others are the ones moving on the circular path. > > (Object is not rotating around its own axis). > > > > Trajectory 2: > > Yes, the xray source lies in the rotation axis and only the object rotates > around its z-axis. Detector and xray source are fixed and the detector is > tilted. > > It’s almost like this trajectory here https://www.ikeda-shoponline. > com/engctsoft/wp-content/uploads/2016/06/Oblique-View-CT1.jpg > > except that the xray source lies on the rotation axis. > > > > I hope this helps to understand the trajectories I have to deal with. > > > > Kind regards, > > Robert > > > > > > *Von:* simon....@gmail.com [mailto:simon....@gmail.com] *Im Auftrag von *Simon > Rit > *Gesendet:* Dienstag, 10. Oktober 2017 19:06 > *An:* Robert Calließ > *Cc:* Cyril Mory; rtk-users@public.kitware.com > > > *Betreff:* Re: [Rtk-users] FDK for planar ct > > > > Hi, > > It's still not clear to me but what is helpful is to think in terms of > source trajectory wrt the object. > > Trajectory 1: if I understand, you move the source on two circles plus one > point. I don't know of a FBP algorithm to reconstruct this, but there might > be one. I would consider iterative reconstruction first. > > Trajectory 2: your trajectory is a point, the source does not move with > respect ot the object since it lies on the rotation axis. So each > projection contains exactly the same information up to a simple 2D > projection deformation. So it's hopeless to reconstruct from one projection > only. > > To create the correct geometry, I would suggest using the function > AddProjection > <https://github.com/SimonRit/RTK/blob/master/code/rtkThreeDCircularProjectionGeometry.h#L92> > for which you provide the source and detector positions plus the 3D > coordinates of the two axes of the coordinate system of the projection. > > I hope this helps > > Simon > > > > On Tue, Oct 10, 2017 at 5:43 PM, "Robert Calließ" <robert.calli...@gmx.de> > wrote: > > Hello, > > thank you for the fast reply. > > To answer your questions first. > > In this case the abbrevation pcb stands for printed circuit board. > > Next point is the trajectory we are currently handling with. > > Please see the attached image "trajectory.png". There are two schematics > showing the side view and top view for trajectory type 1 > > and a side-view for trajectory type 2. > > > > For type 1: > > The xray source is fixed. The pcb is clamped within a transport, so the > pcb and the detector are moveable with in the xy plane. > > As you can see at the image, the pcb moves along a circular path but the > pcb itself is not rotating. And let's assume that the iso ray > > always passes through the centre of the pcb and the centre of the detector. > > > > For type 2: > > The xray source is fixed and the detector is tilted. The pcb lies centred > in the middle of a table. So that the pcb rotates around its centre > > around the z-axis. > > > > > > I hope this makes clear what trajectory i'm dealing with. Thank you. > > > > Kind regards, > > Robert C. > > > > > > > > > > > > > > *Gesendet:* Dienstag, 10. Oktober 2017 um 15:31 Uhr > *Von:* "Cyril Mory" <cyril.m...@creatis.insa-lyon.fr> > *An:* "Robert Calliess" <robert.calli...@gmx.de>, > rtk-users@public.kitware.com > *Betreff:* Re: [Rtk-users] FDK for planar ct > > Dear Robert, > > Your description of the trajectory is very obscure to me. Maybe you have a > very unusual X-ray system. Could you make the following points clear : > > - what is a PCB ? > > - what is fixed/moving in your system (we need this information for the > object, the source and the detector), and what kind of trajectories have > the moving parts ? > > - can you re-draw your sketch with just 2 or 3 positions (ideally, on > similar but separate drawings), each one with the object, the source and > the detector ? > > If you do that, we should have a clear understanding of how your > acquisition goes, and be able to give you appropriate advice. > > Best regards, > > Cyril > > > > On 10/10/2017 15:02, Robert Calliess wrote: > > Hello rtk users, > > I have question to the RTK FDK Filter. As far as I understand from to the > fourier slice theorem the object to be reconstructed needs a circular > trajectory and needs to rotate its own centre. > > Please have a look at the attached sketch. With this planar trajectory > (Object, a PCB, is moved on a circle trajectpry “in-plane”, PCB itself is > not rotating) do I need > > a special filtering if I want to use FDK for planar CT with respect to the > sketched trajectory ? I tried a circular in-plane trajectory where the PCB > is centred and rotates > > around its centre point. And with 100 projections I get good results. But > with the trajectory I described (sketch, attached image) the results are > not so good. > > Because of the row-wise ramp filter It looks like there is a directional > dependency. My assumption is, and with respect to fourier slice theorem, > that the missing object > > rotation (rotation around itself) causes there directional effects. > > > > So my questions to the experts are. Do I need to apply a special filtering > before backprojecting with FDK or is it just the wrong > > algorithm for this kind of trajectory ? > > > > kind regards, > > Robert C. > > > > _______________________________________________ > > Rtk-users mailing list > > Rtk-users@public.kitware.com > > http://public.kitware.com/mailman/listinfo/rtk-users > > > _______________________________________________ > Rtk-users mailing list > Rtk-users@public.kitware.com > http://public.kitware.com/mailman/listinfo/rtk-users > > > > > > > > > _______________________________________________ > > Rtk-users mailing list > > Rtk-users@public.kitware.com > > http://public.kitware.com/mailman/listinfo/rtk-users > > > > _______________________________________________ > Rtk-users mailing list > Rtk-users@public.kitware.com > http://public.kitware.com/mailman/listinfo/rtk-users > >
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