Hi Vincent (and Jasper), I agree with Jasper that this is most likely due to a difference in geometric calibration between the two datasets. Do you have more information on what does B use (projection matrices, detailed parametrization, etc.)? I think that such a blur can be caused by a difference in source to detector distance (or, equivalently, detector pixel size). Simon
On Tue, Apr 19, 2022 at 11:08 AM Vincent Libertiaux <v...@xris.eu> wrote: > On 16.04.22 13:52, Jasper Albertus Nijkamp wrote: > > Hi Vincent, > > > > From just these two images, it is a bit hard to help. However, I have > seen similar challenges when the detector vertical offset is not properly > set. If you could share a bit more data (fx projection data and the > geometry), more people might be able to help. > > > > Jasper > > > > -----Original Message----- > > From: Rtk-users <rtk-users-boun...@public.kitware.com> On Behalf Of > Vincent Libertiaux > > Sent: Friday, 15 April 2022 17:15 > > To: rtk-users <rtk-users@public.kitware.com> > > Cc: Damien Koch <d...@xris.eu> > > Subject: [Rtk-users] Lateral blur in a FDK reconstructed volume > > > > Hello rtk users ! > > > > I am facing a problem for which I have exhausted all the possibilities > except asking you. > > I have performed a standard FDK reconstruction of a lego bricks > assembly. I used a custom-made code to compute the detector horizontal > offset and tilt angle, found to be 1.15 mm and 0.02° respectively. The > result of the reconstruction is shown in the picture > > https://ibb.co/LdMzJF2 . The volume looks mostly sharp, except on the > lateral edges, let's say on the last half brick. > > > > We had the opportunity to have the same volume reconstructed with two > commercial solutions. The first one, "A", produced the same results than > rtk. The second, "B", produced the result shown in the picture > https://ibb.co/VwXMmRH > > > > In this case, the edges are sharp too. The offset values found with > this software were very close (1.13mm and 0.025° respectively) and feeding > them to rtksimulatedgeometry didn't change my result. No other correction > was allegedly applied. > > > > I thought that the edge blurring was due to a wobbling artefact but it > can't be the case according to the result with the "B" software. > > > > Do you have any idea on what could cause this blurring on the edges ? > > > > I thank you very much for any clue. > > > > Best regards, > > > > Vincent > > > > _______________________________________________ > > Rtk-users mailing list > > Rtk-users@public.kitware.com > > https://public.kitware.com/cgi-bin/mailman/listinfo/rtk-users > > Hi Jasper, > > thank you for your reply. I had already tried to play with the vertical > offset but setting it to a value different than 0 progressively decrease > the overall quality of the reconstruction. > Following your advice, here are the projections: > > http://share.xris.eu/d91b09673bba > > word of warning, the set is very large (900 projections on a 3072x3072 > pixels detector, approx. size = 16Go) I could try and make it smaller > by downsampling it but I am afraid it would mask the problem. I can try > and do it on request. > The geometric parameters I used were: SDD = 810 mm, SID = 410 mm, > proj_iso_x = 1.15mm and in_angle = 0.02°. > > > Best regards, > > Vincent > > _______________________________________________ > Rtk-users mailing list > Rtk-users@public.kitware.com > https://public.kitware.com/cgi-bin/mailman/listinfo/rtk-users > >
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