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
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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
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