[Rtk-users] Problem reconstructing from synthetic data

[Simon Rit]

Hi Albert,
Nice to hear that you are still working on CT. There are two things that
must be accounted for
- there is a difference in convention for the rotation angle between
gVirtualXRay and RTK,
- the projections are not centered if the origin is 0.
The following command lines work for me:
rtksimulatedgeometry -n 360 -a -360 -o g  --sdd 1000 --sid 500
rtkfdk -p . -r 'projection([0-9]*).tif' -o fdk.mha --neworigin
-159.75,-119.75,0 --newspacing 0.5 --nsort --submatch 1 --hardware cuda -g g
Let me know if something is unclear,
Simon

On Wed, Jun 21, 2023 at 10:04 AM Albert MURIENNE <Albert.MURIENNE at b-com.com>
wrote:

> Hello,
>
> I'm struggling to reconstruct properly a synthetic projection images
> sequence using RTK.
> The sequence was generated using gVirtualXRay (
> https://gvirtualxray.fpvidal.net/) and a dragon 3D model, and represents
> a full 360 degrees CBCT tomographic sequence, with a 500mm SID and 1000mm
> SDD, 0.5mm pixel size with a 640x480 image resolution, and without any
> offsets (perfect circular geometry). I tried reconstructions with the
> simplest FDK and SART implementations, inspired by RTK provided code
> examples, using rtk::ProjectionsReader to read the images and
> rtk::ThreeDCircularProjectionGeometry to read the geometry, but the results
> are not good, and I don't really know if the problem comes from the data or
> from my reconstruction implementation.
>
> The images data, as well as the xml geometry I generated, are available
> for download at this link:
>
>
> https://filesender.renater.fr/?s=download&token=bc8f87b4-989c-46d7-8c4b-dac39a4df0e1
>
> Could you help me pinpoint the origin of my problem? Does it come from the
> data itself?
>
> Thanks,
>
> Albert
> Murienne
>
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