Hi Lotte,
I had a very quick look at what you are doing. It looks fine to me, you
just need to perform way more iterations in the SIRT case. 100 would be
a good start. SIRT is more stable than SART when there are
inconsistencies in the projection data, but converges slowly.
An alternative to SIRT, which minimizes the same cost function with a
faster algorithm, is the conjugate gradient algorithm. You should obtain
nice results with something like 30-40 iterations (look for
rtk::ConjugateGradientConeBeamReconstructionFilter if you want to give
it a try).
Best regards,
Cyril
On 18/07/2017 11:17, Lotte Schyns wrote:
Hello,
We are having problems with the SIRT reconstructions. They seem very
strange and blurry. However, other reconstructions (SART, FDK,
iterativeFDK) look perfect. I uploaded an example of a SART and a SIRT
reconstruction (same parameters) to
https://www.dropbox.com/sh/7a4bkyjg43zjmy7/AAAp4tJrk9HedMEEuIKsGYDSa?dl=0.
I also uploaded a minimalistic version of the code that I used (the
paths in CMakeLists.txt probably need to be adapted to your system). You
can alternate between SART and SIRT by changing line 143. The raw data
is also available on dropbox. I didn't use
rtkXRadRawToAttenuationImageFilter, because our projections are already
corrected for the dark field and flood field, so
(signal-dark)/(flood-dark). I just take the natural logarithm and
multiply by -1. Do you know what could be the problem with the SIRT
reconstructions? Are we using wrong parameters? Thanks for your time.
Lotte
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