[Rtk-users] The result got from ADMMTV from shapp-logan generated from RTK

[Guangming Zang]

Hi Simon and Chao,

i am currently do some comparisons between different reconstruction methods
for Shapp-Logan dataset.

the commands are:

rtksimulatedgeometry -n 360 --arc -360 -o
geo.xml   --sdd=955.4050067  --sid=500.0

rtkprojectshepploganphantom -g geo.xml --phantomscale 64 -o proj.mha
--dimension 512,512



when using FDK or SART algorithm from RTK, I can got pretty good results
indeed(to see clearly, set contrast as [0.95,1.13], i.e., windows as 0.09
and levels as 1.04 for all results got). When running ADMMTV command below,
though the geometry is as same as SART and FDK, the result got from ADMM
looks weird.(pls see attached central slice of ground truth and ADMM, same
contrast with other algorithm)

rtkadmmtotalvariation -p . -r proj.mha  -g geo.xml -o
SL_ADMM_0.001_0.01.mha     --dimension 128,128,128 --spacing 1,1,1    -n 2
--CGiter 3 --origin -64,-64,-64 --alpha 0.001 --beta 0.01 --time 1

 [image: 内嵌图片 1][image: 内嵌图片 2]

Is it because the CG algorithm used by ADMM, or parameters setting issues
here?? if it is parameters setting problem , would you help me and give a
nice values for alpha and bate used here?

BTW, I had tried the –alpha from [0.001,1] and –bate[0.01,10] already
(including default value)

Thanks and regards

Guangming


​​
*Guangming Zang (Alex)*
*King Abdullah University of Science and Technology(KAUST)*
*University of Chinese Academy of Sciences(UCAS)*

​

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