[Rtk-users] scanner development problems

[Simon Rit]

Hi,
I think it's a geometry problem. I don't have a solution for you but just a
remark: how did you come up with the neworigin parameter? Changing this has
a similar effect as changing the --proj_iso_x or "offseting" the
projections. And it seems that the value you put (-18.137) makes no sense
to me wrt the total width (800*0.0296=23.68). Typically, I center the
projection which in your case would require as a new origin 799/-2*0.0296.
I hope this helps,
Simon

On Wed, Mar 16, 2016 at 1:11 PM, Vasiliy Nabokov <nabokajeleboka at gmail.com>
wrote:

> Hi dear RTK users. Sorry, its offtop post... i just wanna tell you about
> my problems if anyone can help me..
> I develop scanner. Reconstruction of parallelepiped or cube (
> http://i.imgur.com/9YHyfWH.jpg) caused to phantom artifact (
> http://i.imgur.com/yyI184j.png). Don't look at noise, its test scan,
> without averaging and big rotation step.  Yea, it seems that its mainly
> misalignments problems, so i calibrated sourceX, sourceY, detectorX,
> detectorY by the following method
> http://www1.jinr.ru/Pepan_letters/panl_2015_5/10_gongad.pdf, got sourceX
> = -215 mkm, sourceY = 650 mkm, detectorX = 50mkm. i specify this
> information but without success.
>
> I also wrote a little program in this way
>     for (float sourceXOffset_ = sourceXFrom; sourceXOffset_ < sourceXTo;
> sourceXOffset_ += searchStep)
>     for (float sourceYOffset_ = sourceYFrom; sourceYOffset_ < sourceYTo;
> sourceYOffset_ += searchStep)
>     for (float projXOffset = projXFrom; projXOffset < projXTo; projXOffset
> += searchStep)
>     {
>         sprintf(cmd, "./rtksimulatedgeometry -o geometry.xml --n 90
> --arc=360 --sdd=232.241 --sid=170 --source_x=%.6f --source_y=%.6f
> --proj_iso_x=%.6f", sourceXOffset_, sourceYOffset_, projXOffset);
>
>         int r = system(cmd);
>
>         sprintf(cmd, "./rtkfdk --hardware=cuda -p /home/fee/Public/ -r
> [0-9]+.tif$ -o dump/out.mha -g geometry.xml --verbose --dimension 800,1,800
> --spacing 0.0296 --newspacing 0.0148 --neworigin -18.137,-12.128,0
> --subsetsize=1 -l --origin -11.8252,-3.55,-11.8252");
>         r = system(cmd);
> ...
>
> to search scanner alignment but also without success.
>
> I noticed interesting thing: when i specially offset detector horizontally
> to the right by 4.5mm from the center, and specify it by --proj_iso_x=4.5
> when generating geometry file, phantom disappears! (
> http://i.imgur.com/OOsPsfL.png) I even take scans when the detector on
> the center, reconstruct it, and here is phantom artifact, then i manually
> offset picture to the left on the tifs (from
> http://i.imgur.com/FGxCJUo.png to http://i.imgur.com/brbp5sd.png), and it
> reconstructs without phantom with --proj_iso_x=4.5! So, for this moment i
> work in this way, take scans when detector on the center, manually offset
> picture to the left and specify it by proj_iso_x to avoid phantom artifact,
> but its HUGE WORKAROUND =))
>
>
> What do you think about it ? If its geometry issue, why real or virtual
> offset of detector cleans up the phantom artifact?
>
>
> _______________________________________________
> Rtk-users mailing list
> Rtk-users at public.kitware.com
> http://public.kitware.com/mailman/listinfo/rtk-users
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/rtk-users/attachments/20160316/6a7c022b/attachment-0010.html>