[Rtk-users] Simulating geometric error on detector

[Vincent Libertiaux]

Hi Chang,

I was faced with the same problem not long ago. Here is the solution 
that worked for me:

If we call this extra angle "c", the following modifications have to be 
made in rtksimulatedgeometry:

- first angle = c

- sdd = sdd_0 * cos(c)

- sid = sid_0 * cos(c)

- source_x = source_x0 - sid*sin(c)

- proj_iso_x = proj_iso_x0 + (sdd-sid)*sin(c)

Hope it helps !

Best regards,

Vincent

On 27.11.22 22:44, gameboy514 at gmail.com wrote:
>
> Dear,
>
> Thank you for your reply, but I still have a question.
>
> I am trying to use Rtksimulatedgeometry which employs Addprojection. 
> It supports in_angle and out_angle, which is clear.
>
> There is also a parameter for gantry angle, but it does not seem that 
> simulation of slant can be done by simply changing the gantry angle.
>
> Left side of the figure is the schematic of simulation that I want 
> which only slants the detector.
>
> But if I perform the simulation as you suggest, the result that I will 
> get would be like the right side of the figure.
>
> To my understanding, the results of these two are not the same. (Slant 
> degree itself is same, but in the perspective of distance reaching to 
> side of the detector, it would be different.)
>
> It would be appreciated to help me to simulate only the slant of the 
> detector.
>
> Regards,
>
> Chang.
>
> *From:*Simon Rit <simon.rit at creatis.insa-lyon.fr>
> *Sent:* Friday, November 25, 2022 7:49 PM
> *To:* 김창환<gameboy514 at gmail.com>
> *Cc:* rtk-users at public.kitware.com
> *Subject:* Re: [Rtk-users] Simulating geometric error on detector
>
> Hi,
>
> There are three rotations to chose the orientation of the detector: 
> GantryAngle, InPlaneAngle and OutOfPlane. Any orientation can be set. 
> If you want a slant around the detector center, then a change in the 
> GantryAngle will imply a change in SourceToIsocenter, SourceToDetector 
> (both measured in the direction orthogonal to the detector) and 
> SourceOffsetX / ProjectionOffsetX. The geometry documentation should help:
>
> http://www.openrtk.org/Doxygen/DocGeo3D.html
>
> If you mind find it to set one detector position by setting the source 
> position, detector origin position and the u and v axes. See all the 
> different versions of AddProjection in the doxygen 
> <http://www.openrtk.org/Doxygen/classrtk_1_1ThreeDCircularProjectionGeometry.html>.
>
> Best regards,
>
> Simon
>
> On Fri, Nov 25, 2022 at 10:21 AM 김창환<gameboy514 at gmail.com> wrote:
>
>     Dear all,
>
>     I am now generating the simulation data with geometric distortions
>     on the detector, by using RTK.
>
>     Translation can be easily implemented by adjusting the parameters
>     (proj_iso_x and proj_iso_y).
>
>     However, for the rotation, it seems that there are only two
>     parameters I can manage. (in_angle and out_angle).
>
>     Thus, at this moment, tilt and skew are available to implement,
>     but for the slant, it seems that there is no such way.
>
>     Please let me know if there is any way to implement rotation about
>     one other axis.
>
>     (Image from Wang, Zhao, et al. "Improvements in micro-CT method
>     for characterizing x-ray monocapillary optics." /Optics
>     Communications/ 504 (2022): 127474.)
>
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