[Rtk-users] Insufficient Data For Proper Parker Weighting

[Simon Rit]

Hi,
I have finally taken the time to reproduce and correct for the bug, see
https://github.com/SimonRit/RTK/pull/380.
Sorry for the delay...
Simon

On Tue, Jun 30, 2020 at 6:45 AM Brani Rusanov <brani_rusanov at hotmail.com>
wrote:

> Sorry I forgot to mention, the Parker message only appears when
> reconstructing with CUDA enabled.
>
> ------------------------------
> *From:* Simon Rit <simon.rit at creatis.insa-lyon.fr>
> *Sent:* Tuesday, 30 June 2020 5:22 AM
> *To:* Brani Rusanov <brani_rusanov at hotmail.com>
> *Cc:* rtk-users at public.kitware.com <rtk-users at public.kitware.com>
> *Subject:* Re: [Rtk-users] Insufficient Data For Proper Parker Weighting
>
> Hi,
> No, I don't really understand what you're describing. It's probably easier
> if you can share the RTK geometry file and the header of your projection
> images (no need to share the data, I'll simulate some).
> Thanks,
> Simon
>
> On Mon, Jun 29, 2020 at 5:51 AM Brani Rusanov <brani_rusanov at hotmail.com>
> wrote:
>
> Hi Simon,
>
> Sorry for the late reply, I have been quite busy recently.
> My projections are 1024x768. I cropped the largest dimension and noticed
> that "half the beam angle" value decreases slightly, gets close to the
> value 9.951, but with further reduction in dimension size the beam angle
> suddenly jumps to ~20 degrees (observed value during reconstruction). So
> cropping the projection does not seem to solve the problem. Do you have any
> ideas how to fix this?
>
> If you require any geometry or projection files, I would be happy to send
> them over.
>
> Kind regards,
> Brani
> ------------------------------
> *From:* Simon Rit <simon.rit at creatis.insa-lyon.fr>
> *Sent:* Monday, June 15, 2020 8:59:19 PM
> *To:* Brani Rusanov <Brani_Rusanov at hotmail.com>
> *Cc:* rtk-users at public.kitware.com <rtk-users at public.kitware.com>
> *Subject:* Re: [Rtk-users] Insufficient Data For Proper Parker Weighting
>
> Hi,
> You are getting this because RTK detects that the scan is too short.
> Parker weighting requires pi + the fan-angle to be able to reconstruct
> exactly the central slice of your scan. Check here
> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FSimonRit%2FRTK%2Fblob%2Fmaster%2Finclude%2FrtkParkerShortScanImageFilter.hxx%23L139&data=02%7C01%7C%7Cdd34d79ef19149c0573e08d81c72539c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637290624638730119&sdata=ULmc3xlN2%2FTJlHJpo%2FYGvVLVayVbnewu8r%2B%2FrhVD6Ew%3D&reserved=0>
> how this is calculated in RTK.
> Possible solutions are cropping the projections to reduce the fan angle.
> I'm not sure what are the consequences but they'll probably be small since
> not much is missing in your case. It's even likely that RTK could be
> improved by discretizing differently the integral in parker weighting, in
> which case you'd get enough projections.
> Simon
>
>
> On Mon, Jun 15, 2020 at 10:56 AM Brani Rusanov <Brani_Rusanov at hotmail.com>
> wrote:
>
>
> Hi,
>
> I am attempting to reconstruct Varian raw cone-beam data. The specific
> type of scan is a short scan, 200 degrees generating 501 projections.
> During reconstruction I get the message: “you do not have enough data for
> proper Parker weighting (short scan) Delta is 9.951 degrees and should be
> more than half the beam angle I.e. 11.2359 degrees.”
>
> Since I have not generated the geometry myself, rather, used a pre-set
> Varian protocol, I am unsure why I get this error.
>
> How could I rectify this issue? Furthermore, what consequences are there
> to not applying a Parker weighting?
>
> The geometry header is attached.
>
> Your response is greatly appreciated,
> Brani
> _______________________________________________
> Rtk-users mailing list
> Rtk-users at public.kitware.com
> https://public.kitware.com/mailman/listinfo/rtk-users
> <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpublic.kitware.com%2Fmailman%2Flistinfo%2Frtk-users&data=02%7C01%7C%7Cdd34d79ef19149c0573e08d81c72539c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637290624638740143&sdata=rfrMAQf4nej0oPrbyDcIHHLvGGTVDUQaL1aqW7BnleE%3D&reserved=0>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://public.kitware.com/pipermail/rtk-users/attachments/20201006/f82a328e/attachment.htm>