[Rtk-users] Blurred piece-wise reconstruction

[vincent]

Hi Simon,

thank you very much for the quick reply.

I have some leads about my problem, I'll post the solution if I find 
it.  In the meantime, I tested the division option that went under my 
radar, I am afraid.

I am certainly doing something wrong or not understanding the mechanism 
of that option.  From what I understood from the code, the streamer will 
split the volume to be reconstructed in <dimensions> subset along the y 
axis, which is indeed exactly what I am looking for.  When I tried to 
use it, however, I got an error message, hereafter reproduced:

itk::MemoryAllocationError (0x7fbb04000940)
Location: "unknown"
File: 
/home/vincent/IPTools/InsightToolkit-5.0.1/Modules/Core/Common/include/itkImportImageContainer.hxx
Line: 199
Description: Failed to allocate memory for image.

The command line I used was

rtkfdk -p . -r projections.mhd --hardware cuda -o reconstruction.mhd -g 
rt900.xml --spacing 0.23 --dimension 2000 --divisions 4

I am using a NVIDIA GEForce-GTX 1080 TI with 11 Go of RAM and able to 
reconstruct a 1024*1024*1024 volume.

Could you please help me finding what I did wrong ?

Thank you again for your invaluable help,

kindest regards,

Vincent


On 11.02.20 17:36, Simon Rit wrote:
> Hi Vincent,
> There is a way to do such a thing in rtkfdk with the --divisions 
> option, see code here 
> <https://github.com/SimonRit/RTK/blob/master/applications/rtkfdk/rtkfdk.cxx#L190-L196>. 
>
> I also don't really understand either what's going on in your bottom 
> reconstruction, it seems to be a geometric problem. Have you checked 
> an axial slice?
> Simon
>
> On Tue, Feb 11, 2020 at 4:21 PM vincent <vl at xris.eu 
> <mailto:vl at xris.eu>> wrote:
>
>     Hello RTK community,
>
>     I am afraid that my question might not be directly related to the
>     excellent implementation we are all using, but it might still be
>     interesting for some of you.
>
>     I have a stack of 1500 projections of size 2048*2048.  I obviously
>     can't
>     reconstruct the full resolution volume on my graphics card, as it
>     is too
>     big.  So my solution was to split the sinogram into N parts, for
>     which
>     each reconstructed volume would fit in my GPU memory and then
>     reassemble
>     them.  I did a test with a 700*820*900 sinogram, that I cut in two
>     parts
>     of 700*410(+a small overlap)*900.
>
>     While the reconstruction of the whole volume was acceptable, I got a
>     weird issue with the split ones: the one corresponding to the top
>     of the
>     image is also ok, but the bottom one is very blurry.  The three
>     images
>     can be found at the following links:
>
>     https://ibb.co/vLk9ZhQ
>     https://ibb.co/m4pm0LT
>     https://ibb.co/Jyf1yKM
>
>     I used the same calibration parameters for the three
>     reconstruction.  I
>     visually checked the split sinograms and they looked fine.
>
>
>     Any insight will be much appreciated !
>
>
>     Thanks in advance,
>
>     kindest regards,
>
>     Vincent
>
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