[Rtk-users] Error message: cannot account for detector displacement larger than 50% of panel size

[vincent]

Hi everyone,

I am facing a problem when I try to reconstruct an object. I'll try to 
be as complete as possible in the description.

I acquired 18000 views from a custom-made ct scanner, of which I 
extracted 360 for the sake of reconstruction speed for my tests. The 
images are cropped to 1001*1761 pixels.  An external calibration program 
estimated that the x and y detector offsets where 5.2mm and -8mm 
respectively.  The sdd and sid are 983mm and 483mm.  I used those value 
to generate a simulated geometry.

I then created a projection volume with the command

rtkprojections -v  -o rec1Proj.mha -p . -r cropped.*.tif --i0 7000 where 
I estimated the i0 value on the images background (for the sake of 
completeness, I also tested with the automatic value which resulted in 
the same problem)

Finally, I wanted to reconstruct the volume with the command

rtkfdk  -g geoCT.xml -p . -r rec1Proj.mha  --spacing 0.2 --dimension 
1761,1761,1761 -v -o recFDK.mha  --hardware cuda


The exact error message is:

Reconstructing and writing... ExceptionObject caught with 
writer->Update() in file 
~/IPTools/RTK/RTK/applications/rtkfdk/rtkfdk.cxx line 218

itk::ExceptionObject (0x1cf4b90)
Location: "unknown"
File: ~/IPTools/RTK/RTK/code/rtkDisplacedDetectorImageFilter.hxx
Line: 155
Description: itk::ERROR: Cannot account for detector displacement larger 
than 50% of panel size. Corner inf=2.55504 and corner sup=100.826

I had a look at the aforementionned line in the 
rtkDisplacedDetectorImageFilter.hxx file but I didn't really understand 
how the corners are computed in the 
inputPtr->TransformIndexToPhysicalPoint(inputPtr->GetLargestPossibleRegion().GetIndex(), 
corner function.

I have no problem sharing the projections if needed, but they weight 1.3 
Go altogether.


I thank you very much in advance for any kind of help you can provide.

Best regards,

Vincent