Hi Shiras, I generated a volume to look at your problem: rtkdrawshepploganphantom --like volume.mhd -o volume.mhd --phantomscale 32 --offset 0,0,1.7 Then I obtained the same issue as you. I think the problem is that rtkfdk is meant for circular CBCT and it includes pre-weighting for displaced detector and short scan. I'm not sure why you don't get a warning but these are probably responsible for the blank output. A simple solution is to do only the 3 FDK steps using in order the command tools: rtktwodweights rtkramp rtkbackprojections You can also try to shunt the preweighting by modifying rtkfdk.cxx.
It's interesting that you try out tomosynthesis but you'll encounter some problem. When I ran the above commands, I get very weird results because the first and the last projections get a lot more weight than the others since it looks at the angular weight with the previous and the next projections. A simple solution is to blank out these two projections. Good luck and keep us posted if you get interesting results, Simon On Thu, May 19, 2016 at 10:41 AM, Shiras Abdurahman <[email protected]> wrote: > Dear all, > > I am trying to simulate Tomosynthesis reconstruction with stationary flat > panel detector where source rotates around Y axis to acquire 21 projections > (system geometry diagram is attached). Geometry file geometry.xml is > generated with Reg23ProjectionGeometry. I generated projection images of > a cube volume and then I tried to reconstruct with FDK algorithm. Even > though I am able to generate projections, FDK reconstruction yields the > volume with all voxel values zero. The commands I used for generating > projections and reconstructing volume are > > rtkforwardprojections -g geometry.xml -o projections.mhd -i volume.mhd > --spacing 0.1518,0.1518,1 --dimension 1420,1416,21 --fp=CudaRayCast > rtkfdk -p . -r projections.mhd -o fdk.mhd -g geometry.xml > --spacing=0.25,0.25,0.25 --origin=-31.875,-31.875,25 > --dimension=256,256,256 --hardware=cuda > > I am also attaching geometry xml file, mhd header files of the original > volume, projections and reconstructed volume. > > With regards, > Shiras > > > > _______________________________________________ > Rtk-users mailing list > [email protected] > http://public.kitware.com/mailman/listinfo/rtk-users > >
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