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<p class="MsoNormal"><span lang="EN-US">Hello,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I'm currently trying to use RTK for a reconstruction from a stack of images that resulted from a 90° scan, but struggling to get the parameters right.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">On the other hand, I was able to get what looks like a faithful reconstruction using the Astra toolbox and the script from
<a href="https://tomroelandts.com/articles/astra-toolbox-tutorial-reconstruction-from-projection-images-part-1">
https://tomroelandts.com/articles/astra-toolbox-tutorial-reconstruction-from-projection-images-part-1</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I have these parameters from the X-ray device that captured the images (size 3104x3096):<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> "fod_mm": 75.46, (focus to object distance)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> "odd_mm": 407.07, (object to detector distance)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> "pixel_size_mm": 0.099,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> "start_arc_deg": 45.0,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> "stop_arc_deg": -45.0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">(There is also "detector_offset_mm": 9.8, which I have ignored so far with both Astra and RTK.)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">So I have tried to create a geometry using<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">.\rtksimulatedgeometry.exe -o"geo.xml" -n91 -f45 -a90 --sdd=482.53 --sid=75.46<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">where sdd = fod_mm + odd_mm and sid = fod_mm,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">and a reconstruction with<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">.\rtkfdk.exe -p"images" -r".*tif" -g"geo.xml" -o"out.tif" --dimension=512,512,200 --newspacing=0.099<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">However, out.tif contains mostly zeros and a weird ribbon-like shape in the center. So I think my geometry is wrong, but I don't know how to fix it.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">For comparison, here are the input parameters for the Astra script:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">distance_source_origin = 75.46 # [mm]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">distance_origin_detector = 407.07 # [mm]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">detector_pixel_size = 0.099 # [mm]<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">num_projections = 91<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">start_angle_deg = 45<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">stop_angle_deg = 135<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Any pointers would be appreciated.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Christian Riesch<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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