<div dir="ltr"><div>Hi,</div><div>I can see two problems:</div><div><span id="m_-6567014690663206133gmail-cwos">- you need to indicate the short scan to rtksimulatedgeometry, e.g. --arc 273 or, if the angle convention is opposite in your system, --arc -273. You may have to tune the --first_angle option to position the volume as you wish but that should not prevent accurate reconstruction.<br></span></div><div>- you need to center your projections, i.e., add the option --neworigin=<span id="m_-6567014690663206133gmail-cwos">-153.5985,</span><span id="m_-6567014690663206133gmail-cwos">-153.2025,0 to rtkfdk, computed with </span>-0.5*(3104-1)*0.099 and -0.5*(3096-1)*0.099.</div><div><span id="m_-6567014690663206133gmail-cwos">Don't hesitate to share a dataset if that does not help.</span></div><div><span id="m_-6567014690663206133gmail-cwos">Good luck!</span></div><div><span id="m_-6567014690663206133gmail-cwos">Simon<br></span></div><div><span id="m_-6567014690663206133gmail-cwos"><br></span></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, May 30, 2024 at 6:58 AM Christian Riesch <<a href="mailto:christian.riesch@live.com" target="_blank">christian.riesch@live.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>
<div lang="DE">
<div>
<p class="MsoNormal"><span lang="EN-US">Hello,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></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.<u></u><u></u></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" target="_blank">
https://tomroelandts.com/articles/astra-toolbox-tutorial-reconstruction-from-projection-images-part-1</a><u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">I have these parameters from the X-ray device that captured the images (size 3104x3096):<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"> "fod_mm": 75.46, (focus to object distance)<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"> "odd_mm": 407.07, (object to detector distance)<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"> "pixel_size_mm": 0.099,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"> "start_arc_deg": 45.0,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"> "stop_arc_deg": -45.0<u></u><u></u></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.)<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">So I have tried to create a geometry using<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">.\rtksimulatedgeometry.exe -o"geo.xml" -n91 -f45 -a90 --sdd=482.53 --sid=75.46<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">where sdd = fod_mm + odd_mm and sid = fod_mm,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">and a reconstruction with<u></u><u></u></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<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></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.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">For comparison, here are the input parameters for the Astra script:<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">distance_source_origin = 75.46 # [mm]<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">distance_origin_detector = 407.07 # [mm]<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">detector_pixel_size = 0.099 # [mm]<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">num_projections = 91<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">start_angle_deg = 45<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">stop_angle_deg = 135<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Any pointers would be appreciated.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Christian Riesch<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
</div>
_______________________________________________<br>
Rtk-users mailing list<br>
<a href="mailto:rtk-users@openrtk.org" target="_blank">rtk-users@openrtk.org</a><br>
<a href="https://www.creatis.insa-lyon.fr/mailman/listinfo/rtk-users" rel="noreferrer" target="_blank">https://www.creatis.insa-lyon.fr/mailman/listinfo/rtk-users</a><br>
</div></blockquote></div>