<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Hello Simon,</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Thanks for the quick response.</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
So I have tried rtksimulatedgeometry with --arc 273 together with adding --neworigin=-153.5985,-153.2025,0 to rtkfdk.</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
The result is different than before, but still looks very wrong (two ribbons and some vertical lines).</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I may be able to share some data later.</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Best regards,</div>
<div class="elementToProof" style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Christian</div>
<div id="appendonsend"></div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<hr style="display: inline-block; width: 98%;">
<div id="divRplyFwdMsg" dir="ltr"><span style="font-family: Calibri, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><b>Von:</b> Simon Rit <simon.rit@creatis.insa-lyon.fr><br>
<b>Gesendet:</b> Donnerstag, 30. Mai 2024 08:48<br>
<b>An:</b> Christian Riesch <christian.riesch@live.com><br>
<b>Cc:</b> rtk-users@openrtk.org <rtk-users@openrtk.org><br>
<b>Betreff:</b> Re: [Rtk-users] Reconstruction geometry</span>
<div> </div>
</div>
<div style="direction: ltr;">Hi,</div>
<div style="direction: ltr;">I can see two problems:</div>
<div style="direction: ltr;">- 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.</div>
<div style="direction: ltr;">- you need to center your projections, i.e., add the option --neworigin=-153.5985,-153.2025,0 to rtkfdk, computed with -0.5*(3104-1)*0.099 and -0.5*(3096-1)*0.099.</div>
<div style="direction: ltr;">Don't hesitate to share a dataset if that does not help.</div>
<div style="direction: ltr;">Good luck!</div>
<div style="direction: ltr;">Simon</div>
<div style="direction: ltr;"><br>
</div>
<br>
<div style="direction: ltr;">On Thu, May 30, 2024 at 6:58 AM Christian Riesch <<a href="mailto:christian.riesch@live.com" id="OWAce49ae47-c33d-4707-5d97-0b1b5b798a8c" class="OWAAutoLink">christian.riesch@live.com</a>> wrote:</div>
<blockquote style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left: 1px solid rgb(204, 204, 204);">
<p>Hello,</p>
<p> </p>
<p>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.</p>
<p>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" id="OWA541d403d-3e31-4fc9-218d-6dd000ba5aa6" class="OWAAutoLink" data-auth="NotApplicable" style="margin-top: 0px; margin-bottom: 0px;">
https://tomroelandts.com/articles/astra-toolbox-tutorial-reconstruction-from-projection-images-part-1</a></p>
<p> </p>
<p>I have these parameters from the X-ray device that captured the images (size 3104x3096):</p>
<p> "fod_mm": 75.46, (focus to object distance)</p>
<p> "odd_mm": 407.07, (object to detector distance)</p>
<p> "pixel_size_mm": 0.099,</p>
<p> "start_arc_deg": 45.0,</p>
<p> "stop_arc_deg": -45.0</p>
<p>(There is also "detector_offset_mm": 9.8, which I have ignored so far with both Astra and RTK.)</p>
<p> </p>
<p>So I have tried to create a geometry using</p>
<p>.\rtksimulatedgeometry.exe -o"geo.xml" -n91 -f45 -a90 --sdd=482.53 --sid=75.46</p>
<p>where sdd = fod_mm + odd_mm and sid = fod_mm,</p>
<p>and a reconstruction with</p>
<p>.\rtkfdk.exe -p"images" -r".*tif" -g"geo.xml" -o"out.tif" --dimension=512,512,200 --newspacing=0.099</p>
<p> </p>
<p>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.</p>
<p> </p>
<p>For comparison, here are the input parameters for the Astra script:</p>
<p>distance_source_origin = 75.46 # [mm]</p>
<p>distance_origin_detector = 407.07 # [mm]</p>
<p>detector_pixel_size = 0.099 # [mm]</p>
<p>num_projections = 91</p>
<p>start_angle_deg = 45</p>
<p>stop_angle_deg = 135</p>
<p> </p>
<p>Any pointers would be appreciated.</p>
<p> </p>
<p>Best regards,</p>
<p>Christian Riesch</p>
<p> </p>
_______________________________________________<br>
Rtk-users mailing list<br>
<a href="mailto:rtk-users@openrtk.org" id="OWAb72ae54c-54f6-877f-1ad0-0bcb13aaffa6" class="OWAAutoLink">rtk-users@openrtk.org</a><br>
<a href="https://www.creatis.insa-lyon.fr/mailman/listinfo/rtk-users" id="OWA5436db22-01fa-c30a-c94e-eba3a0a88720" class="OWAAutoLink" data-auth="NotApplicable">https://www.creatis.insa-lyon.fr/mailman/listinfo/rtk-users</a><br>
</blockquote>
</body>
</html>