<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>Hi Simon, </p>
<p>thank you very much for your quick reply. Your analysis was
correct, I needed to redefine the center.</p>
<p>I wish you a very nice day,</p>
<p>best regards,</p>
<p>Vincent<br>
</p>
<p><br>
</p>
<br>
<div class="moz-cite-prefix">On 2018-10-01 20:43, Simon Rit wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAF0oig2yFh5+J_5YwJu2s3=DZDGWX_otdHE_YZ_3vUYN-QM+kQ@mail.gmail.com">
<div dir="ltr">
<div>Hi Vincent,</div>
<div>This generally occurs when your detector offset is not
adequately passed to the geometry. When you say that you have
"5.2mm and -8mm" offsets, I guess it is with respect to a
centered geometry, where the central ray hits the detector.
For this to be the case in RTK, you must check that the
coordinate (0,0) mm corresponds to the center of the detector.
By default, I guess that tif puts it in the corner. So you
probably need to add to rtkprojections an option like
--neworigin xorig,yorig,0 where xorig and yorig is something
like -0.5*(npixels-1)*spacing.</div>
<div>If that doesn't help, you don't need to share the data, the
mhd headers are sufficient to test the geometry.</div>
<div>Good luck!</div>
<div>Simon<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr">On Mon, Oct 1, 2018 at 5:13 PM vincent <<a
href="mailto:vl@xris.eu" moz-do-not-send="true">vl@xris.eu</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi everyone,<br>
<br>
I am facing a problem when I try to reconstruct an object.
I'll try to <br>
be as complete as possible in the description.<br>
<br>
I acquired 18000 views from a custom-made ct scanner, of which
I <br>
extracted 360 for the sake of reconstruction speed for my
tests. The <br>
images are cropped to 1001*1761 pixels. An external
calibration program <br>
estimated that the x and y detector offsets where 5.2mm and
-8mm <br>
respectively. The sdd and sid are 983mm and 483mm. I used
those value <br>
to generate a simulated geometry.<br>
<br>
I then created a projection volume with the command<br>
<br>
rtkprojections -v -o rec1Proj.mha -p . -r cropped.*.tif --i0
7000 where <br>
I estimated the i0 value on the images background (for the
sake of <br>
completeness, I also tested with the automatic value which
resulted in <br>
the same problem)<br>
<br>
Finally, I wanted to reconstruct the volume with the command<br>
<br>
rtkfdk -g geoCT.xml -p . -r rec1Proj.mha --spacing 0.2
--dimension <br>
1761,1761,1761 -v -o recFDK.mha --hardware cuda<br>
<br>
<br>
The exact error message is:<br>
<br>
Reconstructing and writing... ExceptionObject caught with <br>
writer->Update() in file <br>
~/IPTools/RTK/RTK/applications/rtkfdk/rtkfdk.cxx line 218<br>
<br>
itk::ExceptionObject (0x1cf4b90)<br>
Location: "unknown"<br>
File:
~/IPTools/RTK/RTK/code/rtkDisplacedDetectorImageFilter.hxx<br>
Line: 155<br>
Description: itk::ERROR: Cannot account for detector
displacement larger <br>
than 50% of panel size. Corner inf=2.55504 and corner
sup=100.826<br>
<br>
I had a look at the aforementionned line in the <br>
rtkDisplacedDetectorImageFilter.hxx file but I didn't really
understand <br>
how the corners are computed in the <br>
inputPtr->TransformIndexToPhysicalPoint(inputPtr->GetLargestPossibleRegion().GetIndex(),
<br>
corner function.<br>
<br>
I have no problem sharing the projections if needed, but they
weight 1.3 <br>
Go altogether.<br>
<br>
<br>
I thank you very much in advance for any kind of help you can
provide.<br>
<br>
Best regards,<br>
<br>
Vincent<br>
<br>
<br>
_______________________________________________<br>
Rtk-users mailing list<br>
<a href="mailto:Rtk-users@public.kitware.com" target="_blank"
moz-do-not-send="true">Rtk-users@public.kitware.com</a><br>
<a
href="https://public.kitware.com/mailman/listinfo/rtk-users"
rel="noreferrer" target="_blank" moz-do-not-send="true">https://public.kitware.com/mailman/listinfo/rtk-users</a><br>
</blockquote>
</div>
</blockquote>
<br>
</body>
</html>