[Rtk-users] How to determine the position and size of reconstructed volume

[Deepak Roy Chittajallu]

Hello All,

I have at hand a stack of projection images and the projection geometry
defined in a .cal file of digisens. I am trying to use RTK to do the
reconstruction.

I used rtk::DigisensGeometryReader
<http://www.openrtk.org/Doxygen/classrtk_1_1DigisensGeometryReader.html> to
read the .cal file and generate the geometry.

Then i call rtk::FDKConeBeamReconstructionFilter
<http://www.openrtk.org/Doxygen/classrtk_1_1FDKConeBeamReconstructionFilter.html>
to
do the reconstruction by supplying to it as Inputs -- the geometry, a dummy
reference image of the reconstructed volume (with origin, spacing, size,
direction etc), and the stack of projection images.

But i am getting a blank volume as reconstruction.

I suspect the problem is with positioning the reconstructed volume
(specified via the dummy reference image).

As a sample attached is the digisens .cal file that RTK uses for testing
purposes which looks very similar to mine.

In lines 642-656, it seems to define the postion, size, and spacing of the
reconstructed volume via the following schema:

---------------------------------------------------------------------

 <Grid>
  <rotation>0 0 0.705858 0.708353</rotation>
  <center>-1.23119 -16.6554 10.2144</center>
  <scale>0.2 0.2 0.2</scale>
  <resolution>289 399 360</resolution>
  <autoRotation>true</autoRotation>
  <cylinderConstraint>false</cylinderConstraint>
  <cylinderConstraintFromGrid>false</cylinderConstraintFromGrid>
  <name>C:/Documents/2011_02_14_15-15-12_FenteAl/reconstruction.vol</name>
  <format>2</format>
  <beamHardening>0</beamHardening>
  <background>0</background>
  <colorscaling>1 0</colorscaling>
  <rawOutput></rawOutput>
 </Grid>

-----------------------------------------------------------------------

I understand the <scale> (spacing in mm) and <resolution> (size) elements.
These can be used to SetSize() and SetSpacing() of the dummy reconstructed
volume provided as input to the reconstruction filter.

I dont know how to translate the <rotation> and <center> to SetOrigin(),
and SetDirection() of the dummy reconstructed volume.

Does anyone know how to do this?

Or alternatively, is there a way to automatically set these to reconstruct
the maximum possible extent of the object positioned in between the source
and detector?

Regards,

Deepak
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/rtk-users/attachments/20160209/2e4ba922/attachment-0009.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: calibration.cal
Type: application/octet-stream
Size: 49220 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/rtk-users/attachments/20160209/2e4ba922/attachment-0009.obj>