[Rtk-users] geometry offsets

[Simon Rit]

Hi,
This is almost correct. I think the default origin is -127.5 in the second
case so the option of the first case should have been
"--origin=-27.5,-127.5". Then, there would have been no geometric
difference for RTK, it comes down to a choice between shifting the origin
of your image or setting a relative position of your image with respect to
the volume. Note that if you have different offsets for each projection,
only the second option is feasible.

In RTK, the center-of-rotation is always (0,0,0). So you have to shift the
rest if you want to shift it (source and detector position indeed).
Simon

On Mon, Apr 6, 2015 at 3:40 PM, bambykaa 1 <bambykaa at yandex.ru> wrote:

> Hello RTK users.
> Is there difference between this
> rtksimulatedgeometry -n 180 -o geometry.xml
> rtkprojectgeometricphantom -g geometry.xml -o projections.mha --spacing 1
> --dimension 256 --phantomfile SheppLogan.txt --origin=-28,-128
>
> and this
>
> rtksimulatedgeometry -n 180 -o geometry.xml  --proj_iso_x=100
> rtkprojectgeometricphantom -g geometry.xml -o projections.mha --spacing 1
> --dimension 256 --phantomfile SheppLogan.txt
>
> ?
>
> As i understand these sequences are identical and using for specifying
> detector offset.
>
> But if i want to specify iso center offset ? May be..
> rtksimulatedgeometry -n 180 -o geometry.xml --proj_iso_x=100 --source_x=100
> rtkprojectgeometricphantom -g geometry.xml -o projections.mha --spacing 1
> --dimension 256 --phantomfile SheppLogan.txt
> Is it right ?
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