[Rtk-users] Parker weighting

[Simon Rit]

So calling AddProjection before and after the loop with an adequate
gantry_angle should work.
Simon

On Tue, Dec 8, 2015 at 9:52 AM, Shiras Abdurahman <shiraska at gmail.com>
wrote:

> Drear Simon,
>
> I generate the geometry with system geometry parameters and using
> AddProjection method.
>
> Here is the code
>
>
> rtk::ThreeDCircularProjectionGeometry::Pointer rtk_sys_geometry_;
> rtk_sys_geometry_ = rtk::ThreeDCircularProjectionGeometry::New();
> for (uint16_t proj_index = 0; proj_index < num_projections_; proj_index++)
> {
> rtk_sys_geometry_->AddProjection(rtk_geom_params_.at(proj_index).sid_mm,
> rtk_geom_params_.at(proj_index).sdd_mm,
> rtk_geom_params_.at(proj_index).gantry_angle_deg,
> rtk_geom_params_.at(proj_index).proj_offset_x_mm,
> rtk_geom_params_.at(proj_index).proj_offset_y_mm,
> rtk_geom_params_.at(proj_index).out_plane_angle_deg,
> rtk_geom_params_.at(proj_index).in_plane_angle_deg,
> rtk_geom_params_.at(proj_index).src_offset_x_mm,
> rtk_geom_params_.at(proj_index).src_offset_y_mm);
> }
>
>  And then write to xml file.
>
> Shiras
>
>
>
> On Tue, Dec 8, 2015 at 9:23 AM, Simon Rit <simon.rit at creatis.insa-lyon.fr>
> wrote:
>
>> Hi,
>> rtkfdk.cxx just read the geometry from a file so the best is to modify
>> the geometry file. How do you generate the geometry?
>> For example, if you use rtksimulated geometry, let's say that you were
>> using:
>> rtksimulatedgeometry -n 200 -a 200 -o g.xml
>> then you'll have to replace it with
>> rtksimulatedgeometry -n 202 -a 202 -o g.xml -f -1
>> Don't forget to add dummy projection at the beginning and the end. If you
>> use a more complex geometry, maybe SimpleRTK
>> <http://wiki.openrtk.org/index.php?title=SimpleRTK> can be helpful (I'd
>> use that) or you'd have to modify the cxx code to add these additional
>> projections in the geometry and the projection stack.
>> Simon
>>
>>
>> On Tue, Dec 8, 2015 at 8:51 AM, Shiras Abdurahman <shiraska at gmail.com>
>> wrote:
>>
>>> Dear Simon,
>>>
>>> Thanks a lot for the reply. Can you please inform me how can I set where
>>> the arc starts?
>>> Do I need to modify geometry also?
>>> If you can point the line of code rtkfdk.cxx, it will be really helpful.
>>>
>>> With regards,
>>> Shiras
>>>
>>> On Tue, Dec 8, 2015 at 7:56 AM, Simon Rit <
>>> simon.rit at creatis.insa-lyon.fr> wrote:
>>>
>>>> Dear Shiras,
>>>> Yes, for practical reasons the first and the last projections are set
>>>> to 0 and the arc used in the Parker weighting starts between the first two
>>>> projections and ends between the lasts two projections. There is a simple
>>>> solution: add a projection at the beginning and the end of the arc, which
>>>> can contain any pixel values but should be set where you want this arc to
>>>> start. In the future, I think someone should once take the time to correct
>>>> this but I haven't so far. I'll keep you posted on the mailing list when
>>>> it's corrected.
>>>> Simon
>>>>
>>>> On 07/12/2015 12:04, Shiras Abdurahman wrote:
>>>>
>>>> Hi all,
>>>>
>>>> I am trying to reconstruct a volume from projection data generated with
>>>> C-arm CT. There are 248 projections with an angular range of 199 degree.
>>>> Technically, parker weighting should run without any problems. However, I
>>>> am getting an output message that "You do not have enough data for proper
>>>> parker weighting". After parker weighting, the two extreme projections
>>>> (projection number 1 and 248) were completely zero and thus reconstructed
>>>> volume contained artifacts. When I increased the angular range, this
>>>> problem did not happen. How can I solve this problem without increasing
>>>> angular range? Is there any threshold constant that I can change in command
>>>> line  or in my code?
>>>>
>>>> I really appreciate any help you can provide.
>>>>
>>>> With regards,
>>>> Shiras
>>>>
>>>>
>>>> _______________________________________________
>>>> Rtk-users mailing listRtk-users at public.kitware.comhttp://public.kitware.com/mailman/listinfo/rtk-users
>>>>
>>>>
>>>>
>>>
>>
>
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