[Rtk-users] Can i force the voxel values of volume be constructed to be positive?

[Guangming Zang]

Hi Simon,
thanks for the explanation in detail.
​i can understand why​ there is only post-processing for fdk algorithm now,
but why don't we do the non-negative  checking during each ADMM iteration?
after all, in my opinion, in most of applications, only volume values that
between [0,positive infinite) make sense.
Regards
Guangming

*Guangming Zang (Alex)*
*King Abdullah University of Science and Technology(KAUST)*
*University of Chinese Academy of Sciences(UCAS)*




2015-08-06 8:27 GMT+03:00 Simon Rit <simon.rit at creatis.insa-lyon.fr>:

> Hi,
> No there is no option to force the output volume to 0. This is not the
> same as sart where you might want to do it during the iterations. In the
> FDK case, it's only post-processing so there is not really a reason to put
> it in rtkfdk.
> The nonneg option is the minimum value of the intensity that you allow the
> Boellaard algorithm to reach after scatter correction. This does not
> prevent negative values in the volume because the ramp filter might create
> negative values from positive projections.
> Simon
>
> On Thu, Aug 6, 2015 at 2:00 AM, Guangming Zang <
> guangming.zang at kaust.edu.sa> wrote:
>
>> Dear Simon and RTK community,
>> considering in rtksart ,we have --positivity to force the reconstructed
>> volume values to be positive(i guess, not tested yet), i was wondering if
>> we have any options and commands to have the same effect in algorithms fdk
>> and admmtv since --positivity can not be found?
>> the Boellaard scatter correction: --nonneg  is what i am looking for?
>> Thanks in advance.
>> Guangming
>> *Guangming Zang (Alex)*
>> *King Abdullah University of Science and Technology(KAUST)*
>> *University of Chinese Academy of Sciences(UCAS)*
>>
>>
>>
>>
>> ------------------------------
>> This message and its contents, including attachments are intended solely
>> for the original recipient. If you are not the intended recipient or have
>> received this message in error, please notify me immediately and delete
>> this message from your computer system. Any unauthorized use or
>> distribution is prohibited. Please consider the environment before printing
>> this email.
>
>
>

-- 

------------------------------
This message and its contents, including attachments are intended solely 
for the original recipient. If you are not the intended recipient or have 
received this message in error, please notify me immediately and delete 
this message from your computer system. Any unauthorized use or 
distribution is prohibited. Please consider the environment before printing 
this email.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/rtk-users/attachments/20150806/901275ef/attachment-0010.html>