[Rtk-users] How to make the comparison?

[Chao Wu]

Hi Guangming,

Glad to see you get it work.

The size of the phantom is described in physical units (e.g. mm) in the txt
file. The spacing of the image file is also in physical units (mm) and the
dimension is in number of voxels. Therefore spacing * dimension gives you
the physical size of the image volume. That's why if you want to have the
same volume in mm^3 you need keep the spacing * dimension a constant.

If you want to have a 128^3 dimension spacing=1 SheppLogan phantom with the
*same* *content, not same physical size*, you are actually looking for a
smaller phantom: 128 * 1 is 1/4 of 256 * 2, so it is 4 times smaller in
length. You can get this phantom by changing the size description in the
txt file, or you can first create a dimension=128 but spacing=4 image file
and subsequently change the spacing from 4 to 1.

Regards,
Chao

2015-05-11 13:05 GMT+02:00 Guangming Zang <guangming.zang at kaust.edu.sa>:

>
>
> Hi Chao,
>
> Thanks for your help.
>
> Yes, it works. But I am still a little confused.
>
>  In the example in wiki,
> <http://wiki.openrtk.org/index.php/RTK/Examples/ADMMTVReconstruction>the
> only input for  command rtkdrawgeometricphantom  is SheppLogan.txt, in
> which , after I checked, the geometry information is not included. So I
> thought I can generated any size of volume as I want. (for example, 64^3
> volume dimension with spacing 1 or 1024^3 volume dimension with spacing 10)
> why should  the   dimension *spacing (1*512=2*256=512)   should be fixed as
> a  constant???
>
>
> Briefly speaking,my question is , by using command rtkadmmtotalvariation
> or rtkdrawgeometricphantom,
> how can i generated a 128^3 dimension SheppLogan volume with spacing as 1
> .  Is it possible for the SheppLogan.txt provided by this example  to make
> it  ???
>
> So could you help me to find the solution??
>
> Thanks for your help, Chao.
>
> With my best regards
>
> Guangming
>
> *Guangming Zang (Alex)*
> *King Abdullah University of Science and Technology(KAUST)*
> *University of Chinese Academy of Sciences(UCAS)*
>
>
>
>
> 2015-05-11 11:06 GMT+03:00 Chao Wu <wuchao04 at gmail.com>:
>
>> Hi Guangming,
>>
>> If you half the spacing you need twice the dimension (in length, or 8
>> times in volume) to cover the same area, i.e. --spacing 1 --dimension 512.
>> Is this what you want?
>>
>> Regards,
>> Chao
>>
>> 2015-05-10 22:50 GMT+02:00 Guangming Zang <guangming.zang at kaust.edu.sa>:
>>
>>> Hi all.
>>> I have implemented SART algorithm with some optimizations.and i wanna to
>>> make a comparison with the implementations in our RTK.
>>> My questions are:
>>> 1. how to use RTK to  generate the initial  volume(i.e., ground Truth
>>> )to make the comparison?
>>> 2. My answer to the question 1 is that maybe i can use rtkdrawgeometricphantom
>>> to generate a reference volume. However,
>>> I noticed that in  the ADMMTV example in RTK wiki page,
>>> <http://wiki.openrtk.org/index.php/RTK/Examples/ADMMTVReconstruction>
>>> when i use the default demand, it works well (both for rtkadmmtotalvariation
>>> and rtkdrawgeometricphantom)
>>> . But when i change the spacing from 2 to 1, and dimension as 128.
>>> i.e. the commands
>>> from
>>> rtkdrawgeometricphantom --spacing 2 --dimension 256--phantomfile
>>> SheppLogan.txt -o ref.mha
>>> to
>>>
>>> rtkdrawgeometricphantom --spacing 1 --dimension 128 --phantomfile SheppLogan.txt -o ref.mha
>>>
>>> the volume's visualization(ref.mha) is wired .
>>>
>>> So can you help me to find what's going on or tell me a better way to make the comparison between RTK method and my implementations.
>>>
>>>
>>> Thanks in advance and with my best regards
>>>
>>> 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.
>>> _______________________________________________
>>> Rtk-users mailing list
>>> Rtk-users at public.kitware.com
>>> http://public.kitware.com/mailman/listinfo/rtk-users
>>>
>>>
>>
>
> ------------------------------
> 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/20150511/e1dd0887/attachment-0009.html>