[Rtk-users] Issue report regarding the recorder of Time elapsed

[Guangming Zang]

Hi Simon,
Thanks for your reply.
would you pls help and explain why backprojection is expected to take
shorter time than forward projection?? because i was thinking if no caching
step, the backprojection should take much longer time than sart algorithm.
yes, i run rtksart for 2 times once.it took 12xxs, similar to the time
consumed of 3 times's sart, which much slower than my own application.
BTW, D drive is local disk drive, and 360pro_SL_Vol128_512.mha are 360
shapp-logan projections(512*512 resolution each)
rtksart  -p . -r 360pro_SL_Vol128_512.mha  -g geometry.xml -o
../Result_SL512/SART_SL3.mha   -f Joseph -b VoxelBasedBackProjection
--newspacing 0.5  --dimension 128,128,128  --spacing 1,1,1  --origin
-64,-64,-64 -l 0.5 -n 3  --time 1

and i will try reader->Update() like what you said.
Thanks
Guangming



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




2015-07-27 8:59 GMT+03:00 Simon Rit <simon.rit at creatis.insa-lyon.fr>:

> Hi Guangming,
> It's not surprising to me that the backprojection is faster than the
> forward projection, that's what I expect. If the total time is longer,
> that's probably that some individual steps are not included in the total
> time. Can you try to add
> reader->Update();
> before the line
>
> itk::TimeProbe totalTimeProbe;
>
> in rtksart.cxx? It may be that all the reading operations are done but not timed in the sart->Update(). Why they are so long, I don't know, is your D: drive a network drive? Do you observe the same behavior if you do rtksart 2 times in a row?
>
> Simon
>
>
>
> On Mon, Jul 27, 2015 at 12:30 AM, Guangming Zang <
> guangming.zang at kaust.edu.sa> wrote:
>
>> Hi RTK community,
>> i am using SART algorithm to reconstruct an object.
>> But in this new RTK version, the time recording seems a little weird:
>>  the total time is 1219.12s , but adding the time cost in different
>> stages is not 1291.12 s. especially for "backprojection" part, only
>> 16.6051s to reconstruct a 128^3 volume ?? even shorter than forward
>> projection part. BTW, the -f and -b are Joseph and
>> VoxelBasedBackProjection, respectively, both multi-threading  i think.
>> Can anyone tell me what's going on?
>> Thanks
>> Regards
>> Guangming
>>
>> [image: 内嵌图片 1]
>> *Guangming Zang (Alex)*
>> *King Abdullah University of Science and Technology(KAUST)*
>> *University of Chinese Academy of Sciences(UCAS)*
>>
>>
>>
>>
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