[Rtk-users] SimpleRTK : help for defining a correct json file for CudaBackProjectionImageFilter

[Simon Rit]

No it doesn't, it's voxel based. The adjoint which uses the step size is
CudaRayCastBackProjectionImageFilter
<http://www.openrtk.org/Doxygen/classrtk_1_1CudaRayCastBackProjectionImageFilter.html>
but it's very slow and we never use it in practice because it's not
practical. When we want to use adjoint operators, we mainly use the CPU
version, with double precision when adjointness is very important.
Simon

On Fri, Dec 22, 2017 at 11:31 PM, Yannick Boursier <boursier at cppm.in2p3.fr>
wrote:

> Hi Simon,
>
> Thank you a lot for your answer, I will try to put the step size to the
> voxel size then (if I understand well). It seems that the implementation of
> the CudaBackProjectionImageFilter doesn't use any stepsize. I'll let you
> know.
>
> Merry Christmas to you,
> Yannick
>
> Le 22/12/2017 à 22:55, Simon Rit a écrit :
>
> Hi Yannick,
> I would just try to change the step size
> <http://www.openrtk.org/Doxygen/classrtk_1_1CudaForwardProjectionImageFilter.html#a93671bae5219bada43b9a00b6046dbed>.
> Indeed, the CPU version is the Joseph projector and it adapts automatically
> the step size to each ray for bilinear interpolation in each slice. The GPU
> version is a fixed step size combined with a trilinear interpolation.
> Merry Christmas to you,
> Simon
>
> On Fri, Dec 22, 2017 at 9:17 PM, Yannick Boursier <boursier at cppm.in2p3.fr>
> wrote:
>
>> Hi Cyril,
>>
>> Sorry for my late answer. First thank you because your last trick
>> (removing <InpuImageType>) worked, I correctly compiled and installed
>> everything.
>>
>> I am late because I thought that I did something wrong since when I
>> tested the code by simply projecting then backprojecting a simple volume,
>> the results between the CPU-codes and GPU-codes were different and the GPU
>> result cas clearly wrong.
>>
>> I understood this morning the problem and put it in evidence : the
>> CudaForwardProjectionImageFilter seems to be not adapted to the case
>> when the size of voxels and pixels are not equal to 1 whereas the
>> CudaBackProjectionImageFilter is OK for that !!
>>
>> I will try to debug it and let you know.
>>
>> I wish to all of you a Merry Christmas and relaxing holidays.
>>
>> Best ,
>>
>> Yannick
>>
>> Le 18/12/2017 à 16:52, Cyril Mory a écrit :
>>
>> Hi again Yannick,
>>
>> Simply removing the <InputImageType> on line 9 of your .json file made it
>> compile. I didn't test it yet. Let us know if that works for you.
>>
>> Cyril
>>
>> On 18/12/2017 16:31, Cyril Mory wrote:
>>
>> Hi Yannick,
>>
>> You seem to be in a hurry, so I'll start with an incomplete answer: the
>> CudaForwardProjectionImageFilter is templated over its input and output
>> image type, but the CudaBackProjectionImageFilter isn't (compare
>> rtkCudaForwardProjectionImageFilter.h and rtkCudaBackProjectionImageFilter.h,
>> there is not "template <>" before the class definition in ...Back..., while
>> it is there in ...Forward...).
>> I'm trying to modify your .json file accordingly, recompile and test, but
>> I never use SimpleRTK myself, so you might find the solution before I do.
>> If so, please report back on this mailing list.
>>
>> Cyril
>>
>>
>> On 18/12/2017 16:07, Yannick BOURSIER wrote:
>>
>> Hello all,
>>
>> I really need in "relative" emergency to execute the kernel CudaBackProjectionImageFilter using the Python Wrapper provided by SimpleRTK.
>> Unfortunately, this is not implemented in cuda (CudaForwardProjectionImageFilter is but not the BackProjection).
>>
>> I tried to define a json file (in attachement) on the base of CudaForwardProjectionImageFilter (since all the h, hxx, cxx, files I looked at seemed to be the same for these two kernels) but it does not compile (cmake instruction OK but not the make instruction) with the following error :
>>
>> /data/boursier/Compile/rtk-bin-extended/SimpleRTK-build/Code/BasicFilters/src/srtkCudaBackProjectionImageFilter.cxx: In member function ‘rtk::simple::Image rtk::simple::CudaBackProjectionImageFilter::ExecuteInternal(const rtk::simple::Image&, const rtk::simple::Image&)’:
>> /data/boursier/Compile/rtk-bin-extended/SimpleRTK-build/Code/BasicFilters/src/srtkCudaBackProjectionImageFilter.cxx:132:16: error: ‘rtk::CudaBackProjectionImageFilter’ is not a template
>>    typedef rtk::CudaBackProjectionImageFilter<InputImageType> FilterType;
>>
>> I would very much appreciate some help please because at this point, I have no idea about the problem...
>> Thanks in advance,
>> Best regards,
>> Yannick Boursier
>>
>>
>>
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