[Insight-users] itkMatrix error: discards qualifiers??

[michiel mentink]

in
/itkEuler3DTransform.txx
the rotation is applied either in X Y Z order, or Z X Y order (standard),
where Y rotation is applied first.

Indeed, if I try different orders of rotation, I get different outcomes. I
suppose this is due to round-off
errors.
Why is Z X Y chosen as the standard way of multiplication?


Z Y X
image->GetDirection():
 0.999695   0.0171452 0.0177517
-0.0174497  0.999701  0.0171452
-0.0174524 -0.0174497 0.999695

X Y Z
image->GetDirection():
0.999695    0.0174497 0.0174524
-0.0177543  0.99969   0.0174497
-0.0171425 -0.0177543 0.999695

Z X Y
image->GetDirection():
 0.99969    0.0174497 0.0177543
-0.0177543  0.999695  0.0171425
-0.0174497 -0.0174524 0.999695

cheers,

Michael





On Tue, Mar 30, 2010 at 12:18 PM, michiel mentink <
michael.mentink at st-hughs.ox.ac.uk> wrote:

>
> ah just after posting I found it (figures!)
>
> complete and correct code now:
>
>
>   const ImageType::DirectionType & direction = image->GetDirection()
>   std::cout << "direction: " << std::endl << direction << std::endl <<
> std::endl;
>
>   float angleX, angleY, angleZ;
>   angleX = angleY = angleZ = 1  *   vnl_math::pi / 180.0;             // in
> this case: rotation = 1 degree
>
>
>   const double cx = vcl_cos(angleX);
>   const double sx = vcl_sin(angleX);
>
>   typedef itk::Matrix<double,3,3> Matrix;
>   Matrix RotationX;
>   Matrix FinalRotation = image->GetDirection();
>
>   std::cout << "sin: " << sx << " Cos: " << cx << std::endl;
>
>
>   RotationX[0][0] = 1; RotationX[0][1] =   0; RotationX[0][2] = 0;
>   RotationX[1][0] = 0; RotationX[1][1] =  cx; RotationX[1][2] = sx;
>   RotationX[2][0] = 0; RotationX[2][1] = -sx; RotationX[2][2] = cx;
>
>   FinalRotation = direction*RotationX;
>
>   std::cout << "image->GetDirection(): " << std::endl <<
> image->GetDirection() << std::endl;
>   std::cout << "RotationX: " << std::endl << RotationX << std::endl;
>   std::cout << "FinalRotation: " << std::endl << FinalRotation <<
> std::endl;
>
>   image->SetDirection(FinalRotation);
>
>   std::cout << "image->GetDirection(): " << std::endl <<
> image->GetDirection() << std::endl;
>
>
> cheers, Michael
>
>
>
>
>
>
> On Tue, Mar 30, 2010 at 12:10 PM, michiel mentink <
> michael.mentink at st-hughs.ox.ac.uk> wrote:
>
>> Hello Frederic,
>>
>> thanks for your suggestion.
>>
>> although my code was working, I tried your suggestion. Unfortunately, it
>> produces
>>
>> error: no match for ‘operator*’ in
>> ‘image.itk::SmartPointer<TObjectType>::operator-> [with TObjectType =
>> itk::Image<float, 3u>]()->itk::ImageBase<VImageDimension>::GetDirection
>> [with unsigned int VImageDimension = 3u] * RotationX’
>>
>>
>> Anyway, I forgot to mention to use:
>>
>>   float angleX, angleY, angleZ;
>>   angleX = angleY = angleZ = 1 * (3.14/180);
>>
>> (multiply by pi and divide by 180 degrees, because ITK internally works
>> with radians instead of degrees)
>>
>> Which leads me to the question: vnl has a pi constant, and I remember
>> vaguely having seen it somewhere as vnl::PI or something.
>> Does anyone know how to convince vnl to hand me pi constant?
>>
>> cheers, Michael
>>
>>
>>
>>
>> On Tue, Mar 30, 2010 at 11:55 AM, Frederic Perez <fredericpcx at gmail.com>wrote:
>>
>>> Hello Michiel,
>>>
>>> perhaps you could use a const Matrix object after all, since it looks to
>>> me that FinalRotation is first built with image->GetDirection() but this
>>> value is not actually used, and that the signature of itk::Image's is
>>> SetDirection(const DirectionType direction).
>>>
>>> So here you are, my quickly written proposal (caution, I haven't compiled
>>> it):
>>>
>>>   float angleX, angleY, angleZ;
>>>   angleX = angleY = angleZ = 5;
>>>
>>>   const double cx = vcl_cos(angleX);
>>>   const double sx = vcl_sin(angleX);
>>>
>>>   typedef itk::Matrix<double,3,3> Matrix;
>>>   Matrix RotationX;
>>>   // Matrix FinalRotation = image->GetDirection(); -- Commented now
>>>
>>>   RotationX[0][0] = 1; RotationX[0][1] =   0;  RotationX[0][2] = 0;
>>>   RotationX[1][0] = 0; RotationX[1][1] =  cx; RotationX[1][2] = sx;
>>>   RotationX[2][0] = 0; RotationX[2][1] = -sx; RotationX[2][2] = cx;
>>>
>>>   const Matrix FinalRotation = direction*RotationX;
>>>
>>>
>>>   std::cout << "image->GetDirection(): " << std::endl <<
>>> image->GetDirection() << std::endl;
>>>   std::cout << "RotationX: " << std::endl << RotationX << std::endl;
>>>   std::cout << "FinalRotation: " << std::endl << FinalRotation <<
>>> std::endl;
>>>
>>>   image->SetDirection(FinalRotation);
>>>
>>>   std::cout << "image->GetDirection(): " << std::endl <<
>>> image->GetDirection() << std::endl;
>>>
>>> Cheers,
>>>
>>> Frederic
>>>
>>>
>>
>
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