That did the trick.<br><br>For people that might be interested:<br><br> float angleX, angleY, angleZ;<br> angleX = angleY = angleZ = 5;<br><br> const double cx = vcl_cos(angleX);<br> const double sx = vcl_sin(angleX);<br>
<br> typedef itk::Matrix<double,3,3> Matrix;<br> Matrix RotationX;<br> Matrix FinalRotation = image->GetDirection();<br><br> RotationX[0][0] = 1; RotationX[0][1] = 0; RotationX[0][2] = 0; <br> RotationX[1][0] = 0; RotationX[1][1] = cx; RotationX[1][2] = sx; <br>
RotationX[2][0] = 0; RotationX[2][1] = -sx; RotationX[2][2] = cx;<br><br> FinalRotation = direction*RotationX;<br><br> std::cout << "image->GetDirection(): " << std::endl << image->GetDirection() << std::endl;<br>
std::cout << "RotationX: " << std::endl << RotationX << std::endl;<br> std::cout << "FinalRotation: " << std::endl << FinalRotation << std::endl;<br>
<br>
image->SetDirection(FinalRotation);<br><br> std::cout << "image->GetDirection(): " << std::endl << image->GetDirection() << std::endl;<br><br>produces this output:<br><br>image->GetDirection(): <br>
1 0 0<br>0 1 0<br>0 0 1<br><br>RotationX: <br>1 0 0<br>0 0.283662 -0.958924<br>0 0.958924 0.283662<br><br>FinalRotation: <br>1 0 0<br>0 0.283662 -0.958924<br>0 0.958924 0.283662<br>
<br>
image->GetDirection(): <br>1 0 0<br>0 0.283662 -0.958924<br>0 0.958924 0.283662<br><br><br>cheers, Michael<br><br><br><div class="gmail_quote">On Tue, Mar 30, 2010 at 11:14 AM, michiel mentink <span dir="ltr"><<a href="mailto:michael.mentink@st-hughs.ox.ac.uk">michael.mentink@st-hughs.ox.ac.uk</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Dear Luis,<br><br>thank you for your reply, now I understand what is meant!<br><br>Direction is from an image:<br>
<br> const ImageType::DirectionType & direction = image->GetDirection();<br><br>I'm trying to rotate the image by just changing the direction matrix of the image.<br>
<br>Unfortunately, when I just leave out 'const' from that line, the compiler complains<br>that it's not the same type as expected.<br><br>Maybe I should just create a new matrix, copy the value of image->GetDirection()<br>
into it, apply the rotation, and use image->SetDirection()?<br><br>cheers, Michael<div><div></div><div class="h5"><br><br><br><div class="gmail_quote">On Mon, Mar 29, 2010 at 11:04 PM, Luis Ibanez <span dir="ltr"><<a href="mailto:luis.ibanez@kitware.com" target="_blank">luis.ibanez@kitware.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi Michiel,<br>
<br>
<br>
It is excellent that you are diving into the code<br>
looking for deeper understanding !<br>
<br>
<br>
The message that you get indicates that you are<br>
attempting to change the value of a variable that<br>
has been declared "const" previously.<br>
<br>
The "const" declaration is a promise made to the<br>
compiler, stating that you will not change the value<br>
of that variable.<br>
<br>
When the compiler catch you breaking that promise,<br>
it get angry at you and gives you the error message:<br>
<br>
"error: passing ‘const X to Z discards qualifiers"<br>
<br>
<br>
Where the "qualifier" refers to the "const" property<br>
of that variable.<br>
<br>
<br>
The error message indicates that you are calling<br>
the operator=() method on a const matrix (as left<br>
argument of the = ).<br>
<br>
<br>
You did so, with an expression such as:<br>
<br>
<br>
const MatrixType myConstMatrixThatWillNeverChange;<br>
<br>
myConstMatrixThatWillNeverChange = anotherMatrix;<br>
<br>
<br>
This may also happens implicitly if the matrix<br>
happens to be a member variable of a class,<br>
and you attempt to do such assignment inside<br>
a "const" method of the class.<br>
<br>
<br>
If you share with use the exact declaration of your<br>
"direction" matrix we could tell you more about how<br>
to get around the problem.<br>
<br>
<br>
Regards,<br>
<br>
<br>
Luis<br>
<br>
<br>
<br>
--------------------------------------------------------------------------<br>
<div><div></div><div>On Mon, Mar 29, 2010 at 12:01 PM, michiel mentink<br>
<<a href="mailto:michael.mentink@st-hughs.ox.ac.uk" target="_blank">michael.mentink@st-hughs.ox.ac.uk</a>> wrote:<br>
><br>
> In an autodidactic effort, I'm trying to rotate an image by 'hand', by<br>
> multiplying the 'direction' matrix of an image by a rotation matrix.<br>
><br>
> To do that, I'm copying bits out of itkEuler3DTransform.txx<br>
> In that file, a RotationX matrix is defined:<br>
><br>
> Matrix<TScalarType,3,3> RotationX<br>
><br>
> However, when I try doing that, I'm getting the following error:<br>
><br>
> error: passing ‘const itk::Matrix<double, 3u, 3u>’ as ‘this’ argument of<br>
> ‘const itk::Matrix<T, NRows, NColumns>& itk::Matrix<T, NRows,<br>
> NColumns>::operator=(const itk::Matrix<T, NRows, NColumns>&) [with T =<br>
> double, unsigned int NRows = 3u, unsigned int NColumns = 3u]’ discards<br>
> qualifiers<br>
><br>
> 1) What does this mean?<br>
> 2) How do I get my beloved Matrix?<br>
><br>
> #include <itkMatrix.h><br>
> #include <vnl/vnl_matrix.h><br>
><br>
> typedef itk::Matrix<double,3,3> Matrix;<br>
><br>
> Matrix RotationX;<br>
> // ImageType::DirectionType RotationX;<br>
><br>
> // vnl_matrix_fixed<double,3,3> RotationX;<br>
><br>
> RotationX[0][0] = 1; RotationX[0][1] = 0; RotationX[0][2] = 0;<br>
> RotationX[1][0] = 0; RotationX[1][1] = cx; RotationX[1][2] = sx;<br>
> RotationX[2][0] = 0; RotationX[2][1] = -sx; RotationX[2][2] = cx;<br>
><br>
> direction = direction*RotationX;<br>
><br>
> cheers,<br>
><br>
> Michael<br>
><br>
><br>
><br>
><br>
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