[vtkusers] Rotate vtkImage with vtkmatrix4x4

[David Gobbi]

Hi Jothy,

If you work with sagittal and coronal image you will have to worry about
image orientation, but with axial images everything is identity.

For axial images, just make sure that your camera ViewUp is (0, -1, 0)
and DirectionOfProjection is (0, 0, 1).  The direction of projection for
the camera is the (FocalPoint - Position) direction.

 - David


On Tue, Mar 1, 2011 at 10:36 AM, Jothy <jothybasu at gmail.com> wrote:
> Hi David,
>
> I have given up using vtkImageViewer2 right from the beginign of this
> project!
>
> Since it has problem with actors with varying z position - if your actors
> are from cutter ( some go behind the viewer).I am using vtkImageActor with
> vtkImageMapToColors and vtkImageReslice.
>
> The match between the dose and CT is perfect, except the view is upside
> down.
>
> So you mean there is no point in setting rotation and instead use the camera
> orientation.
>
> Thanks
>
> Jothy
>
> On Tue, Mar 1, 2011 at 5:26 PM, David Gobbi <david.gobbi at gmail.com> wrote:
>>
>> Hi Jothy,
>>
>> If your ImageOrientationPatient is 1 0 0 0 1 0 then the direction
>> cosines will be the identity matrix.
>>
>> So the image is fine, my guess is that vtkImageViewer2 is the
>> problem.  As I've said in other emails, I never use vtkImageViewer2.
>> But digging into its code, I see this:
>>
>>      case vtkImageViewer2::SLICE_ORIENTATION_XY:
>>        cam->SetFocalPoint(0,0,0);
>>        cam->SetPosition(0,0,1); // -1 if medical ?
>>        cam->SetViewUp(0,1,0);
>>        break;
>>
>> This view orientation is NOT the proper axial orientation for
>> DICOM patient coordinates.  In DICOM, Y increases in the
>> A-P direction (top-down), but vtkImageViewer2 has Y increase
>> from bottom to top.
>>
>> I suggest that you give up on vtkImageViewer2.  As I've said
>> before, I always use vtkImageActor to display images, and I
>> set the camera orientation myself.  And I use FileLowerLeftOn.
>>
>> And it is moot now, but the math here is incorrect:
>>  reslice->SetElement(0,3,IPP[0]);
>>  reslice->SetElement(1,3,IPP[1]);
>>  reslice->SetElement(2,3,IPP[2]);
>>
>> This applies a translation by IPP after the rotation, which is
>> not the same thing as rotating about IPP.
>>
>>  - David
>>
>>
>>
>> On Tue, Mar 1, 2011 at 9:58 AM, Jothy <jothybasu at gmail.com> wrote:
>> > Yes it doesn't rotate at all!
>> >
>> > My axial elements were
>> >
>> > reslice->DeepCopy( imageReader->GetDirectionCosines());
>> > reslice->SetElement(0,3,IPP[0]);
>> > reslice->SetElement(1,3,IPP[1]);
>> > reslice->SetElement(2,3,IPP[2]);
>> >
>> > My images have
>> >
>> > Image position: -275 -524 -122.441
>> > Image Dims: 512 512 98
>> > Image Origin: -275 -524 -122.441
>> > ImageOrient: 1 0 -1.22465e-16 0 1 0
>> >
>> >
>> >
>> >
>> >
>> > But this is changing only the y axis (some translation in Y). But no
>> > rotation.
>> >
>> > Any help is greatly appreciated.
>> >
>> > Thanks again
>> >
>> > Jothy
>> >
>> > On Tue, Mar 1, 2011 at 4:42 PM, David Gobbi <david.gobbi at gmail.com>
>> > wrote:
>> >>
>> >> Hi Jothy,
>> >>
>> >> When you say "doesn't rotate the image", do you mean that it does
>> >> nothing at all?  What are the elements of your direction cosines
>> >> matrix?
>> >>
>> >> Also, note that direction cosines matrix is a pure rotation matrix.
>> >> i.e. it rotates about (0,0,0).  You need to create a matrix that
>> >> rotates around a particular point in space.
>> >>
>> >>  - David
>> >>
>> >>
>> >> On Tue, Mar 1, 2011 at 9:28 AM, Jothy <jothybasu at gmail.com> wrote:
>> >> > Thanks!
>> >> >
>> >> > Now my images appeasr like the one shown in figure.
>> >> >
>> >> > I need to rotate the image and dose about the ImagePositionPatient
>> >> > upside-down.
>> >> >
>> >> > I tried vtkImageFlip - it invalidates the dicom coordinate system and
>> >> > the
>> >> > dose and image doesn't match.
>> >> >
>> >> > I tried this
>> >> >
>> >> >       vtkMatrix4x4 *invert = vtkMatrix4x4::New();
>> >> >
>> >> >         invert->DeepCopy( imageReader->GetDirectionCosines());
>> >> >
>> >> >         invert->Invert();
>> >> >
>> >> >         vtkImageReslice *reslice = vtkImageReslice::New();
>> >> >
>> >> >         reslice->SetResliceAxes( invert );
>> >> >
>> >> >         reslice->SetInput(this->imageData);
>> >> >
>> >> >         reslice->Update();
>> >> >
>> >> >
>> >> > But it doesn't rotate the image.How to rotate the image?
>> >> >
>> >> > Thanks
>> >> >
>> >> > Jothy
>> >> >
>> >> >
>> >> > On Tue, Mar 1, 2011 at 4:07 PM, Jothy <jothybasu at gmail.com> wrote:
>> >> >>
>> >> >> But in this example FileLowerLeft is switched off.
>> >> >>
>> >> >> Thanks
>> >> >>
>> >> >> Jothy
>> >> >>
>> >> >> On Tue, Mar 1, 2011 at 3:50 PM, Mathieu Malaterre
>> >> >> <mathieu.malaterre at gmail.com> wrote:
>> >> >>>
>> >> >>> jothy, I think what you are looking for is already in gdcm, have a
>> >> >>> look
>> >> >>> at:
>> >> >>> gdcmreslice.cxx
>> >> >>>
>> >> >>> hth
>> >> >>> On Tue, Mar 1, 2011 at 4:31 PM, Jothy <jothybasu at gmail.com> wrote:
>> >> >>> > Hi all,
>> >> >>> >
>> >> >>> > I am trying to rotate vtkImageData using vtkMatrix4x4 about a
>> >> >>> > point.
>> >> >>> > is
>> >> >>> > there any example on how to do this?
>> >> >>> >
>> >> >>> > Thanks
>> >> >>> >
>> >> >>> > Jothy
>> >> >>> >
>> >> >>> > _______________________________________________
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>> >> >>>
>> >> >>>
>> >> >>>
>> >> >>> --
>> >> >>> Mathieu
>> >> >>
>> >> >
>> >> >
>> >> > _______________________________________________
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