[vtkusers] Rotate vtkImage with vtkmatrix4x4

David Gobbi david.gobbi at gmail.com
Tue Mar 1 13:10:05 EST 2011 

About contours appearing behind the image... I forgot to comment on that.
Look at the documentation for vtkMapper::SetResolveCoincidentTopology()
to see how to make actors appear in front of the image.

Another trick is to apply vtkTubeFilter after vtkCutter, in order to give your
contour lines a finite thickness.

 - David


On Tue, Mar 1, 2011 at 10:45 AM, David Gobbi <david.gobbi at gmail.com> wrote:
> 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
>>> >> >>> >
>>> >> >>> > _______________________________________________
>>> >> >>> > Powered by www.kitware.com
>>> >> >>> >
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>>> >> >>> >
>>> >> >>> > Please keep messages on-topic and check the VTK FAQ at:
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>>> >> >>> >
>>> >> >>>
>>> >> >>>
>>> >> >>>
>>> >> >>> --
>>> >> >>> Mathieu
>>> >> >>
>>> >> >
>>> >> >
>>> >> > _______________________________________________
>>> >> > Powered by www.kitware.com
>>> >> >
>>> >> > Visit other Kitware open-source projects at
>>> >> > http://www.kitware.com/opensource/opensource.html
>>> >> >
>>> >> > Please keep messages on-topic and check the VTK FAQ at:
>>> >> > http://www.vtk.org/Wiki/VTK_FAQ
>>> >> >
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>>> >> >
>>> >
>>> >
>>
>>
>

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