[vtkusers] vtkImageReslice axes direction, based on a vtkPlane

[David Gobbi]

I should also add that, for what you want to do, there is a better way
to do the 2D viewing with vtkImageSlice than calling
mapper->SetSlicePlane().   Instead, you could tell the mapper to
follow the camera, and then just set the camera to the view that you
want:

mapper = vtkImageResliceMapper::New();
mapper->SliceFacesCameraOn();
mapper->SliceAtFocalPointOn();

// x,y,z is the "origin" you used for vtkPlane,
// nx,ny,nz is the "normal" you used for vtkPlane
// d is the camera distance
camera->SetFocalPoint(x,y,z);
camera->SetPosition(x+d*nx, y+d*ny, z+d*nz);
renderer->ResetCameraClippingRange();

 - David

On Thu, Sep 22, 2011 at 9:20 AM, David Gobbi <david.gobbi at gmail.com> wrote:
> Hi Timjen,
>
> The vtkImageSlice class is a vtkProp3D, so the only way to view the
> slice like a 2D image is to move the camera into the right position.
> So you will need to write some code that will set the camera
> orientation from the normal of your plane.  It isn't that hard to do,
> just follow these steps:
>
> 1) call camera->ParallelProjectionOn(), you don't want perspective in a 2D view
> 2) call camera->SetParallelScale(100), use the image size in place of 100
> 3) call renderer->ResetCamera() to automatically set the camera focal point
> 4) use the following code to set the view:
>
> double focalPoint[3];
> double camPosition[3];
> double camDistance = camera->GetDistance();
> camera->GetFocalPoint(focalPoint);
> camPosition[0] = focalPoint[0] + camDistance*normal[0];
> camPosition[1] = focalPoint[1] + camDistance*normal[1];
> camPosition[2] = focalPoint[2] + camDistance*normal[2];
> camera->SetPosition(position);
> camera->SetViewUp(0,1,0); // whatever "up" should be
> renderer->ResetCameraClippingRange();
>
> Use SetParallelScale() to change the magnification and
> use SetViewUp() to change the rotation around the normal.
>
> The ResampleToScreenPixels() doesn't do what you think.
> It is just a quality setting.
>
> I can't answer about the vtkShader2 object, the slice rendering does
> not use shaders.
>
>  - David
>
>
> On Thu, Sep 22, 2011 at 5:03 AM, Tijmen Klein <T.R.Klein at student.rug.nl> wrote:
>> Hi David,
>> This is exactly what I was looking for, thank you! Got the newest VTK
>> version from git, compiled it and modified my program
>> (using http://vtk.org/gitweb?p=VTK.git;a=blob;f=Examples/ImageProcessing/Python/ImageInteractorReslice.py as
>> an example). vtkImageResliceMapper really makes a world of difference, and
>> makes the slicing a lot easier.
>> However, there is still one small issue for me. I would like to display this
>> slice as if it was a 2D image. Would you have an idea how to do this? If I
>> simply add the vtkImageSlice to my renderer, it shows up at the exact
>> location of the cut (which is to be expected). I could set the camera
>> position + focal point based on the origion and normal of the cutting plane,
>> but I would like the slice to fill the whole viewport. The
>> method  ResampleToScreenPixelsOn() seems to be designed to do this, using
>> this however does not change a thing for me.
>> Cheers,
>> Tijmen
>>
>> On Wed, Sep 21, 2011 at 5:06 PM, David Gobbi <david.gobbi at gmail.com> wrote:
>>>
>>> Hi Tijmen,
>>>
>>> If you are able to grab the devel version of VTK from git, your
>>> best option is to use the new image rendering classes:
>>> http://www.vtk.org/Wiki/VTK/Image_Rendering_Classes
>>> The vtkImageResliceMapper has a method called SetSlicePlane(),
>>> so all you have to do is set the image as the input, then set the
>>> plane you want to slice with.  The mapper will do everything else.
>>>
>>>  - David
>>>
>>>
>>> On Wed, Sep 21, 2011 at 3:42 AM, Tijmen Klein <T.R.Klein at student.rug.nl>
>>> wrote:
>>> > Hello Everyone,
>>> > I have a volume that I cut off using a vtkPlane
>>> > (volume->AddClippingPlane()), which works really well. But sometimes I
>>> > also
>>> > need to show to cut itself. First I tried to use a vtkCutter for this,
>>> > the
>>> > geometry of the output is fine, but the texture is incorrect.
>>> > So I'm now used a vtkImageReslice, which gives the desired output.
>>> > However,
>>> > the textured plane of the output does not always cover the whole area of
>>> > the
>>> > vtkCutter. For example, see this
>>> > image: http://dl.dropbox.com/u/27566470/slice_and_cut.png The red bar
>>> > indicates the geometry of the vtkCutter, the blue plane is the slice of
>>> > the
>>> > vtkImageReslice.
>>> > How can I make sure that the output of vtkImageReslice covers the whole
>>> > vtkCutter? I have the feeling that my current method is too complex. I
>>> > want
>>> > an output that is equal to the output of creating a slice in Paraview.
>>> > Cheers,
>>> > Tijmen
>>
>>
>