Image Display on VTK Viewers

VTK provide two viewers:

·         1. vtkImageviewer2

·         2. vtkResliceImageViewer

vtkImageviewer2

· vtkImageviewer2 is convienient class for displaying 2D image sequence of a image volume. It replace earlier version of the class vtkImageviewer. vtkImageviewer2 encapsulates several objects

o    vtkRenderWindow

o    vtkRenderer

o    vtkImageActor

o    vtkImageMapToWindowLevelColors

This class also include vtkInteractorStyleImage that allow zooming, panning,Orientation(XY,YZ,XZ) and windowing.

It provide the function SetSlice() to change the image data(slice) on viewer.

There are two ways to use it:

·  vtkImageviewer2 *viewer= vtkImageviewer2::New();

viewer->SetInputConnection(reader->GetOutputPort());

viewer->SetSlice(40);

viewer->SetSliceOrientationToXY();

viewer->Render();

·  This is to add geometry and Image

viewer->SetInputConnection(reader->GetOutputPort());

viewer->GetRenderer()->AddActor(actor);

This is the sample code:

#include <vtkSmartPointer.h>

#include <vtkJPEGReader.h>

#include <vtkRenderer.h>

#include <vtkRenderWindowInteractor.h>

#include <vtkImageViewer2.h>

int main(int argc, char *argv[])

{     

vtkSmartPointer<vtkJPEGReader> reader=vtkSmartPointer<vtkJPEGReader>::New();

//SetFileName()for single file .Use SetFileNames for more than one file(This will cover in next blog with Qt)

reader->SetFileName("D:\\testing_Dataset\\JPEG "/*Dataset Path*/);    

reader->Update();

vtkSmartPointer<vtkImageViewer2>viewer=

vtkSmartPointer<vtkImageViewer2>::New();

vtkSmartPointer<vtkRenderWindowInteractor>interactor =vtkSmartPointer<vtkRenderWindowInteractor>::New();

interactor->SetRenderWindow( viewer->GetRenderWindow() ); 

viewer->SetupInteractor(interactor);

viewer->SetInputConnection(reader->GetOutputPort());

     

viewer->GetRenderer()->ResetCamera();

viewer->Render();

interactor->Start();

return  EXIT_SUCCESS;

}

vtkResliceImageViewer

This class is similar to vtkImageViewer2. It displays the image along with a two cross hairs for reslicing. The cross hairs may be interactively manipulated and are typically used to reslice two other views of vtkResliceImageViewer. This class has default behaviour of vtkImageViewer2 if the Reslice mode is set to RESLICE_AXIS_ALIGNED.This class provide default functionality for scrolling image data and automatic windowing. 

This is the sample code:

#include <vtkSmartPointer.h>

#include <vtkDICOMImageReader.h>

#include <vtkRenderer.h>

#include <vtkRenderWindowInteractor.h>

#include <vtkResliceImageViewer.h>

int main(int argc, char *argv[])

{

vtkSmartPointer<vtkDICOMImageReader> reader=vtkSmartPointer<vtkDICOMImageReader>::New();

reader->SetDirectoryName(("D:\\testing_Dataset\\DICOM "/*Directory Path*/);

reader->Update();

vtkSmartPointer<vtkResliceImageViewer>viewer  =vtkSmartPointer<vtkResliceImageViewer>::New();

vtkSmartPointer<vtkRenderWindowInteractor>interactor =vtkSmartPointer<vtkRenderWindowInteractor>::New();

interactor->SetRenderWindow( viewer->GetRenderWindow() );

viewer->SetupInteractor(interactor);

viewer->SetInputConnection(reader->GetOutputPort());

int  midslice =viewer->GetSliceMax()/2;

viewer->SetSlice(midslice);

viewer->SetSliceOrientationToXY();

viewer->GetRender er()->ResetCamera();

viewer->Render();

interactor->Start();

return  EXIT_SUCCESS;

}

NOTE: vtkResliceImageViewer provide slice change on scroll by default but vtkImageViewer2 doesn’t provide so we have to code callback, vtkResliceImageViewer also provide Oblique mode,Reslice mode(default) and  SliceChangeEvent that will be included in next blog.