MedicalDemo4

vtk-examples/Cxx/Medical/MedicalDemo4

Description¶

Volume rendering of the dataset.

Usage

Note

This original source code for this example is here.

Info

The example uses src/Testing/Data/FullHead.mhd which references src/Testing/Data/FullHead.raw.gz.

Other languages

See (Python), (Java)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code¶

MedicalDemo4.cxx

// Derived from VTK/Examples/Cxx/Medical4.cxx
// This example reads a volume dataset and displays it via volume rendering.
//

#include <vtkCamera.h>
#include <vtkColorTransferFunction.h>
#include <vtkFixedPointVolumeRayCastMapper.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPiecewiseFunction.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkVolume.h>
#include <vtkVolumeProperty.h>

#include <array>

int main(int argc, char* argv[])
{
if (argc < 2)
{
cout << "Usage: " << argv[0] << "file.mhd e.g. FullHead.mhd" << endl;
return EXIT_FAILURE;
}

vtkNew<vtkNamedColors> colors;

std::array<unsigned char, 4> bkg{{51, 77, 102, 255}};
colors->SetColor("BkgColor", bkg.data());

// Create the renderer, the render window, and the interactor. The renderer
// draws into the render window, the interactor enables mouse- and
// keyboard-based interaction with the scene.
vtkNew<vtkRenderer> ren;
vtkNew<vtkRenderWindow> renWin;
vtkNew<vtkRenderWindowInteractor> iren;
iren->SetRenderWindow(renWin);

// The following reader is used to read a series of 2D slices (images)
// that compose the volume. The slice dimensions are set, and the
// pixel spacing. The data Endianness must also be specified. The reader
// uses the FilePrefix in combination with the slice number to construct
// filenames using the format FilePrefix.%d. (In this case the FilePrefix
// is the root name of the file: quarter.)

// The volume will be displayed by ray-cast alpha compositing.
// A ray-cast mapper is needed to do the ray-casting.
vtkNew<vtkFixedPointVolumeRayCastMapper> volumeMapper;

// The color transfer function maps voxel intensities to colors.
// It is modality-specific, and often anatomy-specific as well.
// The goal is to one color for flesh (between 500 and 1000)
// and another color for bone (1150 and over).
vtkNew<vtkColorTransferFunction> volumeColor;
volumeColor->AddRGBPoint(0, 0.0, 0.0, 0.0);
volumeColor->AddRGBPoint(500, 240.0 / 255.0, 184.0 / 255.0, 160.0 / 255.0);
volumeColor->AddRGBPoint(1000, 240.0 / 255.0, 184.0 / 255.0, 160.0 / 255.0);
volumeColor->AddRGBPoint(1150, 1.0, 1.0, 240.0 / 255.0); // Ivory

// The opacity transfer function is used to control the opacity
// of different tissue types.
vtkNew<vtkPiecewiseFunction> volumeScalarOpacity;

// The gradient opacity function is used to decrease the opacity
// in the "flat" regions of the volume while maintaining the opacity
// at the boundaries between tissue types. The gradient is measured
// as the amount by which the intensity changes over unit distance.
// For most medical data, the unit distance is 1mm.

// The VolumeProperty attaches the color and opacity functions to the
// volume, and sets other volume properties. The interpolation should
// be set to linear to do a high-quality rendering. The ShadeOn option
// turns on directional lighting, which will usually enhance the
// appearance of the volume and make it look more "3D". However,
// the quality of the shading depends on how accurately the gradient
// of the volume can be calculated, and for noisy data the gradient
// estimation will be very poor. The impact of the shading can be
// decreased by increasing the Ambient coefficient while decreasing
// the Diffuse and Specular coefficient. To increase the impact
// of shading, decrease the Ambient and increase the Diffuse and Specular.
vtkNew<vtkVolumeProperty> volumeProperty;
volumeProperty->SetColor(volumeColor);
volumeProperty->SetScalarOpacity(volumeScalarOpacity);
volumeProperty->SetInterpolationTypeToLinear();
volumeProperty->SetAmbient(0.4);
volumeProperty->SetDiffuse(0.6);
volumeProperty->SetSpecular(0.2);

// The vtkVolume is a vtkProp3D (like a vtkActor) and controls the position
// and orientation of the volume in world coordinates.
vtkNew<vtkVolume> volume;
volume->SetMapper(volumeMapper);
volume->SetProperty(volumeProperty);

// Finally, add the volume to the renderer

// Set up an initial view of the volume. The focal point will be the
// center of the volume, and the camera position will be 400mm to the
// patient's left (which is our right).
vtkCamera* camera = ren->GetActiveCamera();
double* c = volume->GetCenter();
camera->SetViewUp(0, 0, -1);
camera->SetPosition(c[0], c[1] - 400, c[2]);
camera->SetFocalPoint(c[0], c[1], c[2]);
camera->Azimuth(30.0);
camera->Elevation(30.0);

// Set a background color for the renderer
ren->SetBackground(colors->GetColor3d("BkgColor").GetData());

// Increase the size of the render window
renWin->SetSize(640, 480);
renWin->SetWindowName("MedicalDemo4");

// Interact with the data.
renWin->Render();
iren->Start();

return EXIT_SUCCESS;
}


CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(MedicalDemo4)

find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkIOImage
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2
vtkRenderingVolume
vtkRenderingVolumeOpenGL2
QUIET
)

if (NOT VTK_FOUND)
message("Skipping MedicalDemo4: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION:${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE}) add_executable(MedicalDemo4 MACOSX_BUNDLE MedicalDemo4.cxx ) target_link_libraries(MedicalDemo4 PRIVATE${VTK_LIBRARIES})
else ()
# include all components
add_executable(MedicalDemo4 MACOSX_BUNDLE MedicalDemo4.cxx )
target_link_libraries(MedicalDemo4 PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS MedicalDemo4 MODULES${VTK_LIBRARIES}
)
endif ()


cd MedicalDemo4/build


If VTK is installed:

cmake ..


If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..


Build the project:

make


and run it:

./MedicalDemo4


WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.