MedicalDemo4
VTKExamples/Java/Medical/MedicalDemo4
Description¶
Volume rendering of the dataset.
Info
The example uses FullHead.mhd which references FullHead.raw.gz.
Note
This original source code for this example is here.
Code¶
MedicalDemo4.java
import vtk.vtkNamedColors; import vtk.vtkNativeLibrary; import vtk.vtkRenderWindow; import vtk.vtkRenderWindowInteractor; import vtk.vtkRenderer; import vtk.vtkMetaImageReader; import vtk.vtkCamera; import vtk.vtkColorTransferFunction; import vtk.vtkPiecewiseFunction; import vtk.vtkFixedPointVolumeRayCastMapper; import vtk.vtkVolumeProperty; import vtk.vtkVolume; public class MedicalDemo4 { // ----------------------------------------------------------------- // Load VTK library and print which library was not properly loaded static { if (!vtkNativeLibrary.LoadAllNativeLibraries()) { for (vtkNativeLibrary lib : vtkNativeLibrary.values()) { if (!lib.IsLoaded()) { System.out.println(lib.GetLibraryName() + " not loaded"); } } } vtkNativeLibrary.DisableOutputWindow(null); } // ----------------------------------------------------------------- public static void main(String args[]) { //parse command line arguments if (args.length != 1) { System.err.println("Usage: java -classpath ... Filename(.mhd) e.g FullHead.mhd"); return; } String inputFilename = args[0]; vtkNamedColors colors = new vtkNamedColors(); double Bgcolor[] = new double[4]; colors.GetColor("SteelBlue", Bgcolor); // Create the renderer, render window and interactor. vtkRenderer ren = new vtkRenderer(); vtkRenderWindow renWin = new vtkRenderWindow(); renWin.AddRenderer(ren); vtkRenderWindowInteractor iren = new vtkRenderWindowInteractor(); 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.) vtkMetaImageReader reader = new vtkMetaImageReader(); reader.SetFileName(inputFilename); // The volume will be displayed by ray-cast alpha compositing. // A ray-cast mapper is needed to do the ray-casting. vtkFixedPointVolumeRayCastMapper volumeMapper = new vtkFixedPointVolumeRayCastMapper(); volumeMapper.SetInputConnection(reader.GetOutputPort()); // 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). vtkColorTransferFunction volumeColor = new vtkColorTransferFunction(); volumeColor.AddRGBPoint(0, 0.0, 0.0, 0.0); volumeColor.AddRGBPoint(500, 1.0, 0.5, 0.3); volumeColor.AddRGBPoint(1000, 1.0, 0.5, 0.3); volumeColor.AddRGBPoint(1150, 1.0, 1.0, 0.9); // The opacity transfer function is used to control the opacity // of different tissue types. vtkPiecewiseFunction volumeScalarOpacity = new vtkPiecewiseFunction(); volumeScalarOpacity.AddPoint(0, 0.00); volumeScalarOpacity.AddPoint(500, 0.15); volumeScalarOpacity.AddPoint(1000, 0.15); volumeScalarOpacity.AddPoint(1150, 0.85); // 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. vtkPiecewiseFunction volumeGradientOpacity = new vtkPiecewiseFunction(); volumeGradientOpacity.AddPoint(0, 0.0); volumeGradientOpacity.AddPoint(90, 0.5); volumeGradientOpacity.AddPoint(100, 1.0); // 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. vtkVolumeProperty volumeProperty = new vtkVolumeProperty(); volumeProperty.SetColor(volumeColor); volumeProperty.SetScalarOpacity(volumeScalarOpacity); volumeProperty.SetGradientOpacity(volumeGradientOpacity); volumeProperty.SetInterpolationTypeToLinear(); volumeProperty.ShadeOn(); 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. vtkVolume volume = new vtkVolume(); volume.SetMapper(volumeMapper); volume.SetProperty(volumeProperty); double c[] = new double[3]; c=volume.GetCenter(); ren.AddViewProp(volume); // 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 = new vtkCamera(); 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); camera.Dolly(0.75); // Actors are added to the renderer. An initial camera view is created. // The Dolly() method moves the camera towards the FocalPoint, thereby enlarging the image. ren.SetActiveCamera(camera); // Set a background color for the renderer and set the size of the // render window (expressed in pixels). ren.SetBackground(Bgcolor); // Note that when camera movement occurs (as it does in the Dolly() // method), the clipping planes often need adjusting. Clipping planes // consist of two planes: near and far along the view direction. The // near plane clips out objects in front of the plane; the far plane // clips out objects behind the plane. This way only what is drawn // between the planes is actually rendered. ren.ResetCameraClippingRange (); renWin.SetSize(300, 300); renWin.Render(); iren.Initialize(); iren.Start(); } }