Learn how to integrate vtk with pyqt in python

This tutorial will show

• Integrate the VTK widget into a QT application
• Pass signals from QT to VTK
• Pass signals from VTK to QT

This tutorial starts with a visualization of volumetric data based on glyphs. The explanation for this part can be found here

The first task is encapsulating the logic into a class. This will make it easier to include into a larger program.

Now the class will be transformed into a Qt-Widget and embedded inside a very simple PyQt interface. We have not connected any of the controls yet. The important changes are

• Changing the windowInteractor to a QVTKRenderWindowInteractor
• Getting the render window from the interactor
• Moving the interactor.Initialize() call to the start method. This method must be called after the widget is visible.
• Encapsulate the QVTKRenderWindowInteractor into a QFrame, which can be manipulated with more freedom.

Notice that now the main loop is handled by PyQt instead of VTK.

This is very easy. It is only necessary to connect a Qt event to a method in the vtk class.

This is more tricky. The objective is to notify Qt after the user picks and object in the vtk widget. The default behaviour of vtk is to fire a pick event when the user presses the p key on the keypboard. This is not very intuitive, so first we need to translate standard clicks into picks. The complete chain is

1. Create pick events from click events. See the method click_to_pick.
2. Capture pick events and emit a QtSignal. See the method process_pick
3. Connect the new QtSignal to a method in the main application class.