Thanks for your answer. Today I was able to get it working with vtk 8.2 and Qt 5.15. I was able to display a renderer in a QML. However, it still does not work with vtk9. So something must be changed to work with vtk9 but I do not know what. Would you have a small piece of code that is able to do that: vtk9, Qt5.15, a renderer into QML?