how to add an image to render window which had point cloud already

Support
3

I want to use the passed renderWindow as argument. my winodow is

  renderWindow = vtkSmartPointer<vtkGenericOpenGLRenderWindow>::New();
  renderWindow->AddRenderer(renderer_lidar);

when I try to add a image view,such as
renderWindow->AddRenderer(renderer_image);
than renderer_lidar is erased by renderer_image

If I addd an image(via vtkImageActor) to renderer_lidar, it is ok, adding to main window failed