[vtkusers] How to add an axes to the render widow?

[An Jiye]

Hi.

I have created a pipeline vtkAxes->vtkPolyDataMapper->vtkActor in order to
display an axes with other actural actors. I think this will be convinent
for user to guess the position of other actors.

But I can only see this axes(three lines) when there is no other actors.
After I added some other vtkActor(some isosurfaces) to the renderer, I can
not see it. Finally I found that it is too small to see. So how can I
automatically scale it to fit the current actors?

Thank you in advance.

An Jiye