[vtkusers] QVTKWidget + volume misbehavior

[Dominik Szczerba]

I am doing something as trivial as:

	// record existing spacing
	image->GetSpacing(old_spacing);

	// modify it
	image->SetSpacing(new_spacing);
	image->Modified();

	// refresh display
	vtkWidget->GetRenderWindow()->Render();

	// debug
	image->GetSpacing(current_spacing);


which behaves correctly, with current_spacing = new_spacing and my 
outline actor responding to the changes.

The moment I call:

	ren1->AddVolume(volume); // volume is representation of image

I can properly see my volume only before calling Render(): 
current_spacing gets reset back to old_spacing right after.

1) Am I doing something obviously wrong (like I am not allowed to modify 
a registered volume)
2) What is caching the original image properties and why?

Thanks for any hints,
Dominik

-- 
Dominik Szczerba, PhD
Computational Physics Group
IT'IS Foundation for Research
http://www.itis.ethz.ch