Displaying objects other than a volume in the renderer2d
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I am using the xtk toolkit. Is there a way to render objects other than 1 volume (with a labelmap) in the renderer2d. For example I have been able to add a sphere to the 3d renderer, but not the 2d?

I am trying to build in a simple region of interest function, which looks to an atlas to name the structures found in the ROI and reports them. For this I was thinking of loading the atlas structures as vtk objects and then looping through the points of the sphere and using the pick () object function. Do you think this approach will work? 
