[R-sig-Geo] 3D bars on a Geographic Map?

[Jim Burke]

I have a group of geographical polygons in lat long (epsg:4326) 
coordinates.
I would like to lay this polygon out at an angle.
I would like to put two 3D bar charts at the midpoint or close inside 
each polygon.

Can anyone provide an example of this? Or a web site with an example?

Thanks,
Jim Burke