[R-sig-Geo] Using the Z value for 3-D polygons?

[Jim Burke]

Hi Everyone,

QUESTION: How can I plot a spatial polygon (SpatialPolygonsDataFrame) as 
3-d? Perhaps using "spplot.polygons" with its z value?

GOAL: To have a series of polygons look like approximately like the last 
example in the PDF below.
http://ocw.mit.edu/NR/rdonlyres/Urban-Studies-and-Planning/11-521Spatial-Database-Management-and-Advanced-Geographic-Information-SystemsSpring2003/ACA80C9F-4089-403E-9669-50763381D08A/0/lect13c.pdf

EXAMPLE SUGGESTION: Use "spplot.pologons" with the venerable SourceForge 
NC fig21.R example and using its color coding values as the polygon $z 
value? Assuming lat and long are in the sp.
http://r-spatial.sourceforge.net/gallery/#fig21.R

Then if its not as straightforward as above, what would be the steps to 
convert a spatial polygon to points or something to graph that way?

Thanks,
Jim Burke