Test.R

library(maptools)
library(plot3D)
ShapeFile <- readShapeSpatial('Test.shp')
Polygons <- slot(ShapeFile,"polygons")
coordinates <- list( Latitude  = numeric(0),
                     Longitude = numeric(0),
                     PolygonID = numeric(0) ) 
for(i in 1:length(Polygons)){
  Polygon <- Polygons[[i]]
  ID <- slot(Polygon, "ID")
  coords <- data.frame(slot(slot(Polygon,"Polygons")[[1]],"coords"))
  number.rows <- nrow(coords)
  coordinates$Longitude <- c(coordinates$Longitude, coords[,1])
  coordinates$Latitude  <- c(coordinates$Latitude , coords[,2])
  coordinates$PolygonID <- c(coordinates$PolygonID, rep(ID,number.rows))
}
coordinates <- as.data.frame(coordinates)
coordinates$z <- 0
polygon3D(coordinates$Longitude,coordinates$Latitude,coordinates$z,col="transparent")
for (i in 0:length(coordinates)){
    testpolygon <-  coordinates[coordinates$PolygonID == as.character(i),]    
    testpolygon$z <- 0 
    polygon3D(testpolygon$Longitude,
              testpolygon$Latitude,
              testpolygon$z,
              add=TRUE)
}