ContourLines to SpatialPolygons

contoursToSP02.r

#create a slightly larger matrix and fill with relatively small values (60):
volcano2 <- matrix(60, nrow(volcano) + 2, ncol(volcano) + 2)

#copy the original matrix into the center of the new matrix:
volcano2[-nrow(volcano2),][,-ncol(volcano2)][-1,][,-1] <- volcano

#repeat the previous conversion steps and plot:
poly_volcano <- raster(volcano2)
poly_volcano <- rasterToContour(poly_volcano, levels = breaks)
poly_volcano <- SpatialLines2PolySet(poly_volcano)
poly_volcano <- PolySet2SpatialPolygons(poly_volcano)
png("volcano02.png", 200, 200)
par(oma = c(0,0,0,0), mar = c(0,0,0,0))
plot(poly_volcano, col = terrain.colors(length(poly_volcano)))
dev.off()