Using PlotPolysOnStaticMap function in RgoogleMaps: Plotting my polygons returns colors in "holes"

Question

As the title says I am trying to plot a polygons using the PlotPolysonStaticMap function in RgoogleMaps. My polygon is a subset from a larger dataset of World Wildlife Fund (WWF) ecoregions. Since the bounds of my ecoregion confine the bounds of another ecoregion there should be a "hole" or a blank space in the midst of my polygons. When I plot the shapefile using the plot function the hole appears as white. When I plot the polygon over the base map from RgoogleMaps the hole appears in color and I do not know how to change this.

The full map is available here. It needs to be downloaded and unzipped for my code to work.

library(rgdal)
library(RgoogleMaps)
library(PBSmapping)

WWF<-readOGR(dsn="wwf_terr_eco.shp",layer="wwf_terr_eco"
ACADIA<-WWF[WWF@data$ECO_NAME%in%c("New England-Acadian forests"),]
ACADIA <- SpatialPolygons(ACADIA@polygons,proj4string=ACADIA@proj4string)

add.alpha <- function(col, alpha=1){
if(missing(col))
stop("Please provide a vector of colours.")
apply(sapply(col, col2rgb)/255, 2, 
    function(x) 
      rgb(x[1], x[2], x[3], alpha=alpha))  
 }

mycol=add.alpha("#507415",alpha=.4)

terrMap<-GetMap(center=c(46,-66.8),zoom=6,maptype="terrain")
PlotOnStaticMap(terrMap) 
PlotPolysOnStaticMap(terrMap, ACADIA_ONLY,col =mycol ,border = NULL, lwd = 0.25,
                 verbose = T)

Thanks!

Answer 1

I do not know well RgoogleMaps package (the error seems come from the function PlotPolysOnStaticMap behavior with complex polygons), so I can't answer your question precisely, but I you with an other way you can play with OpenStreetMap.

library(rgdal)
library(OpenStreetMap)

WWF<-readOGR(dsn="/home/delaye/Téléchargements/official/",layer="wwf_terr_ecos")
ACADIA<-WWF[WWF@data$ECO_NAME%in%c("New England-Acadian forests"),]

##reprojection with osm system
ACADIA<-spTransform(ACADIA,osm())

##alpha definition
add.alpha <- function(col, alpha=1){
  if(missing(col))
    stop("Please provide a vector of colours.")
  apply(sapply(col, col2rgb)/255, 2, 
        function(x) 
          rgb(x[1], x[2], x[3], alpha=alpha))  
}
mycol=add.alpha("#507415",alpha=.4)

##load data from osm (you can play with type='bing' to)
map.osm<-openmap(c(49.849184,-75.214844),c(42.013233,-59.877930),type="osm")
plot(map.osm)
##add you datalayer on the plot
plot(ACADIA,add=T,col=mycol)

and the result is

I hope it can help