.googleMapURL(latitude, longitude, position = NULL, zoom = 11, maptype = c("roadmap", "satellite", "terrain", "hybrid"), mark = FALSE, radius = 0)
.googleMapURL2(latitude, longitude, position = NULL, zoom = 12, width = 600, height = 400, maptype = c("roadmap", "satellite", "terrain", "hybrid"), mark = FALSE)
'roadmap'
, 'satellite'
, 'terrain'
, and 'hybrid'