PlotOnStaticMap function

overlays plot on background image of map tile

This function is the workhorse of the package RgoogleMaps. It overlays plot on background image of map tile

PlotOnStaticMap(MyMap, lat, lon, destfile, zoom = NULL, 
    size, GRAYSCALE = FALSE, add = FALSE, FUN = points, 
    mar = c(0, 0, 0, 0), NEWMAP = TRUE, TrueProj = TRUE, 
    axes = FALSE, atX = NULL, atY = NULL, verbose = 0, 
    ...)

Arguments

• MyMap: optional map object
• lat: latitude values to be overlaid
• lon: longitude values to be overlaid
• destfile: File to load the map image from or save to, depending on whether MyMap was passed.
• zoom: Google maps zoom level. optional if MyMap is passed, required if not.
• size: desired size of the map tile image. defaults to maximum size returned by the Gogle server, which is 640x640 pixels
• GRAYSCALE: Boolean toggle; if TRUE the colored map tile is rendered into a black & white image, see RGB2GRAY
• add: start a new plot or add to an existing
• FUN: plotting function to use for overlay; typical choices would be points and lines
• mar: outer margin in plot; if you want to see axes, change the default
• NEWMAP: load map from file or get it "new" from the static map server
• TrueProj: set to FALSE if you are willing to accept some degree of inaccuracy in the mapping. In that case, the coordinates of the image are in lat/lon and the user can simply overly points/lines/axis without worrying about projections
• axes: overlay axes ?
• atX: numeric; position of ticks on x-axis; if missing, axTicks is called for nice values; see axis
• atY: numeric; position of ticks on y-axis; if missing, axTicks is called for nice values; see axis
• verbose: level of verbosity
• ...: further arguments to be passed to FUN

Returns

the map object is returned via invisible(MyMap)

Author(s)

Markus Loecher

Examples

#The first step naturally will be to download a static map from the Google server. A simple example:

  if (0){
    lat = c(40.702147,40.711614,40.718217);
    lon = c(-74.015794,-74.012318,-73.998284);
    center = c(mean(lat), mean(lon));
    zoom <- min(MaxZoom(range(lat), range(lon)));
    #this overhead is taken care of implicitly by GetMap.bbox();              
    MyMap <- GetMap(center=center, zoom=zoom,markers = paste0("&markers=color:blue|label:S|",
             "40.702147,-74.015794&markers=color:green|label:G|40.711614,-74.012318&markers=",
             "color:red|color:red|label:C|40.718217,-73.998284"), destfile = "MyTile1.png");
                   
     tmp <- PlotOnStaticMap(MyMap, lat = lat, 
                            lon = lon, 
                            destfile = "MyTile1.png", cex=1.5,pch=20,
                            col=c('red', 'blue', 'green'), add=FALSE);
     #and add lines:
     PlotOnStaticMap(MyMap, lat = c(40.702147,40.711614,40.718217), 
                     lon = c(-74.015794,-74.012318,-73.998284), 
                     lwd=1.5,col=c('red', 'blue', 'green'), FUN = lines, add=TRUE)
        
  }