GetMap                  download a static map from the Google server
GetMap.bbox             download a static map from the Google server
LatLon2XY               computes the coordinate transformation from
                        lat/lon to map tile coordinates
LatLon2XY.centered      computes the centered coordinate transformation
                        from lat/lon to map tile coordinates
MapBackground           get static Map from the Google server
MaxZoom                 computes the maximum zoom level which will
                        contain the given lat/lon range
PlotOnStaticMap         overlays plot on background image of map tile
PlotPolysOnStaticMap    plots polygons on map
RGB2GRAY                translates an RGB image matrix to gray scale
RgoogleMaps-package     Utilities to enable overlays on Google Maps
SPGDF2matrix            image gridded spatial data, or convert to
                        format for image
Tile2R                  simple utility to offset and scale XY
                        coordinates with respect to the center
XY2LatLon               computes the centered coordinate transformation
                        from lat/lon to map tile coordinates
mypolygon               simple wrapper function to plot colored
                        polygons
qbbox                   computes bounding box
updateusr               Updates the 'usr' coordinates in the current
                        plot.
